2008-02-11 11:40:03 +00:00
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.\" Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
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.\" starting from a version by Davide Libenzi <davidel@xmailserver.org>
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.\"
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epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, ioprio_set.2, signalfd.2, spu_create.2, spu_run.2, timerfd_create.2, charmap.5, locale.5, nscd.conf.5, epoll.7, spufs.7, ldconfig.8, nscd.8: s/GPLv2+_3_PARA_SW/GPLv2+_SW_3_PARA/
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-03-10 09:29:45 +00:00
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.\" %%%LICENSE_START(GPLv2+_SW_3_PARA)
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2008-02-11 11:40:03 +00:00
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.\" This program is free software; you can redistribute it and/or modify
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.\" it under the terms of the GNU General Public License as published by
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.\" the Free Software Foundation; either version 2 of the License, or
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.\" (at your option) any later version.
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.\"
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.\" This program is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, ioprio_set.2, signalfd.2, spu_create.2, spu_run.2, timerfd_create.2, epoll.7, spufs.7: Global fix: Update info in source comments on where to get a copy of the GPL
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-03-10 09:28:52 +00:00
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, see
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.\" <http://www.gnu.org/licenses/>.
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epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, fallocate.2, futex.2, getcpu.2, getitimer.2, ioctl_list.2, ioprio_set.2, migrate_pages.2, move_pages.2, pciconfig_read.2, sendfile.2, setns.2, signalfd.2, spu_create.2, spu_run.2, sysinfo.2, timerfd_create.2, backtrace.3, cmsg.3, error.3, getpt.3, getrpcent.3, getrpcport.3, getsubopt.3, offsetof.3, program_invocation_name.3, rpc.3, rpmatch.3, rtnetlink.3, xdr.3, cciss.4, hpsa.4, pts.4, charmap.5, dir_colors.5, elf.5, gai.conf.5, locale.5, nscd.conf.5, nss.5, resolv.conf.5, rpc.5, arp.7, cpuset.7, ddp.7, epoll.7, fifo.7, futex.7, icmp.7, ip.7, ipv6.7, mailaddr.7, netdevice.7, packet.7, raw.7, regex.7, rtnetlink.7, socket.7, spufs.7, tcp.7, udp.7, unix.7, x25.7, ldconfig.8, nscd.8: Global fix: s/END_LICENSE/LICENSE_END/
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-03-12 09:26:07 +00:00
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.\" %%%LICENSE_END
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2008-02-11 11:40:03 +00:00
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.\"
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2008-10-10 14:42:19 +00:00
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.\" 2008-10-10, mtk: describe eventfd2(), and EFD_NONBLOCK and EFD_CLOEXEC
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.\"
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memusage.1, pldd.1, sprof.1, add_key.2, bind.2, bpf.2, clone.2, dup.2, epoll_ctl.2, eventfd.2, fanotify_init.2, fanotify_mark.2, futex.2, getdents.2, getpid.2, getrlimit.2, intro.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, keyctl.2, membarrier.2, memfd_create.2, mprotect.2, msgctl.2, msgop.2, nfsservctl.2, open.2, open_by_handle_at.2, openat2.2, outb.2, perf_event_open.2, pivot_root.2, recv.2, recvmmsg.2, request_key.2, sched_setaffinity.2, sched_setattr.2, seccomp.2, select.2, send.2, signalfd.2, spu_run.2, sysctl.2, timer_create.2, userfaultfd.2, wait.2, CPU_SET.3, abs.3, argz_add.3, backtrace.3, bsearch.3, bswap.3, clock_getcpuclockid.3, cmsg.3, dl_iterate_phdr.3, dlinfo.3, dlopen.3, drand48.3, drand48_r.3, duplocale.3, encrypt.3, endian.3, envz_add.3, errno.3, ffs.3, fopencookie.3, get_phys_pages.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrent_r.3, getgrouplist.3, getifaddrs.3, getline.3, getprotoent_r.3, getpwent_r.3, getpwnam.3, getservent_r.3, hsearch.3, insque.3, intro.3, lrint.3, lround.3, lseek64.3, mallinfo.3, malloc_hook.3, malloc_info.3, mbsinit.3, mbstowcs.3, mtrace.3, newlocale.3, ntp_gettime.3, offsetof.3, perror.3, posix_fallocate.3, posix_spawn.3, printf.3, psignal.3, pthread_attr_init.3, pthread_create.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_setaffinity_np.3, pthread_setname_np.3, pthread_sigmask.3, qsort.3, rand.3, random.3, rpc.3, rtnetlink.3, scalbln.3, shm_open.3, stdarg.3, strcat.3, strerror.3, strfmon.3, strptime.3, strsignal.3, strtod.3, strtok.3, strtol.3, strtoul.3, tsearch.3, wordexp.3, loop.4, vcs.4, veth.4, core.5, locale.5, slabinfo.5, cgroup_namespaces.7, cpuset.7, credentials.7, fanotify.7, feature_test_macros.7, inotify.7, ip.7, kernel_lockdown.7, man.7, mount_namespaces.7, namespaces.7, pid_namespaces.7, rtld-audit.7, sigevent.7, sock_diag.7, standards.7, unix.7, user_namespaces.7: tstamp
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2020-11-01 20:04:35 +00:00
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.TH EVENTFD 2 2020-11-01 Linux "Linux Programmer's Manual"
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2008-02-11 11:40:03 +00:00
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.SH NAME
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eventfd \- create a file descriptor for event notification
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.SH SYNOPSIS
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.B #include <sys/eventfd.h>
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_exit.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, close.2, connect.2, create_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, exit_group.2, fanotify_mark.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpid.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, getxattr.2, idle.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, ioctl.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_getfsmap.2, ioctl_tty.2, ioperm.2, iopl.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, mount.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, pause.2, pciconfig_read.2, perf_event_open.2, perfmonctl.2, personality.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, remap_file_pages.2, removexattr.2, rename.2, request_key.2, rmdir.2, rt_sigqueueinfo.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, set_mempolicy.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, setup.2, setxattr.2, sgetmask.2, shmctl.2, shmget.2, shutdown.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, stat.2, statfs.2, stime.2, swapon.2, symlink.2, sync.2, sysctl.2, sysinfo.2, syslog.2, time.2, timer_create.2, timer_delete.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, uname.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, ustat.2, utime.2, utimensat.2, vfork.2, vhangup.2, vm86.2, wait.2, wait4.2, write.2, CPU_SET.3, INFINITY.3, __ppc_get_timebase.3, __ppc_set_ppr_med.3, __ppc_yield.3, __setfpucw.3, a64l.3, abort.3, abs.3, acos.3, acosh.3, addseverity.3, adjtime.3, aio_cancel.3, aio_error.3, aio_fsync.3, aio_init.3, aio_read.3, aio_return.3, aio_suspend.3, aio_write.3, alloca.3, argz_add.3, asin.3, asinh.3, asprintf.3, assert.3, assert_perror.3, atan.3, atan2.3, atanh.3, atexit.3, atof.3, atoi.3, basename.3, bcmp.3, bcopy.3, bsd_signal.3, bsearch.3, bstring.3, btowc.3, byteorder.3, cabs.3, cacos.3, cacosh.3, canonicalize_file_name.3, carg.3, casin.3, casinh.3, catan.3, catanh.3, catopen.3, cbrt.3, ccos.3, ccosh.3, ceil.3, cexp.3, cexp2.3, cfree.3, cimag.3, clearenv.3, clock.3, clock_getcpuclockid.3, clog.3, clog10.3, clog2.3, closedir.3, cmsg.3, confstr.3, conj.3, copysign.3, cos.3, cosh.3, cpow.3, cproj.3, creal.3, crypt.3, csin.3, csinh.3, csqrt.3, ctan.3, ctanh.3, ctermid.3, ctime.3, daemon.3, difftime.3, dirfd.3, div.3, dlerror.3, dlopen.3, dlsym.3, drand48.3, drand48_r.3, duplocale.3, dysize.3, ecvt.3, ecvt_r.3, encrypt.3, endian.3, erf.3, erfc.3, err.3, errno.3, ether_aton.3, euidaccess.3, exec.3, exit.3, exp.3, exp10.3, exp2.3, expm1.3, fabs.3, fclose.3, fcloseall.3, fdim.3, fenv.3, ferror.3, fexecve.3, fflush.3, ffs.3, fgetc.3, fgetgrent.3, fgetpwent.3, fgetwc.3, fgetws.3, finite.3, flockfile.3, floor.3, fma.3, fmax.3, fmemopen.3, fmin.3, fmod.3, fmtmsg.3, fnmatch.3, fopen.3, fpathconf.3, fpclassify.3, fpurge.3, fputwc.3, fputws.3, fread.3, frexp.3, fseek.3, fseeko.3, ftime.3, ftok.3, fts.3, ftw.3, futimes.3, fwide.3, gamma.3, gcvt.3, get_nprocs_conf.3, get_phys_pages.3, getaddrinfo.3, getaddrinfo_a.3, getauxval.3, getcontext.3, getcwd.3, getdate.3, getdirentries.3, getdtablesize.3, getentropy.3, getenv.3, getfsent.3, getgrent.3, getgrent_r.3, getgrnam.3, getgrouplist.3, gethostbyname.3, gethostid.3, getifaddrs.3, getipnodebyname.3, getline.3, getloadavg.3, getlogin.3, getmntent.3, getnameinfo.3, getnetent.3, getnetent_r.3, getopt.3, getpass.3, getprotoent.3, getprotoent_r.3, getpt.3, getpw.3, getpwent.3, getpwent_r.3, getpwnam.3, getrpcent_r.3, getrpcport.3, gets.3, getservent.3, getservent_r.3, getspnam.3, getsubopt.3, getttyent.3, getumask.3, getusershell.3, getutent.3, getw.3, getwchar.3, glob.3, grantpt.3, group_member.3, gsignal.3, hsearch.3, hypot.3, iconv.3, iconv_close.3, iconv_open.3, if_nameindex.3, if_nametoindex.3, ilogb.3, index.3, inet.3, inet_net_pton.3, inet_ntop.3, infnan.3, initgroups.3, insque.3, isalpha.3, isatty.3, isfdtype.3, isgreater.3, iswalnum.3, iswalpha.3, iswblank.3, iswcntrl.3, iswctype.3, iswdigit.3, iswgraph.3, iswlower.3, iswprint.3, iswpunct.3, iswspace.3, iswupper.3, iswxdigit.3, j0.3, key_setsecret.3, killpg.3, ldexp.3, lgamma.3, localeconv.3, lockf.3, log.3, log10.3, log1p.3, log2.3, logb.3, login.3, lrint.3, lround.3, lsearch.3, lseek64.3, makecontext.3, malloc.3, malloc_get_state.3, malloc_hook.3, malloc_info.3, matherr.3, mblen.3, mbrlen.3, mbrtowc.3, mbsinit.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, mcheck.3, memccpy.3, memchr.3, memcmp.3, memcpy.3, memfrob.3, memmem.3, memmove.3, mempcpy.3, memset.3, mkdtemp.3, mkfifo.3, mkstemp.3, mktemp.3, modf.3, mpool.3, mq_close.3, mq_getattr.3, mq_notify.3, mq_open.3, mq_receive.3, mq_send.3, mq_unlink.3, mtrace.3, nan.3, netlink.3, newlocale.3, nextafter.3, nl_langinfo.3, offsetof.3, on_exit.3, open_memstream.3, opendir.3, openpty.3, perror.3, popen.3, posix_fallocate.3, posix_madvise.3, posix_memalign.3, posix_openpt.3, pow.3, pow10.3, printf.3, profil.3, psignal.3, pthread_atfork.3, pthread_attr_init.3, pthread_attr_setaffinity_np.3, pthread_attr_setdetachstate.3, pthread_attr_setguardsize.3, pthread_attr_setinheritsched.3, pthread_attr_setschedparam.3, pthread_attr_setschedpolicy.3, pthread_attr_setscope.3, pthread_attr_setstack.3, pthread_attr_setstackaddr.3, pthread_attr_setstacksize.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_cleanup_push_defer_np.3, pthread_create.3, pthread_detach.3, pthread_equal.3, pthread_exit.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_join.3, pthread_kill.3, pthread_rwlockattr_setkind_np.3, pthread_self.3, pthread_setaffinity_np.3, pthread_setcancelstate.3, pthread_setconcurrency.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_setschedprio.3, pthread_sigmask.3, pthread_sigqueue.3, pthread_testcancel.3, pthread_tryjoin_np.3, pthread_yield.3, ptsname.3, putenv.3, putgrent.3, putpwent.3, puts.3, putwchar.3, qecvt.3, qsort.3, raise.3, rand.3, random.3, random_r.3, rcmd.3, re_comp.3, readdir.3, realpath.3, remainder.3, remove.3, remquo.3, resolver.3, rewinddir.3, rexec.3, rint.3, round.3, rpmatch.3, rtime.3, rtnetlink.3, scalb.3, scalbln.3, scandir.3, scanf.3, sched_getcpu.3, seekdir.3, sem_close.3, sem_destroy.3, sem_getvalue.3, sem_init.3, sem_open.3, sem_post.3, sem_unlink.3, sem_wait.3, setaliasent.3, setbuf.3, setenv.3, setlocale.3, setlogmask.3, setnetgrent.3, shm_open.3, siginterrupt.3, signbit.3, significand.3, sigpause.3, sigqueue.3, sigset.3, sigvec.3, sigwait.3, sin.3, sincos.3, sinh.3, sleep.3, sockatmark.3, sqrt.3, statvfs.3, stdarg.3, stdio.3, stdio_ext.3, stpcpy.3, stpncpy.3, strcasecmp.3, strcat.3, strchr.3, strcmp.3, strcoll.3, strcpy.3, strdup.3, strerror.3, strfmon.3, strfromd.3, strfry.3, strftime.3, strlen.3, strnlen.3, strpbrk.3, strptime.3, strsep.3, strsignal.3, strspn.3, strstr.3, strtod.3, strtoimax.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, swab.3, sysconf.3, syslog.3, system.3, sysv_signal.3, tan.3, tanh.3, tcgetpgrp.3, tcgetsid.3, telldir.3, tempnam.3, termios.3, tgamma.3, timegm.3, timeradd.3, tmpfile.3, tmpnam.3, toascii.3, toupper.3, towctrans.3, towlower.3, towupper.3, trunc.3, tsearch.3, ttyname.3, ttyslot.3, tzset.3, ualarm.3, ulimit.3, ungetwc.3, unlocked_stdio.3, unlockpt.3, updwtmp.3, uselocale.3, usleep.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscasecmp.3, wcscat.3, wcschr.3, wcscmp.3, wcscpy.3, wcscspn.3, wcsdup.3, wcslen.3, wcsncasecmp.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcspbrk.3, wcsrchr.3, wcsrtombs.3, wcsspn.3, wcsstr.3, wcstoimax.3, wcstok.3, wcstombs.3, wcswidth.3, wctob.3, wctomb.3, wctrans.3, wctype.3, wcwidth.3, wmemchr.3, wmemcmp.3, wmemcpy.3, wmemmove.3, wmemset.3, wordexp.3, wprintf.3, xcrypt.3, y0.3, dsp56k.4, random.4, rtc.4, st.4, ddp.7, ip.7, ipv6.7, packet.7, rtnetlink.7, socket.7, tcp.7, udp.7, udplite.7, x25.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-15 15:16:29 +00:00
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.PP
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2008-02-11 11:40:03 +00:00
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.BI "int eventfd(unsigned int " initval ", int " flags );
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.SH DESCRIPTION
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.BR eventfd ()
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creates an "eventfd object" that can be used as
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eventfd.2, futex.2, mmap2.2, open.2, pciconfig_read.2, ptrace.2, reboot.2, request_key.2, sched_rr_get_interval.2, splice.2, stat.2, sync_file_range.2, syscalls.2, timer_create.2, vm86.2, pthread_attr_setscope.3, core.5, proc.5, aio.7, futex.7, netlink.7, time.7: Global fix: "userspace" ==> "user space" or "user-space"
Existing pages variously use "userspace or "user space".
But, "userspace" is not quite an English word.
So change "userspace" to "user space" or, when used
attributively, "user-space".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-10-21 06:04:42 +00:00
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an event wait/notify mechanism by user-space applications,
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and by the kernel to notify user-space applications of events.
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2008-02-11 11:40:03 +00:00
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The object contains an unsigned 64-bit integer
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.RI ( uint64_t )
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counter that is maintained by the kernel.
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This counter is initialized with the value specified in the argument
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.IR initval .
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_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
|
|
|
.PP
|
2018-12-01 08:30:07 +00:00
|
|
|
As its return value,
|
|
|
|
.BR eventfd ()
|
|
|
|
returns a new file descriptor that can be used to refer to the
|
|
|
|
eventfd object.
|
|
|
|
.PP
|
2010-08-30 05:15:21 +00:00
|
|
|
The following values may be bitwise ORed in
|
2008-10-10 14:34:15 +00:00
|
|
|
.IR flags
|
2014-06-16 20:25:04 +00:00
|
|
|
to change the behavior of
|
2008-10-10 14:34:15 +00:00
|
|
|
.BR eventfd ():
|
|
|
|
.TP
|
2010-08-30 05:15:21 +00:00
|
|
|
.BR EFD_CLOEXEC " (since Linux 2.6.27)"
|
2008-10-10 14:34:15 +00:00
|
|
|
Set the close-on-exec
|
|
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|
.RB ( FD_CLOEXEC )
|
|
|
|
flag on the new file descriptor.
|
2008-10-29 20:43:44 +00:00
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|
|
See the description of the
|
2008-10-10 14:34:15 +00:00
|
|
|
.B O_CLOEXEC
|
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|
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flag in
|
|
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|
.BR open (2)
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|
|
for reasons why this may be useful.
|
2010-08-30 04:39:47 +00:00
|
|
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.TP
|
2010-08-30 05:15:21 +00:00
|
|
|
.BR EFD_NONBLOCK " (since Linux 2.6.27)"
|
2010-08-30 04:39:47 +00:00
|
|
|
Set the
|
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|
|
.BR O_NONBLOCK
|
2018-12-01 08:42:01 +00:00
|
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|
file status flag on the open file description (see
|
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.BR open (2))
|
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referred to by the new file descriptor.
|
2010-08-30 04:39:47 +00:00
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|
|
Using this flag saves extra calls to
|
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|
|
.BR fcntl (2)
|
|
|
|
to achieve the same result.
|
2010-08-30 05:15:21 +00:00
|
|
|
.TP
|
|
|
|
.BR EFD_SEMAPHORE " (since Linux 2.6.30)"
|
|
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|
Provide semaphore-like semantics for reads from the new file descriptor.
|
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See below.
|
2008-10-10 14:34:15 +00:00
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|
.PP
|
|
|
|
In Linux up to version 2.6.26, the
|
2008-02-11 11:40:03 +00:00
|
|
|
.I flags
|
2008-10-10 14:34:15 +00:00
|
|
|
argument is unused, and must be specified as zero.
|
_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
|
|
|
.PP
|
2018-12-01 08:30:07 +00:00
|
|
|
The following operations can be performed on the file descriptor returned by
|
|
|
|
.BR eventfd ():
|
2008-02-11 11:40:03 +00:00
|
|
|
.TP
|
|
|
|
.BR read (2)
|
2010-08-30 05:15:21 +00:00
|
|
|
Each successful
|
|
|
|
.BR read (2)
|
|
|
|
returns an 8-byte integer.
|
|
|
|
A
|
|
|
|
.BR read (2)
|
access.2, delete_module.2, eventfd.2, fallocate.2, fcntl.2, getrandom.2, init_module.2, open.2, seccomp.2, timerfd_create.2, openpty.3, pthread_spin_lock.3, shm_open.3, tempnam.3, fifo.7, keyrings.7, pid_namespaces.7, sched.7, thread-keyring.7: wfix (will fail --> fail/fails)
Reported-by: Pedro Alves <palves@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-10-20 14:55:10 +00:00
|
|
|
fails with the error
|
2010-08-30 05:15:21 +00:00
|
|
|
.B EINVAL
|
|
|
|
if the size of the supplied buffer is less than 8 bytes.
|
|
|
|
.IP
|
|
|
|
The value returned by
|
|
|
|
.BR read (2)
|
2014-01-01 03:15:14 +00:00
|
|
|
is in host byte order\(emthat is,
|
|
|
|
the native byte order for integers on the host machine.
|
2010-08-30 05:15:21 +00:00
|
|
|
.IP
|
|
|
|
The semantics of
|
|
|
|
.BR read (2)
|
|
|
|
depend on whether the eventfd counter currently has a nonzero value
|
|
|
|
and whether the
|
|
|
|
.BR EFD_SEMAPHORE
|
|
|
|
flag was specified when creating the eventfd file descriptor:
|
|
|
|
.RS
|
|
|
|
.IP * 3
|
|
|
|
If
|
|
|
|
.BR EFD_SEMAPHORE
|
|
|
|
was not specified and the eventfd counter has a nonzero value, then a
|
2008-02-11 11:40:03 +00:00
|
|
|
.BR read (2)
|
|
|
|
returns 8 bytes containing that value,
|
|
|
|
and the counter's value is reset to zero.
|
2010-08-30 05:15:21 +00:00
|
|
|
.IP *
|
|
|
|
If
|
|
|
|
.BR EFD_SEMAPHORE
|
|
|
|
was specified and the eventfd counter has a nonzero value, then a
|
|
|
|
.BR read (2)
|
|
|
|
returns 8 bytes containing the value 1,
|
|
|
|
and the counter's value is decremented by 1.
|
|
|
|
.IP *
|
|
|
|
If the eventfd counter is zero at the time of the call to
|
2008-02-11 11:40:03 +00:00
|
|
|
.BR read (2),
|
2010-08-30 05:15:21 +00:00
|
|
|
then the call either blocks until the counter becomes nonzero
|
|
|
|
(at which time, the
|
|
|
|
.BR read (2)
|
|
|
|
proceeds as described above)
|
2008-02-11 11:40:03 +00:00
|
|
|
or fails with the error
|
|
|
|
.B EAGAIN
|
accept.2, connect.2, eventfd.2, flock.2, open.2, posix_fadvise.2, read.2, recv.2, sched_setscheduler.2, select_tut.2, send.2, signalfd.2, splice.2, timerfd_create.2, write.2, flockfile.3, mkfifo.3, mq_notify.3, mq_open.3, pthread_tryjoin_np.3, scanf.3, random.4, ddp.7, epoll.7, fifo.7, ip.7, pipe.7, socket.7, spufs.7: Global fix: s/non-blocking/nonblocking/
The tendency in English, as prescribed in style guides like
Chicago MoS, is towards removing hyphens after prefixes
like "non-" etc.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2010-01-16 16:43:10 +00:00
|
|
|
if the file descriptor has been made nonblocking.
|
2010-08-30 05:15:21 +00:00
|
|
|
.RE
|
2008-02-11 11:40:03 +00:00
|
|
|
.TP
|
|
|
|
.BR write (2)
|
|
|
|
A
|
|
|
|
.BR write (2)
|
|
|
|
call adds the 8-byte integer value supplied in its
|
|
|
|
buffer to the counter.
|
|
|
|
The maximum value that may be stored in the counter is the largest
|
|
|
|
unsigned 64-bit value minus 1 (i.e., 0xfffffffffffffffe).
|
|
|
|
If the addition would cause the counter's value to exceed
|
|
|
|
the maximum, then the
|
|
|
|
.BR write (2)
|
|
|
|
either blocks until a
|
|
|
|
.BR read (2)
|
|
|
|
is performed on the file descriptor,
|
|
|
|
or fails with the error
|
|
|
|
.B EAGAIN
|
accept.2, connect.2, eventfd.2, flock.2, open.2, posix_fadvise.2, read.2, recv.2, sched_setscheduler.2, select_tut.2, send.2, signalfd.2, splice.2, timerfd_create.2, write.2, flockfile.3, mkfifo.3, mq_notify.3, mq_open.3, pthread_tryjoin_np.3, scanf.3, random.4, ddp.7, epoll.7, fifo.7, ip.7, pipe.7, socket.7, spufs.7: Global fix: s/non-blocking/nonblocking/
The tendency in English, as prescribed in style guides like
Chicago MoS, is towards removing hyphens after prefixes
like "non-" etc.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2010-01-16 16:43:10 +00:00
|
|
|
if the file descriptor has been made nonblocking.
|
2008-02-11 11:40:03 +00:00
|
|
|
.IP
|
|
|
|
A
|
|
|
|
.BR write (2)
|
access.2, delete_module.2, eventfd.2, fallocate.2, fcntl.2, getrandom.2, init_module.2, open.2, seccomp.2, timerfd_create.2, openpty.3, pthread_spin_lock.3, shm_open.3, tempnam.3, fifo.7, keyrings.7, pid_namespaces.7, sched.7, thread-keyring.7: wfix (will fail --> fail/fails)
Reported-by: Pedro Alves <palves@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-10-20 14:55:10 +00:00
|
|
|
fails with the error
|
2008-02-11 11:40:03 +00:00
|
|
|
.B EINVAL
|
|
|
|
if the size of the supplied buffer is less than 8 bytes,
|
|
|
|
or if an attempt is made to write the value 0xffffffffffffffff.
|
|
|
|
.TP
|
|
|
|
.BR poll "(2), " select "(2) (and similar)"
|
|
|
|
The returned file descriptor supports
|
|
|
|
.BR poll (2)
|
|
|
|
(and analogously
|
|
|
|
.BR epoll (7))
|
|
|
|
and
|
|
|
|
.BR select (2),
|
|
|
|
as follows:
|
|
|
|
.RS
|
|
|
|
.IP * 3
|
|
|
|
The file descriptor is readable
|
|
|
|
(the
|
|
|
|
.BR select (2)
|
|
|
|
.I readfds
|
|
|
|
argument; the
|
|
|
|
.BR poll (2)
|
|
|
|
.B POLLIN
|
|
|
|
flag)
|
|
|
|
if the counter has a value greater than 0.
|
|
|
|
.IP *
|
|
|
|
The file descriptor is writable
|
|
|
|
(the
|
|
|
|
.BR select (2)
|
|
|
|
.I writefds
|
|
|
|
argument; the
|
|
|
|
.BR poll (2)
|
|
|
|
.B POLLOUT
|
|
|
|
flag)
|
|
|
|
if it is possible to write a value of at least "1" without blocking.
|
|
|
|
.IP *
|
2008-08-18 11:09:15 +00:00
|
|
|
If an overflow of the counter value was detected,
|
|
|
|
then
|
2008-02-11 11:40:03 +00:00
|
|
|
.BR select (2)
|
2008-08-18 11:09:15 +00:00
|
|
|
indicates the file descriptor as being both readable and writable, and
|
2008-02-11 11:40:03 +00:00
|
|
|
.BR poll (2)
|
2008-08-18 11:09:15 +00:00
|
|
|
returns a
|
2008-02-11 11:40:03 +00:00
|
|
|
.B POLLERR
|
2008-08-18 11:09:15 +00:00
|
|
|
event.
|
2008-02-11 11:40:03 +00:00
|
|
|
As noted above,
|
|
|
|
.BR write (2)
|
|
|
|
can never overflow the counter.
|
|
|
|
However an overflow can occur if 2^64
|
|
|
|
eventfd "signal posts" were performed by the KAIO
|
|
|
|
subsystem (theoretically possible, but practically unlikely).
|
|
|
|
If an overflow has occurred, then
|
|
|
|
.BR read (2)
|
|
|
|
will return that maximum
|
|
|
|
.I uint64_t
|
|
|
|
value (i.e., 0xffffffffffffffff).
|
|
|
|
.RE
|
|
|
|
.IP
|
|
|
|
The eventfd file descriptor also supports the other file-descriptor
|
|
|
|
multiplexing APIs:
|
2013-01-28 11:53:13 +00:00
|
|
|
.BR pselect (2)
|
2008-02-11 11:40:03 +00:00
|
|
|
and
|
2013-01-28 11:53:13 +00:00
|
|
|
.BR ppoll (2).
|
2008-02-11 11:40:03 +00:00
|
|
|
.TP
|
|
|
|
.BR close (2)
|
|
|
|
When the file descriptor is no longer required it should be closed.
|
|
|
|
When all file descriptors associated with the same eventfd object
|
|
|
|
have been closed, the resources for object are freed by the kernel.
|
|
|
|
.PP
|
|
|
|
A copy of the file descriptor created by
|
|
|
|
.BR eventfd ()
|
|
|
|
is inherited by the child produced by
|
|
|
|
.BR fork (2).
|
|
|
|
The duplicate file descriptor is associated with the same
|
|
|
|
eventfd object.
|
|
|
|
File descriptors created by
|
|
|
|
.BR eventfd ()
|
|
|
|
are preserved across
|
2010-08-29 05:34:37 +00:00
|
|
|
.BR execve (2),
|
|
|
|
unless the close-on-exec flag has been set.
|
getent.1, intro.1, time.1, _exit.2, _syscall.2, accept.2, access.2, acct.2, adjtimex.2, alarm.2, alloc_hugepages.2, arch_prctl.2, bdflush.2, bind.2, brk.2, cacheflush.2, capget.2, chdir.2, chmod.2, chown.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, exit_group.2, faccessat.2, fchmodat.2, fchownat.2, fcntl.2, flock.2, fork.2, fstatat.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_robust_list.2, get_thread_area.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpid.2, getpriority.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, getxattr.2, idle.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl.2, ioctl_list.2, ioperm.2, iopl.2, ioprio_set.2, ipc.2, kcmp.2, kill.2, killpg.2, link.2, linkat.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, migrate_pages.2, mincore.2, mkdir.2, mkdirat.2, mknod.2, mknodat.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, mount.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open.2, openat.2, outb.2, pause.2, pciconfig_read.2, perf_event_open.2, perfmonctl.2, personality.2, pipe.2, pivot_root.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readlink.2, readlinkat.2, readv.2, reboot.2, recv.2, remap_file_pages.2, removexattr.2, rename.2, renameat.2, rmdir.2, rt_sigqueueinfo.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, select.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, setup.2, setxattr.2, shmctl.2, shmget.2, shmop.2, shutdown.2, sigaction.2, sigaltstack.2, signal.2, signalfd.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, stat.2, statfs.2, stime.2, swapon.2, symlink.2, symlinkat.2, sync.2, sync_file_range.2, sysctl.2, sysfs.2, sysinfo.2, syslog.2, tee.2, time.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, uname.2, unimplemented.2, unlink.2, unlinkat.2, uselib.2, ustat.2, utime.2, utimensat.2, vfork.2, vhangup.2, vm86.2, vmsplice.2, wait.2, wait4.2, write.2, CPU_SET.3, INFINITY.3, MB_CUR_MAX.3, MB_LEN_MAX.3, __setfpucw.3, a64l.3, abort.3, abs.3, acos.3, acosh.3, addseverity.3, adjtime.3, aio_cancel.3, aio_error.3, aio_fsync.3, aio_read.3, aio_return.3, aio_suspend.3, aio_write.3, alloca.3, argz_add.3, asin.3, asinh.3, asprintf.3, assert.3, assert_perror.3, atan.3, atan2.3, atanh.3, atexit.3, atof.3, atoi.3, backtrace.3, basename.3, bcmp.3, bcopy.3, bindresvport.3, bsd_signal.3, bsearch.3, bstring.3, btowc.3, btree.3, byteorder.3, bzero.3, cabs.3, cacos.3, cacosh.3, canonicalize_file_name.3, carg.3, casin.3, casinh.3, catan.3, catanh.3, catgets.3, catopen.3, cbrt.3, ccos.3, ccosh.3, ceil.3, cerf.3, cexp.3, cexp2.3, cfree.3, cimag.3, clearenv.3, clock.3, clock_getcpuclockid.3, clog.3, clog10.3, clog2.3, closedir.3, cmsg.3, confstr.3, conj.3, copysign.3, cos.3, cosh.3, cpow.3, cproj.3, creal.3, crypt.3, csin.3, csinh.3, csqrt.3, ctan.3, ctanh.3, ctermid.3, ctime.3, daemon.3, dbopen.3, des_crypt.3, difftime.3, dirfd.3, div.3, dl_iterate_phdr.3, dlopen.3, dprintf.3, drand48.3, drand48_r.3, dysize.3, ecvt.3, ecvt_r.3, encrypt.3, end.3, endian.3, envz_add.3, erf.3, erfc.3, err.3, errno.3, error.3, ether_aton.3, euidaccess.3, exec.3, exit.3, exp.3, exp10.3, exp2.3, expm1.3, fabs.3, fclose.3, fcloseall.3, fdim.3, fenv.3, ferror.3, fexecve.3, fflush.3, ffs.3, fgetgrent.3, fgetpwent.3, fgetwc.3, fgetws.3, finite.3, flockfile.3, floor.3, fma.3, fmax.3, fmemopen.3, fmin.3, fmod.3, fmtmsg.3, fnmatch.3, fopen.3, fpathconf.3, fpclassify.3, fpurge.3, fputwc.3, fputws.3, fread.3, frexp.3, fseek.3, fseeko.3, ftime.3, ftok.3, fts.3, ftw.3, futimes.3, fwide.3, gamma.3, gcvt.3, getaddrinfo.3, getaddrinfo_a.3, getauxval.3, getcontext.3, getcwd.3, getdate.3, getdirentries.3, getdtablesize.3, getenv.3, getfsent.3, getgrent.3, getgrent_r.3, getgrnam.3, getgrouplist.3, gethostbyname.3, gethostid.3, getipnodebyname.3, getline.3, getloadavg.3, getlogin.3, getmntent.3, getnameinfo.3, getnetent.3, getnetent_r.3, getopt.3, getpass.3, getprotoent.3, getprotoent_r.3, getpt.3, getpw.3, getpwent.3, getpwent_r.3, getpwnam.3, getrpcent.3, getrpcent_r.3, getrpcport.3, gets.3, getservent.3, getservent_r.3, getspnam.3, getttyent.3, getumask.3, getusershell.3, getutent.3, getw.3, getwchar.3, glob.3, grantpt.3, gsignal.3, hash.3, hsearch.3, hypot.3, iconv.3, iconv_close.3, iconv_open.3, ilogb.3, index.3, inet.3, inet_ntop.3, inet_pton.3, infnan.3, initgroups.3, insque.3, intro.3, isalpha.3, isatty.3, isgreater.3, iswalnum.3, iswalpha.3, iswblank.3, iswcntrl.3, iswctype.3, iswdigit.3, iswgraph.3, iswlower.3, iswprint.3, iswpunct.3, iswspace.3, iswupper.3, iswxdigit.3, j0.3, key_setsecret.3, ldexp.3, lgamma.3, lio_listio.3, localeconv.3, lockf.3, log.3, log10.3, log1p.3, log2.3, logb.3, login.3, longjmp.3, lrint.3, lround.3, lsearch.3, lseek64.3, makecontext.3, makedev.3, malloc.3, malloc_hook.3, mblen.3, mbrlen.3, mbrtowc.3, mbsinit.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, memccpy.3, memchr.3, memcmp.3, memcpy.3, memfrob.3, memmem.3, memmove.3, mempcpy.3, memset.3, mkdtemp.3, mkfifo.3, mkfifoat.3, mkstemp.3, mktemp.3, modf.3, mpool.3, mq_close.3, mq_getattr.3, mq_notify.3, mq_open.3, mq_receive.3, mq_send.3, mq_unlink.3, mtrace.3, nan.3, netlink.3, nextafter.3, nl_langinfo.3, offsetof.3, on_exit.3, opendir.3, openpty.3, perror.3, popen.3, posix_fallocate.3, posix_memalign.3, posix_openpt.3, pow.3, pow10.3, printf.3, profil.3, program_invocation_name.3, psignal.3, pthread_kill_other_threads_np.3, ptsname.3, putenv.3, putgrent.3, putpwent.3, puts.3, putwchar.3, qecvt.3, qsort.3, queue.3, raise.3, rand.3, random.3, random_r.3, rcmd.3, re_comp.3, readdir.3, realpath.3, recno.3, regex.3, remainder.3, remove.3, remquo.3, resolver.3, rewinddir.3, rexec.3, rint.3, round.3, rpc.3, rpmatch.3, rtime.3, rtnetlink.3, scalb.3, scalbln.3, scandir.3, scandirat.3, scanf.3, seekdir.3, sem_close.3, sem_destroy.3, sem_getvalue.3, sem_init.3, sem_open.3, sem_post.3, sem_unlink.3, sem_wait.3, setaliasent.3, setbuf.3, setenv.3, setjmp.3, setlocale.3, setlogmask.3, setnetgrent.3, shm_open.3, siginterrupt.3, signbit.3, significand.3, sigpause.3, sigqueue.3, sigset.3, sigsetops.3, sigvec.3, sin.3, sincos.3, sinh.3, sleep.3, sockatmark.3, sqrt.3, statvfs.3, stdarg.3, stdin.3, stdio.3, stdio_ext.3, stpcpy.3, stpncpy.3, strcasecmp.3, strcat.3, strchr.3, strcmp.3, strcoll.3, strcpy.3, strdup.3, strerror.3, strfmon.3, strfry.3, strftime.3, string.3, strlen.3, strnlen.3, strpbrk.3, strptime.3, strsep.3, strsignal.3, strspn.3, strstr.3, strtod.3, strtoimax.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, swab.3, sysconf.3, syslog.3, system.3, sysv_signal.3, tan.3, tanh.3, tcgetpgrp.3, tcgetsid.3, telldir.3, tempnam.3, termios.3, tgamma.3, timegm.3, timeradd.3, tmpfile.3, tmpnam.3, toascii.3, toupper.3, towctrans.3, towlower.3, towupper.3, trunc.3, tsearch.3, ttyname.3, ttyslot.3, tzset.3, ualarm.3, ulimit.3, ungetwc.3, unlocked_stdio.3, unlockpt.3, updwtmp.3, usleep.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscasecmp.3, wcscat.3, wcschr.3, wcscmp.3, wcscpy.3, wcscspn.3, wcsdup.3, wcslen.3, wcsncasecmp.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcspbrk.3, wcsrchr.3, wcsrtombs.3, wcsspn.3, wcsstr.3, wcstoimax.3, wcstok.3, wcstombs.3, wcswidth.3, wctob.3, wctomb.3, wctrans.3, wctype.3, wcwidth.3, wmemchr.3, wmemcmp.3, wmemcpy.3, wmemmove.3, wmemset.3, wordexp.3, wprintf.3, xcrypt.3, xdr.3, y0.3, cciss.4, console.4, console_codes.4, console_ioctl.4, dsp56k.4, fd.4, full.4, hd.4, hpsa.4, initrd.4, intro.4, lp.4, mem.4, mouse.4, null.4, pts.4, ram.4, random.4, rtc.4, sk98lin.4, st.4, tty.4, ttyS.4, tty_ioctl.4, vcs.4, wavelan.4, acct.5, charmap.5, dir_colors.5, filesystems.5, ftpusers.5, group.5, host.conf.5, hosts.5, hosts.equiv.5, intro.5, issue.5, locale.5, motd.5, networks.5, nologin.5, nscd.conf.5, passwd.5, proc.5, protocols.5, resolv.conf.5, rpc.5, securetty.5, services.5, shells.5, termcap.5, ttytype.5, utmp.5, armscii-8.7, arp.7, ascii.7, bootparam.7, capabilities.7, charsets.7, complex.7, cp1251.7, credentials.7, ddp.7, environ.7, epoll.7, fifo.7, futex.7, glob.7, hier.7, icmp.7, inotify.7, intro.7, ip.7, ipv6.7, iso_8859-1.7, iso_8859-10.7, iso_8859-11.7, iso_8859-13.7, iso_8859-14.7, iso_8859-15.7, iso_8859-16.7, iso_8859-2.7, iso_8859-3.7, iso_8859-4.7, iso_8859-5.7, iso_8859-6.7, iso_8859-7.7, iso_8859-8.7, iso_8859-9.7, koi8-r.7, koi8-u.7, locale.7, mailaddr.7, man.7, mq_overview.7, netdevice.7, netlink.7, numa.7, packet.7, path_resolution.7, pipe.7, posixoptions.7, pthreads.7, pty.7, raw.7, regex.7, rtld-audit.7, rtnetlink.7, sem_overview.7, shm_overview.7, sigevent.7, signal.7, socket.7, standards.7, suffixes.7, svipc.7, tcp.7, termio.7, time.7, udp.7, udplite.7, unicode.7, unix.7, uri.7, utf-8.7, x25.7, nscd.8, sync.8, tzselect.8, zdump.8, zic.8: Global fix: remove unneeded double quotes in .SH headings
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-02-24 18:01:36 +00:00
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.SH RETURN VALUE
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2008-02-11 11:40:03 +00:00
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On success,
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.BR eventfd ()
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returns a new eventfd file descriptor.
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On error, \-1 is returned and
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.I errno
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is set to indicate the error.
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.SH ERRORS
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2008-04-18 15:52:17 +00:00
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.TP
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.B EINVAL
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2010-08-30 05:15:21 +00:00
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An unsupported value was specified in
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.IR flags .
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2008-02-11 11:40:03 +00:00
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.TP
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.B EMFILE
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accept.2, dup.2, eventfd.2, execve.2, fcntl.2, memfd_create.2, open.2, perf_event_open.2, pipe.2, signalfd.2, socket.2, socketpair.2, spu_create.2, timerfd_create.2, getgrent.3, getgrnam.3, getlogin.3, getpwent.3, getpwnam.3, mq_open.3, opendir.3, sem_open.3, shm_open.3, tmpfile.3: ERRORS: standardize text for EMFILE error
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-27 15:35:01 +00:00
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The per-process limit on the number of open file descriptors has been reached.
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2008-02-11 11:40:03 +00:00
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.TP
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.B ENFILE
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The system-wide limit on the total number of open files has been
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reached.
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.TP
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.B ENODEV
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.\" Note from Davide:
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.\" The ENODEV error is basically never going to happen if
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.\" the kernel boots correctly. That error happen only if during
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.\" the kernel initialization, some error occur in the anonymous
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.\" inode source initialization.
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Could not mount (internal) anonymous inode device.
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.TP
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.B ENOMEM
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There was insufficient memory to create a new
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eventfd file descriptor.
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.SH VERSIONS
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.BR eventfd ()
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is available on Linux since kernel 2.6.22.
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Working support is provided in glibc since version 2.8.
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.\" eventfd() is in glibc 2.7, but reportedly does not build
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2008-10-10 14:34:15 +00:00
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The
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.BR eventfd2 ()
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system call (see NOTES) is available on Linux since kernel 2.6.27.
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2009-01-27 05:05:56 +00:00
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Since version 2.9, the glibc
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.BR eventfd ()
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wrapper will employ the
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.BR eventfd2 ()
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system call, if it is supported by the kernel.
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2015-05-20 10:00:03 +00:00
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lb lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR eventfd ()
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T} Thread safety MT-Safe
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.TE
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_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
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.sp 1
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2008-02-11 11:40:03 +00:00
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.SH CONFORMING TO
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.BR eventfd ()
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2008-10-10 14:34:15 +00:00
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and
|
2008-10-10 14:47:53 +00:00
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.BR eventfd2 ()
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2008-10-10 14:34:15 +00:00
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are Linux-specific.
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2008-02-11 11:40:03 +00:00
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.SH NOTES
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Applications can use an eventfd file descriptor instead of a pipe (see
|
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.BR pipe (2))
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in all cases where a pipe is used simply to signal events.
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The kernel overhead of an eventfd file descriptor
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is much lower than that of a pipe,
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and only one file descriptor is
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required (versus the two required for a pipe).
|
_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
|
|
|
.PP
|
2008-02-11 11:40:03 +00:00
|
|
|
When used in the kernel, an eventfd
|
eventfd.2, futex.2, mmap2.2, open.2, pciconfig_read.2, ptrace.2, reboot.2, request_key.2, sched_rr_get_interval.2, splice.2, stat.2, sync_file_range.2, syscalls.2, timer_create.2, vm86.2, pthread_attr_setscope.3, core.5, proc.5, aio.7, futex.7, netlink.7, time.7: Global fix: "userspace" ==> "user space" or "user-space"
Existing pages variously use "userspace or "user space".
But, "userspace" is not quite an English word.
So change "userspace" to "user space" or, when used
attributively, "user-space".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-10-21 06:04:42 +00:00
|
|
|
file descriptor can provide a bridge from kernel to user space, allowing,
|
2008-02-11 11:40:03 +00:00
|
|
|
for example, functionalities like KAIO (kernel AIO)
|
|
|
|
.\" or eventually syslets/threadlets
|
|
|
|
to signal to a file descriptor that some operation is complete.
|
_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
|
|
|
.PP
|
2008-02-11 11:40:03 +00:00
|
|
|
A key point about an eventfd file descriptor is that it can be
|
|
|
|
monitored just like any other file descriptor using
|
|
|
|
.BR select (2),
|
|
|
|
.BR poll (2),
|
|
|
|
or
|
|
|
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.BR epoll (7).
|
|
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|
This means that an application can simultaneously monitor the
|
|
|
|
readiness of "traditional" files and the readiness of other
|
|
|
|
kernel mechanisms that support the eventfd interface.
|
|
|
|
(Without the
|
|
|
|
.BR eventfd ()
|
|
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|
interface, these mechanisms could not be multiplexed via
|
|
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|
.BR select (2),
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|
.BR poll (2),
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|
or
|
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.BR epoll (7).)
|
_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
|
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.PP
|
2016-03-08 18:17:28 +00:00
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|
The current value of an eventfd counter can be viewed
|
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|
|
via the entry for the corresponding file descriptor in the process's
|
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.IR /proc/[pid]/fdinfo
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directory.
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See
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.BR proc (5)
|
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|
for further details.
|
|
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|
.\"
|
_exit.2, access.2, brk.2, chmod.2, clone.2, epoll_wait.2, eventfd.2, fork.2, getgroups.2, gethostname.2, getpid.2, getpriority.2, killpg.2, mmap.2, poll.2, posix_fadvise.2, pread.2, ptrace.2, readv.2, sched_setaffinity.2, select.2, seteuid.2, setgid.2, setresuid.2, setreuid.2, setuid.2, sigaction.2, signalfd.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, stat.2, timer_create.2, uname.2, wait.2, wait4.2, mq_notify.3, mq_open.3, sigqueue.3, man-pages.7: Remove "ABI" from "C library/kernel ABI differences" subheadings
The "ABI" doesn't really convey anything significant in
the title. These subsections are about describing differences
between the kernel and (g)libc interfaces.
Reported-by: Andries E. Brouwer <Andries.Brouwer@cwi.nl>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-05-08 11:08:00 +00:00
|
|
|
.SS C library/kernel differences
|
2008-10-10 14:34:15 +00:00
|
|
|
There are two underlying Linux system calls:
|
|
|
|
.BR eventfd ()
|
|
|
|
and the more recent
|
|
|
|
.BR eventfd2 ().
|
|
|
|
The former system call does not implement a
|
|
|
|
.I flags
|
|
|
|
argument.
|
|
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|
The latter system call implements the
|
|
|
|
.I flags
|
|
|
|
values described above.
|
|
|
|
The glibc wrapper function will use
|
|
|
|
.BR eventfd2 ()
|
|
|
|
where it is available.
|
2008-02-11 11:40:03 +00:00
|
|
|
.SS Additional glibc features
|
|
|
|
The GNU C library defines an additional type,
|
|
|
|
and two functions that attempt to abstract some of the details of
|
|
|
|
reading and writing on an eventfd file descriptor:
|
2017-08-16 09:17:26 +00:00
|
|
|
.PP
|
2008-02-11 11:40:03 +00:00
|
|
|
.in +4n
|
2017-08-16 09:17:26 +00:00
|
|
|
.EX
|
2008-02-11 11:40:03 +00:00
|
|
|
typedef uint64_t eventfd_t;
|
|
|
|
|
2008-02-22 13:34:34 +00:00
|
|
|
int eventfd_read(int fd, eventfd_t *value);
|
|
|
|
int eventfd_write(int fd, eventfd_t value);
|
2017-08-16 09:17:26 +00:00
|
|
|
.EE
|
2008-02-11 11:40:03 +00:00
|
|
|
.in
|
_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
|
|
|
.PP
|
2008-02-11 11:40:03 +00:00
|
|
|
The functions perform the read and write operations on an
|
|
|
|
eventfd file descriptor,
|
|
|
|
returning 0 if the correct number of bytes was transferred,
|
|
|
|
or \-1 otherwise.
|
2020-05-21 08:00:37 +00:00
|
|
|
.SH EXAMPLES
|
2008-02-11 11:40:03 +00:00
|
|
|
The following program creates an eventfd file descriptor
|
|
|
|
and then forks to create a child process.
|
|
|
|
While the parent briefly sleeps,
|
|
|
|
the child writes each of the integers supplied in the program's
|
|
|
|
command-line arguments to the eventfd file descriptor.
|
|
|
|
When the parent has finished sleeping,
|
|
|
|
it reads from the eventfd file descriptor.
|
_syscall.2, bpf.2, cacheflush.2, capget.2, chdir.2, chmod.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, copy_file_range.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, execveat.2, fallocate.2, flock.2, fork.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_mempolicy.2, get_robust_list.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpriority.2, getrandom.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_fat.2, ioctl_ficlonerange.2, ioctl_fideduperange.2, ioctl_tty.2, ioctl_userfaultfd.2, ioperm.2, iopl.2, ioprio_set.2, kcmp.2, kexec_load.2, keyctl.2, kill.2, link.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, mbind.2, membarrier.2, memfd_create.2, migrate_pages.2, mincore.2, mkdir.2, mknod.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open_by_handle_at.2, outb.2, perf_event_open.2, perfmonctl.2, personality.2, pivot_root.2, pkey_alloc.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readv.2, reboot.2, recv.2, recvmmsg.2, remap_file_pages.2, rename.2, request_key.2, restart_syscall.2, rt_sigqueueinfo.2, s390_pci_mmio_write.2, s390_runtime_instr.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setattr.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, seccomp.2, select.2, select_tut.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, sendmmsg.2, set_mempolicy.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setns.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, sgetmask.2, shmctl.2, shmget.2, shmop.2, sigaction.2, sigaltstack.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, spu_create.2, spu_run.2, stat.2, statfs.2, statx.2, subpage_prot.2, swapon.2, symlink.2, sync.2, sync_file_range.2, syscalls.2, sysctl.2, sysinfo.2, syslog.2, tee.2, time.2, timer_create.2, timer_getoverrun.2, timer_settime.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, unimplemented.2, unlink.2, unshare.2, uselib.2, userfaultfd.2, utime.2, utimensat.2, vfork.2, vmsplice.2, wait.2, wait4.2, write.2: Formatting fix: replace blank lines with .PP/.IP
Blank lines shouldn't generally appear in *roff source (other
than in code examples), since they create large vertical
spaces between text blocks.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 07:30:51 +00:00
|
|
|
.PP
|
2008-02-11 11:40:03 +00:00
|
|
|
The following shell session shows a sample run of the program:
|
2017-08-16 09:17:26 +00:00
|
|
|
.PP
|
2008-02-11 11:40:03 +00:00
|
|
|
.in +4n
|
2017-08-16 09:17:26 +00:00
|
|
|
.EX
|
eventfd.2, execve.2, getdents.2, ioprio_set.2, mprotect.2, signalfd.2, timerfd_create.2, wait.2, backtrace.3, clock_getcpuclockid.3, end.3, fmemopen.3, fopencookie.3, frexp.3, getdate.3, getgrouplist.3, getprotoent_r.3, getservent_r.3, gnu_get_libc_version.3, inet.3, inet_pton.3, makecontext.3, malloc.3, matherr.3, offsetof.3, pthread_attr_init.3, pthread_create.3, pthread_getattr_np.3, sem_wait.3, strftime.3, strtok.3, strtol.3, core.5, proc.5, cpuset.7, mq_overview.7: Global fix: Format user input in shell sessions in boldface
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2008-10-28 15:37:22 +00:00
|
|
|
.RB "$" " ./a.out 1 2 4 7 14"
|
2008-02-11 11:40:03 +00:00
|
|
|
Child writing 1 to efd
|
|
|
|
Child writing 2 to efd
|
|
|
|
Child writing 4 to efd
|
|
|
|
Child writing 7 to efd
|
|
|
|
Child writing 14 to efd
|
|
|
|
Child completed write loop
|
|
|
|
Parent about to read
|
|
|
|
Parent read 28 (0x1c) from efd
|
2017-08-16 09:17:26 +00:00
|
|
|
.EE
|
2008-11-04 14:03:49 +00:00
|
|
|
.in
|
eventfd.2, getdents.2, mprotect.2, signalfd.2, timerfd_create.2, wait.2, backtrace.3, clock_getcpuclockid.3, end.3, fmemopen.3, fopencookie.3, getdate.3, getgrouplist.3, getprotoent_r.3, getservent_r.3, gnu_get_libc_version.3, inet.3, inet_pton.3, makecontext.3, matherr.3, offsetof.3, pthread_attr_init.3, pthread_create.3, pthread_getattr_np.3, sem_wait.3, strtol.3, core.5: global fix: Add ".SS Program source" to EXAMPLE
Add ".SS Program source" to clearly distinguish shell session and
descriptive text from actual program code.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2008-10-28 15:51:05 +00:00
|
|
|
.SS Program source
|
eventfd.2, getdents.2, mprotect.2, signalfd.2, timerfd_create.2, wait.2, backtrace.3, clock_getcpuclockid.3, end.3, fmemopen.3, fopencookie.3, frexp.3, getaddrinfo.3, getdate.3, getgrouplist.3, getprotoent_r.3, getservent_r.3, gnu_get_libc_version.3, inet.3, inet_pton.3, makecontext.3, matherr.3, offsetof.3, pthread_attr_init.3, pthread_create.3, pthread_getattr_np.3, sem_wait.3, strftime.3, strtok.3, strtol.3, core.5: srcfix
s/\.R " "/\\\&/ as a way of getting a blank line after a .SS heading.
(Suggested by Sam Varshavchik <mrsam@courier-mta.com>)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2008-11-05 01:42:45 +00:00
|
|
|
\&
|
memusage.1, clone.2, eventfd.2, futex.2, getdents.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, keyctl.2, mmap.2, mprotect.2, msgop.2, recvmmsg.2, request_key.2, sched_setaffinity.2, seccomp.2, setns.2, tee.2, timer_create.2, timerfd_create.2, unshare.2, userfaultfd.2, wait.2, __ppc_get_timebase.3, backtrace.3, bswap.3, clock_getcpuclockid.3, dl_iterate_phdr.3, dlinfo.3, dlopen.3, duplocale.3, end.3, endian.3, fmemopen.3, fopencookie.3, frexp.3, ftw.3, getdate.3, getgrouplist.3, getifaddrs.3, getprotoent_r.3, getservent_r.3, gnu_get_libc_version.3, if_nameindex.3, inet.3, inet_net_pton.3, inet_pton.3, insque.3, makecontext.3, mallinfo.3, malloc_info.3, mallopt.3, matherr.3, mbstowcs.3, mcheck.3, mq_getattr.3, mq_notify.3, newlocale.3, offsetof.3, posix_spawn.3, pthread_attr_init.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_create.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_sigmask.3, scandir.3, sem_wait.3, strcat.3, strftime.3, strtok.3, strtol.3, strverscmp.3, loop.4, core.5, aio.7, fanotify.7, feature_test_macros.7, inotify.7, pkeys.7, unix.7, user_namespaces.7: Use .EX/.EE for EXAMPLE programs
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 08:44:33 +00:00
|
|
|
.EX
|
2008-02-11 11:40:03 +00:00
|
|
|
#include <sys/eventfd.h>
|
|
|
|
#include <unistd.h>
|
2020-09-10 21:13:25 +00:00
|
|
|
#include <inttypes.h> /* Definition of PRIu64 & PRIx64 */
|
2008-02-11 11:40:03 +00:00
|
|
|
#include <stdlib.h>
|
|
|
|
#include <stdio.h>
|
|
|
|
#include <stdint.h> /* Definition of uint64_t */
|
|
|
|
|
locale.1, memusage.1, pldd.1, _syscall.2, add_key.2, bind.2, bpf.2, chown.2, clone.2, copy_file_range.2, eventfd.2, execve.2, futex.2, getdents.2, getrlimit.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, kexec_load.2, keyctl.2, listxattr.2, lseek.2, membarrier.2, memfd_create.2, mmap.2, mprotect.2, msgop.2, open_by_handle_at.2, perf_event_open.2, pipe.2, readdir.2, readlink.2, readv.2, recvmmsg.2, request_key.2, sched_setaffinity.2, seccomp.2, select.2, select_tut.2, sendmmsg.2, setns.2, signalfd.2, spu_run.2, stat.2, sysctl.2, tee.2, timer_create.2, timerfd_create.2, truncate.2, uname.2, unshare.2, userfaultfd.2, ustat.2, wait.2, CPU_SET.3, __ppc_get_timebase.3, argz_add.3, asprintf.3, backtrace.3, basename.3, bswap.3, bzero.3, cacos.3, cacosh.3, catan.3, catanh.3, catgets.3, clock_getcpuclockid.3, confstr.3, ctime.3, dl_iterate_phdr.3, dlinfo.3, duplocale.3, encrypt.3, end.3, endian.3, fgetws.3, fmemopen.3, fopencookie.3, fputws.3, frexp.3, ftw.3, get_nprocs_conf.3, get_phys_pages.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrouplist.3, getifaddrs.3, getline.3, getlogin.3, getopt.3, getpass.3, getprotoent_r.3, getpwnam.3, getservent_r.3, getsubopt.3, glob.3, gnu_get_libc_version.3, hsearch.3, if_nameindex.3, index.3, inet.3, inet_net_pton.3, inet_pton.3, insque.3, iswblank.3, iswspace.3, makecontext.3, mallinfo.3, malloc_hook.3, malloc_info.3, mallopt.3, matherr.3, mbrtowc.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, mcheck.3, memchr.3, mq_getattr.3, mq_notify.3, newlocale.3, nl_langinfo.3, offsetof.3, perror.3, posix_spawn.3, printf.3, pthread_attr_init.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_create.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_mutexattr_setrobust.3, pthread_setaffinity_np.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_sigmask.3, qsort.3, rand.3, readdir.3, regex.3, rpmatch.3, rtime.3, scanf.3, sem_wait.3, setaliasent.3, setbuf.3, stpcpy.3, stpncpy.3, strcat.3, strchr.3, strcpy.3, strdup.3, strerror.3, strfromd.3, strftime.3, strlen.3, strnlen.3, strsep.3, strstr.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, termios.3, tsearch.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscat.3, wcscpy.3, wcslen.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcsrtombs.3, wcsstr.3, wcstok.3, wcstombs.3, wcwidth.3, wprintf.3, console_codes.4, dsp56k.4, full.4, initrd.4, loop.4, vcs.4, charmap.5, core.5, elf.5, locale.5, proc.5, repertoiremap.5, sysfs.5, termcap.5, aio.7, bpf-helpers.7, cgroups.7, charsets.7, complex.7, fanotify.7, feature_test_macros.7, inotify.7, locale.7, man-pages.7, man.7, pkeys.7, pthreads.7, rtld-audit.7, sock_diag.7, unix.7, user_namespaces.7, utf-8.7: Use '\e' rather than '\\' to get a backslash
Quoting Branden:
*roff escape sequences may sometimes look like C escapes, but that
is misleading. *roff is in part a macro language and that means
recursive expansion to arbitrary depths.
You can get away with "\\" in a context where no macro expansion
is taking place, but try to spell a literal backslash this way in
the argument to a macro and you will likely be unhappy with
results.
Try viewing the attached file with "man -l".
"\e" is the preferred and portable way to get a portable "escape
literal" going back to CSTR #54, the original Bell Labs troff
paper.
groff(7) discusses the issue:
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode. For a
printable backslash, use \e, or even better \[rs], to be
independent from the current escape character.
As of groff 1.22.4, groff_man(7) does as well:
\e Widely used in man pages to represent a backslash output
glyph. It works reliably as long as the .ec request is
not used, which should never happen in man pages, and it
is slightly more portable than the more exact ‘\(rs’
(“reverse solidus”) escape sequence.
People not concerned with portability to extremely old troffs should
probably just use \(rs (or \[rs]), as it means "the backslash
glyph", not "the glyph corresponding to whatever the current escape
character is".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2019-02-27 11:57:17 +00:00
|
|
|
#define handle_error(msg) \e
|
2008-02-11 11:40:03 +00:00
|
|
|
do { perror(msg); exit(EXIT_FAILURE); } while (0)
|
|
|
|
|
|
|
|
int
|
|
|
|
main(int argc, char *argv[])
|
|
|
|
{
|
sprof.1, eventfd.2, execve.2, futex.2, getdents.2, mprotect.2, open_by_handle_at.2, recvmmsg.2, sched_setaffinity.2, CPU_SET.3, backtrace.3, bsearch.3, dl_iterate_phdr.3, dlinfo.3, duplocale.3, encrypt.3, envz_add.3, fopencookie.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrent_r.3, getgrouplist.3, getifaddrs.3, getprotoent_r.3, getservent_r.3, hsearch.3, mallinfo.3, malloc_info.3, mbstowcs.3, mtrace.3, pthread_create.3, pthread_getcpuclockid.3, pthread_setaffinity_np.3, qsort.3, rand.3, strcat.3, strtok.3, tsearch.3, wordexp.3, core.5, aio.7, inotify.7, sock_diag.7, unix.7, user_namespaces.7: Use C99 style to declare loop counter variables
Rather than:
sometype x;
for (x = ....; ...)
use
for (sometype x = ...; ...)
This brings the declaration and use closer together (thus aiding
readability) and also clearly indicates the scope of the loop
counter variable.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2020-09-05 15:18:10 +00:00
|
|
|
int efd;
|
2008-02-11 11:40:03 +00:00
|
|
|
uint64_t u;
|
|
|
|
ssize_t s;
|
|
|
|
|
|
|
|
if (argc < 2) {
|
locale.1, memusage.1, pldd.1, _syscall.2, add_key.2, bind.2, bpf.2, chown.2, clone.2, copy_file_range.2, eventfd.2, execve.2, futex.2, getdents.2, getrlimit.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, kexec_load.2, keyctl.2, listxattr.2, lseek.2, membarrier.2, memfd_create.2, mmap.2, mprotect.2, msgop.2, open_by_handle_at.2, perf_event_open.2, pipe.2, readdir.2, readlink.2, readv.2, recvmmsg.2, request_key.2, sched_setaffinity.2, seccomp.2, select.2, select_tut.2, sendmmsg.2, setns.2, signalfd.2, spu_run.2, stat.2, sysctl.2, tee.2, timer_create.2, timerfd_create.2, truncate.2, uname.2, unshare.2, userfaultfd.2, ustat.2, wait.2, CPU_SET.3, __ppc_get_timebase.3, argz_add.3, asprintf.3, backtrace.3, basename.3, bswap.3, bzero.3, cacos.3, cacosh.3, catan.3, catanh.3, catgets.3, clock_getcpuclockid.3, confstr.3, ctime.3, dl_iterate_phdr.3, dlinfo.3, duplocale.3, encrypt.3, end.3, endian.3, fgetws.3, fmemopen.3, fopencookie.3, fputws.3, frexp.3, ftw.3, get_nprocs_conf.3, get_phys_pages.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrouplist.3, getifaddrs.3, getline.3, getlogin.3, getopt.3, getpass.3, getprotoent_r.3, getpwnam.3, getservent_r.3, getsubopt.3, glob.3, gnu_get_libc_version.3, hsearch.3, if_nameindex.3, index.3, inet.3, inet_net_pton.3, inet_pton.3, insque.3, iswblank.3, iswspace.3, makecontext.3, mallinfo.3, malloc_hook.3, malloc_info.3, mallopt.3, matherr.3, mbrtowc.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, mcheck.3, memchr.3, mq_getattr.3, mq_notify.3, newlocale.3, nl_langinfo.3, offsetof.3, perror.3, posix_spawn.3, printf.3, pthread_attr_init.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_create.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_mutexattr_setrobust.3, pthread_setaffinity_np.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_sigmask.3, qsort.3, rand.3, readdir.3, regex.3, rpmatch.3, rtime.3, scanf.3, sem_wait.3, setaliasent.3, setbuf.3, stpcpy.3, stpncpy.3, strcat.3, strchr.3, strcpy.3, strdup.3, strerror.3, strfromd.3, strftime.3, strlen.3, strnlen.3, strsep.3, strstr.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, termios.3, tsearch.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscat.3, wcscpy.3, wcslen.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcsrtombs.3, wcsstr.3, wcstok.3, wcstombs.3, wcwidth.3, wprintf.3, console_codes.4, dsp56k.4, full.4, initrd.4, loop.4, vcs.4, charmap.5, core.5, elf.5, locale.5, proc.5, repertoiremap.5, sysfs.5, termcap.5, aio.7, bpf-helpers.7, cgroups.7, charsets.7, complex.7, fanotify.7, feature_test_macros.7, inotify.7, locale.7, man-pages.7, man.7, pkeys.7, pthreads.7, rtld-audit.7, sock_diag.7, unix.7, user_namespaces.7, utf-8.7: Use '\e' rather than '\\' to get a backslash
Quoting Branden:
*roff escape sequences may sometimes look like C escapes, but that
is misleading. *roff is in part a macro language and that means
recursive expansion to arbitrary depths.
You can get away with "\\" in a context where no macro expansion
is taking place, but try to spell a literal backslash this way in
the argument to a macro and you will likely be unhappy with
results.
Try viewing the attached file with "man -l".
"\e" is the preferred and portable way to get a portable "escape
literal" going back to CSTR #54, the original Bell Labs troff
paper.
groff(7) discusses the issue:
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode. For a
printable backslash, use \e, or even better \[rs], to be
independent from the current escape character.
As of groff 1.22.4, groff_man(7) does as well:
\e Widely used in man pages to represent a backslash output
glyph. It works reliably as long as the .ec request is
not used, which should never happen in man pages, and it
is slightly more portable than the more exact ‘\(rs’
(“reverse solidus”) escape sequence.
People not concerned with portability to extremely old troffs should
probably just use \(rs (or \[rs]), as it means "the backslash
glyph", not "the glyph corresponding to whatever the current escape
character is".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2019-02-27 11:57:17 +00:00
|
|
|
fprintf(stderr, "Usage: %s <num>...\en", argv[0]);
|
2008-02-11 11:40:03 +00:00
|
|
|
exit(EXIT_FAILURE);
|
|
|
|
}
|
|
|
|
|
|
|
|
efd = eventfd(0, 0);
|
|
|
|
if (efd == \-1)
|
|
|
|
handle_error("eventfd");
|
|
|
|
|
|
|
|
switch (fork()) {
|
|
|
|
case 0:
|
sprof.1, eventfd.2, execve.2, futex.2, getdents.2, mprotect.2, open_by_handle_at.2, recvmmsg.2, sched_setaffinity.2, CPU_SET.3, backtrace.3, bsearch.3, dl_iterate_phdr.3, dlinfo.3, duplocale.3, encrypt.3, envz_add.3, fopencookie.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrent_r.3, getgrouplist.3, getifaddrs.3, getprotoent_r.3, getservent_r.3, hsearch.3, mallinfo.3, malloc_info.3, mbstowcs.3, mtrace.3, pthread_create.3, pthread_getcpuclockid.3, pthread_setaffinity_np.3, qsort.3, rand.3, strcat.3, strtok.3, tsearch.3, wordexp.3, core.5, aio.7, inotify.7, sock_diag.7, unix.7, user_namespaces.7: Use C99 style to declare loop counter variables
Rather than:
sometype x;
for (x = ....; ...)
use
for (sometype x = ...; ...)
This brings the declaration and use closer together (thus aiding
readability) and also clearly indicates the scope of the loop
counter variable.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2020-09-05 15:18:10 +00:00
|
|
|
for (int j = 1; j < argc; j++) {
|
locale.1, memusage.1, pldd.1, _syscall.2, add_key.2, bind.2, bpf.2, chown.2, clone.2, copy_file_range.2, eventfd.2, execve.2, futex.2, getdents.2, getrlimit.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, kexec_load.2, keyctl.2, listxattr.2, lseek.2, membarrier.2, memfd_create.2, mmap.2, mprotect.2, msgop.2, open_by_handle_at.2, perf_event_open.2, pipe.2, readdir.2, readlink.2, readv.2, recvmmsg.2, request_key.2, sched_setaffinity.2, seccomp.2, select.2, select_tut.2, sendmmsg.2, setns.2, signalfd.2, spu_run.2, stat.2, sysctl.2, tee.2, timer_create.2, timerfd_create.2, truncate.2, uname.2, unshare.2, userfaultfd.2, ustat.2, wait.2, CPU_SET.3, __ppc_get_timebase.3, argz_add.3, asprintf.3, backtrace.3, basename.3, bswap.3, bzero.3, cacos.3, cacosh.3, catan.3, catanh.3, catgets.3, clock_getcpuclockid.3, confstr.3, ctime.3, dl_iterate_phdr.3, dlinfo.3, duplocale.3, encrypt.3, end.3, endian.3, fgetws.3, fmemopen.3, fopencookie.3, fputws.3, frexp.3, ftw.3, get_nprocs_conf.3, get_phys_pages.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrouplist.3, getifaddrs.3, getline.3, getlogin.3, getopt.3, getpass.3, getprotoent_r.3, getpwnam.3, getservent_r.3, getsubopt.3, glob.3, gnu_get_libc_version.3, hsearch.3, if_nameindex.3, index.3, inet.3, inet_net_pton.3, inet_pton.3, insque.3, iswblank.3, iswspace.3, makecontext.3, mallinfo.3, malloc_hook.3, malloc_info.3, mallopt.3, matherr.3, mbrtowc.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, mcheck.3, memchr.3, mq_getattr.3, mq_notify.3, newlocale.3, nl_langinfo.3, offsetof.3, perror.3, posix_spawn.3, printf.3, pthread_attr_init.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_create.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_mutexattr_setrobust.3, pthread_setaffinity_np.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_sigmask.3, qsort.3, rand.3, readdir.3, regex.3, rpmatch.3, rtime.3, scanf.3, sem_wait.3, setaliasent.3, setbuf.3, stpcpy.3, stpncpy.3, strcat.3, strchr.3, strcpy.3, strdup.3, strerror.3, strfromd.3, strftime.3, strlen.3, strnlen.3, strsep.3, strstr.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, termios.3, tsearch.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscat.3, wcscpy.3, wcslen.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcsrtombs.3, wcsstr.3, wcstok.3, wcstombs.3, wcwidth.3, wprintf.3, console_codes.4, dsp56k.4, full.4, initrd.4, loop.4, vcs.4, charmap.5, core.5, elf.5, locale.5, proc.5, repertoiremap.5, sysfs.5, termcap.5, aio.7, bpf-helpers.7, cgroups.7, charsets.7, complex.7, fanotify.7, feature_test_macros.7, inotify.7, locale.7, man-pages.7, man.7, pkeys.7, pthreads.7, rtld-audit.7, sock_diag.7, unix.7, user_namespaces.7, utf-8.7: Use '\e' rather than '\\' to get a backslash
Quoting Branden:
*roff escape sequences may sometimes look like C escapes, but that
is misleading. *roff is in part a macro language and that means
recursive expansion to arbitrary depths.
You can get away with "\\" in a context where no macro expansion
is taking place, but try to spell a literal backslash this way in
the argument to a macro and you will likely be unhappy with
results.
Try viewing the attached file with "man -l".
"\e" is the preferred and portable way to get a portable "escape
literal" going back to CSTR #54, the original Bell Labs troff
paper.
groff(7) discusses the issue:
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode. For a
printable backslash, use \e, or even better \[rs], to be
independent from the current escape character.
As of groff 1.22.4, groff_man(7) does as well:
\e Widely used in man pages to represent a backslash output
glyph. It works reliably as long as the .ec request is
not used, which should never happen in man pages, and it
is slightly more portable than the more exact ‘\(rs’
(“reverse solidus”) escape sequence.
People not concerned with portability to extremely old troffs should
probably just use \(rs (or \[rs]), as it means "the backslash
glyph", not "the glyph corresponding to whatever the current escape
character is".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2019-02-27 11:57:17 +00:00
|
|
|
printf("Child writing %s to efd\en", argv[j]);
|
2008-02-11 11:40:03 +00:00
|
|
|
u = strtoull(argv[j], NULL, 0);
|
|
|
|
/* strtoull() allows various bases */
|
|
|
|
s = write(efd, &u, sizeof(uint64_t));
|
|
|
|
if (s != sizeof(uint64_t))
|
|
|
|
handle_error("write");
|
|
|
|
}
|
locale.1, memusage.1, pldd.1, _syscall.2, add_key.2, bind.2, bpf.2, chown.2, clone.2, copy_file_range.2, eventfd.2, execve.2, futex.2, getdents.2, getrlimit.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, kexec_load.2, keyctl.2, listxattr.2, lseek.2, membarrier.2, memfd_create.2, mmap.2, mprotect.2, msgop.2, open_by_handle_at.2, perf_event_open.2, pipe.2, readdir.2, readlink.2, readv.2, recvmmsg.2, request_key.2, sched_setaffinity.2, seccomp.2, select.2, select_tut.2, sendmmsg.2, setns.2, signalfd.2, spu_run.2, stat.2, sysctl.2, tee.2, timer_create.2, timerfd_create.2, truncate.2, uname.2, unshare.2, userfaultfd.2, ustat.2, wait.2, CPU_SET.3, __ppc_get_timebase.3, argz_add.3, asprintf.3, backtrace.3, basename.3, bswap.3, bzero.3, cacos.3, cacosh.3, catan.3, catanh.3, catgets.3, clock_getcpuclockid.3, confstr.3, ctime.3, dl_iterate_phdr.3, dlinfo.3, duplocale.3, encrypt.3, end.3, endian.3, fgetws.3, fmemopen.3, fopencookie.3, fputws.3, frexp.3, ftw.3, get_nprocs_conf.3, get_phys_pages.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrouplist.3, getifaddrs.3, getline.3, getlogin.3, getopt.3, getpass.3, getprotoent_r.3, getpwnam.3, getservent_r.3, getsubopt.3, glob.3, gnu_get_libc_version.3, hsearch.3, if_nameindex.3, index.3, inet.3, inet_net_pton.3, inet_pton.3, insque.3, iswblank.3, iswspace.3, makecontext.3, mallinfo.3, malloc_hook.3, malloc_info.3, mallopt.3, matherr.3, mbrtowc.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, mcheck.3, memchr.3, mq_getattr.3, mq_notify.3, newlocale.3, nl_langinfo.3, offsetof.3, perror.3, posix_spawn.3, printf.3, pthread_attr_init.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_create.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_mutexattr_setrobust.3, pthread_setaffinity_np.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_sigmask.3, qsort.3, rand.3, readdir.3, regex.3, rpmatch.3, rtime.3, scanf.3, sem_wait.3, setaliasent.3, setbuf.3, stpcpy.3, stpncpy.3, strcat.3, strchr.3, strcpy.3, strdup.3, strerror.3, strfromd.3, strftime.3, strlen.3, strnlen.3, strsep.3, strstr.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, termios.3, tsearch.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscat.3, wcscpy.3, wcslen.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcsrtombs.3, wcsstr.3, wcstok.3, wcstombs.3, wcwidth.3, wprintf.3, console_codes.4, dsp56k.4, full.4, initrd.4, loop.4, vcs.4, charmap.5, core.5, elf.5, locale.5, proc.5, repertoiremap.5, sysfs.5, termcap.5, aio.7, bpf-helpers.7, cgroups.7, charsets.7, complex.7, fanotify.7, feature_test_macros.7, inotify.7, locale.7, man-pages.7, man.7, pkeys.7, pthreads.7, rtld-audit.7, sock_diag.7, unix.7, user_namespaces.7, utf-8.7: Use '\e' rather than '\\' to get a backslash
Quoting Branden:
*roff escape sequences may sometimes look like C escapes, but that
is misleading. *roff is in part a macro language and that means
recursive expansion to arbitrary depths.
You can get away with "\\" in a context where no macro expansion
is taking place, but try to spell a literal backslash this way in
the argument to a macro and you will likely be unhappy with
results.
Try viewing the attached file with "man -l".
"\e" is the preferred and portable way to get a portable "escape
literal" going back to CSTR #54, the original Bell Labs troff
paper.
groff(7) discusses the issue:
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode. For a
printable backslash, use \e, or even better \[rs], to be
independent from the current escape character.
As of groff 1.22.4, groff_man(7) does as well:
\e Widely used in man pages to represent a backslash output
glyph. It works reliably as long as the .ec request is
not used, which should never happen in man pages, and it
is slightly more portable than the more exact ‘\(rs’
(“reverse solidus”) escape sequence.
People not concerned with portability to extremely old troffs should
probably just use \(rs (or \[rs]), as it means "the backslash
glyph", not "the glyph corresponding to whatever the current escape
character is".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2019-02-27 11:57:17 +00:00
|
|
|
printf("Child completed write loop\en");
|
2008-02-11 11:40:03 +00:00
|
|
|
|
|
|
|
exit(EXIT_SUCCESS);
|
|
|
|
|
|
|
|
default:
|
|
|
|
sleep(2);
|
|
|
|
|
locale.1, memusage.1, pldd.1, _syscall.2, add_key.2, bind.2, bpf.2, chown.2, clone.2, copy_file_range.2, eventfd.2, execve.2, futex.2, getdents.2, getrlimit.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, kexec_load.2, keyctl.2, listxattr.2, lseek.2, membarrier.2, memfd_create.2, mmap.2, mprotect.2, msgop.2, open_by_handle_at.2, perf_event_open.2, pipe.2, readdir.2, readlink.2, readv.2, recvmmsg.2, request_key.2, sched_setaffinity.2, seccomp.2, select.2, select_tut.2, sendmmsg.2, setns.2, signalfd.2, spu_run.2, stat.2, sysctl.2, tee.2, timer_create.2, timerfd_create.2, truncate.2, uname.2, unshare.2, userfaultfd.2, ustat.2, wait.2, CPU_SET.3, __ppc_get_timebase.3, argz_add.3, asprintf.3, backtrace.3, basename.3, bswap.3, bzero.3, cacos.3, cacosh.3, catan.3, catanh.3, catgets.3, clock_getcpuclockid.3, confstr.3, ctime.3, dl_iterate_phdr.3, dlinfo.3, duplocale.3, encrypt.3, end.3, endian.3, fgetws.3, fmemopen.3, fopencookie.3, fputws.3, frexp.3, ftw.3, get_nprocs_conf.3, get_phys_pages.3, getaddrinfo.3, getaddrinfo_a.3, getdate.3, getgrouplist.3, getifaddrs.3, getline.3, getlogin.3, getopt.3, getpass.3, getprotoent_r.3, getpwnam.3, getservent_r.3, getsubopt.3, glob.3, gnu_get_libc_version.3, hsearch.3, if_nameindex.3, index.3, inet.3, inet_net_pton.3, inet_pton.3, insque.3, iswblank.3, iswspace.3, makecontext.3, mallinfo.3, malloc_hook.3, malloc_info.3, mallopt.3, matherr.3, mbrtowc.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, mcheck.3, memchr.3, mq_getattr.3, mq_notify.3, newlocale.3, nl_langinfo.3, offsetof.3, perror.3, posix_spawn.3, printf.3, pthread_attr_init.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_create.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_mutexattr_setrobust.3, pthread_setaffinity_np.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_sigmask.3, qsort.3, rand.3, readdir.3, regex.3, rpmatch.3, rtime.3, scanf.3, sem_wait.3, setaliasent.3, setbuf.3, stpcpy.3, stpncpy.3, strcat.3, strchr.3, strcpy.3, strdup.3, strerror.3, strfromd.3, strftime.3, strlen.3, strnlen.3, strsep.3, strstr.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, termios.3, tsearch.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscat.3, wcscpy.3, wcslen.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcsrtombs.3, wcsstr.3, wcstok.3, wcstombs.3, wcwidth.3, wprintf.3, console_codes.4, dsp56k.4, full.4, initrd.4, loop.4, vcs.4, charmap.5, core.5, elf.5, locale.5, proc.5, repertoiremap.5, sysfs.5, termcap.5, aio.7, bpf-helpers.7, cgroups.7, charsets.7, complex.7, fanotify.7, feature_test_macros.7, inotify.7, locale.7, man-pages.7, man.7, pkeys.7, pthreads.7, rtld-audit.7, sock_diag.7, unix.7, user_namespaces.7, utf-8.7: Use '\e' rather than '\\' to get a backslash
Quoting Branden:
*roff escape sequences may sometimes look like C escapes, but that
is misleading. *roff is in part a macro language and that means
recursive expansion to arbitrary depths.
You can get away with "\\" in a context where no macro expansion
is taking place, but try to spell a literal backslash this way in
the argument to a macro and you will likely be unhappy with
results.
Try viewing the attached file with "man -l".
"\e" is the preferred and portable way to get a portable "escape
literal" going back to CSTR #54, the original Bell Labs troff
paper.
groff(7) discusses the issue:
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode. For a
printable backslash, use \e, or even better \[rs], to be
independent from the current escape character.
As of groff 1.22.4, groff_man(7) does as well:
\e Widely used in man pages to represent a backslash output
glyph. It works reliably as long as the .ec request is
not used, which should never happen in man pages, and it
is slightly more portable than the more exact ‘\(rs’
(“reverse solidus”) escape sequence.
People not concerned with portability to extremely old troffs should
probably just use \(rs (or \[rs]), as it means "the backslash
glyph", not "the glyph corresponding to whatever the current escape
character is".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2019-02-27 11:57:17 +00:00
|
|
|
printf("Parent about to read\en");
|
2008-02-11 11:40:03 +00:00
|
|
|
s = read(efd, &u, sizeof(uint64_t));
|
|
|
|
if (s != sizeof(uint64_t))
|
|
|
|
handle_error("read");
|
eventfd.2, mprotect.2, pidfd_open.2, spu_run.2, timer_create.2, bswap.3, dl_iterate_phdr.3, endian.3, pthread_attr_init.3, pthread_getattr_np.3, vcs.4, rtld-audit.7: In printf(): s/0x%/%#/ except when followed by X instead of x
Use printf()'s '#' flag character to prepend the string "0x".
However, when the number is printed in uppercase, and the prefix
is in lowercase, the string "0x" needs to be manually written.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2020-09-11 20:53:51 +00:00
|
|
|
printf("Parent read %"PRIu64" (%#"PRIx64") from efd\en", u, u);
|
2008-02-11 11:40:03 +00:00
|
|
|
exit(EXIT_SUCCESS);
|
|
|
|
|
|
|
|
case \-1:
|
|
|
|
handle_error("fork");
|
|
|
|
}
|
|
|
|
}
|
memusage.1, clone.2, eventfd.2, futex.2, getdents.2, ioctl_fat.2, ioctl_ns.2, kcmp.2, keyctl.2, mmap.2, mprotect.2, msgop.2, recvmmsg.2, request_key.2, sched_setaffinity.2, seccomp.2, setns.2, tee.2, timer_create.2, timerfd_create.2, unshare.2, userfaultfd.2, wait.2, __ppc_get_timebase.3, backtrace.3, bswap.3, clock_getcpuclockid.3, dl_iterate_phdr.3, dlinfo.3, dlopen.3, duplocale.3, end.3, endian.3, fmemopen.3, fopencookie.3, frexp.3, ftw.3, getdate.3, getgrouplist.3, getifaddrs.3, getprotoent_r.3, getservent_r.3, gnu_get_libc_version.3, if_nameindex.3, inet.3, inet_net_pton.3, inet_pton.3, insque.3, makecontext.3, mallinfo.3, malloc_info.3, mallopt.3, matherr.3, mbstowcs.3, mcheck.3, mq_getattr.3, mq_notify.3, newlocale.3, offsetof.3, posix_spawn.3, pthread_attr_init.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_create.3, pthread_getattr_default_np.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_setname_np.3, pthread_setschedparam.3, pthread_sigmask.3, scandir.3, sem_wait.3, strcat.3, strftime.3, strtok.3, strtol.3, strverscmp.3, loop.4, core.5, aio.7, fanotify.7, feature_test_macros.7, inotify.7, pkeys.7, unix.7, user_namespaces.7: Use .EX/.EE for EXAMPLE programs
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-16 08:44:33 +00:00
|
|
|
.EE
|
getent.1, intro.1, time.1, _exit.2, _syscall.2, accept.2, access.2, acct.2, adjtimex.2, alarm.2, alloc_hugepages.2, arch_prctl.2, bdflush.2, bind.2, brk.2, cacheflush.2, capget.2, chdir.2, chmod.2, chown.2, chroot.2, clock_getres.2, clock_nanosleep.2, clone.2, close.2, connect.2, create_module.2, delete_module.2, dup.2, epoll_create.2, epoll_ctl.2, epoll_wait.2, eventfd.2, execve.2, exit_group.2, faccessat.2, fchmodat.2, fchownat.2, fcntl.2, flock.2, fork.2, fstatat.2, fsync.2, futex.2, futimesat.2, get_kernel_syms.2, get_robust_list.2, get_thread_area.2, getcpu.2, getdents.2, getdomainname.2, getgid.2, getgroups.2, gethostname.2, getitimer.2, getpagesize.2, getpeername.2, getpid.2, getpriority.2, getresuid.2, getrlimit.2, getrusage.2, getsid.2, getsockname.2, getsockopt.2, gettid.2, gettimeofday.2, getuid.2, getunwind.2, getxattr.2, idle.2, init_module.2, inotify_add_watch.2, inotify_init.2, inotify_rm_watch.2, intro.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl.2, ioctl_list.2, ioperm.2, iopl.2, ioprio_set.2, ipc.2, kcmp.2, kill.2, killpg.2, link.2, linkat.2, listen.2, listxattr.2, llseek.2, lookup_dcookie.2, lseek.2, madvise.2, migrate_pages.2, mincore.2, mkdir.2, mkdirat.2, mknod.2, mknodat.2, mlock.2, mmap.2, mmap2.2, modify_ldt.2, mount.2, move_pages.2, mprotect.2, mq_getsetattr.2, mremap.2, msgctl.2, msgget.2, msgop.2, msync.2, nanosleep.2, nfsservctl.2, nice.2, open.2, openat.2, outb.2, pause.2, pciconfig_read.2, perf_event_open.2, perfmonctl.2, personality.2, pipe.2, pivot_root.2, poll.2, posix_fadvise.2, prctl.2, pread.2, process_vm_readv.2, ptrace.2, query_module.2, quotactl.2, read.2, readahead.2, readdir.2, readlink.2, readlinkat.2, readv.2, reboot.2, recv.2, remap_file_pages.2, removexattr.2, rename.2, renameat.2, rmdir.2, rt_sigqueueinfo.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setaffinity.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, select.2, semctl.2, semget.2, semop.2, send.2, sendfile.2, set_thread_area.2, set_tid_address.2, seteuid.2, setfsgid.2, setfsuid.2, setgid.2, setpgid.2, setresuid.2, setreuid.2, setsid.2, setuid.2, setup.2, setxattr.2, shmctl.2, shmget.2, shmop.2, shutdown.2, sigaction.2, sigaltstack.2, signal.2, signalfd.2, sigpending.2, sigprocmask.2, sigreturn.2, sigsuspend.2, sigwaitinfo.2, socket.2, socketcall.2, socketpair.2, splice.2, stat.2, statfs.2, stime.2, swapon.2, symlink.2, symlinkat.2, sync.2, sync_file_range.2, sysctl.2, sysfs.2, sysinfo.2, syslog.2, tee.2, time.2, timerfd_create.2, times.2, tkill.2, truncate.2, umask.2, umount.2, uname.2, unimplemented.2, unlink.2, unlinkat.2, uselib.2, ustat.2, utime.2, utimensat.2, vfork.2, vhangup.2, vm86.2, vmsplice.2, wait.2, wait4.2, write.2, CPU_SET.3, INFINITY.3, MB_CUR_MAX.3, MB_LEN_MAX.3, __setfpucw.3, a64l.3, abort.3, abs.3, acos.3, acosh.3, addseverity.3, adjtime.3, aio_cancel.3, aio_error.3, aio_fsync.3, aio_read.3, aio_return.3, aio_suspend.3, aio_write.3, alloca.3, argz_add.3, asin.3, asinh.3, asprintf.3, assert.3, assert_perror.3, atan.3, atan2.3, atanh.3, atexit.3, atof.3, atoi.3, backtrace.3, basename.3, bcmp.3, bcopy.3, bindresvport.3, bsd_signal.3, bsearch.3, bstring.3, btowc.3, btree.3, byteorder.3, bzero.3, cabs.3, cacos.3, cacosh.3, canonicalize_file_name.3, carg.3, casin.3, casinh.3, catan.3, catanh.3, catgets.3, catopen.3, cbrt.3, ccos.3, ccosh.3, ceil.3, cerf.3, cexp.3, cexp2.3, cfree.3, cimag.3, clearenv.3, clock.3, clock_getcpuclockid.3, clog.3, clog10.3, clog2.3, closedir.3, cmsg.3, confstr.3, conj.3, copysign.3, cos.3, cosh.3, cpow.3, cproj.3, creal.3, crypt.3, csin.3, csinh.3, csqrt.3, ctan.3, ctanh.3, ctermid.3, ctime.3, daemon.3, dbopen.3, des_crypt.3, difftime.3, dirfd.3, div.3, dl_iterate_phdr.3, dlopen.3, dprintf.3, drand48.3, drand48_r.3, dysize.3, ecvt.3, ecvt_r.3, encrypt.3, end.3, endian.3, envz_add.3, erf.3, erfc.3, err.3, errno.3, error.3, ether_aton.3, euidaccess.3, exec.3, exit.3, exp.3, exp10.3, exp2.3, expm1.3, fabs.3, fclose.3, fcloseall.3, fdim.3, fenv.3, ferror.3, fexecve.3, fflush.3, ffs.3, fgetgrent.3, fgetpwent.3, fgetwc.3, fgetws.3, finite.3, flockfile.3, floor.3, fma.3, fmax.3, fmemopen.3, fmin.3, fmod.3, fmtmsg.3, fnmatch.3, fopen.3, fpathconf.3, fpclassify.3, fpurge.3, fputwc.3, fputws.3, fread.3, frexp.3, fseek.3, fseeko.3, ftime.3, ftok.3, fts.3, ftw.3, futimes.3, fwide.3, gamma.3, gcvt.3, getaddrinfo.3, getaddrinfo_a.3, getauxval.3, getcontext.3, getcwd.3, getdate.3, getdirentries.3, getdtablesize.3, getenv.3, getfsent.3, getgrent.3, getgrent_r.3, getgrnam.3, getgrouplist.3, gethostbyname.3, gethostid.3, getipnodebyname.3, getline.3, getloadavg.3, getlogin.3, getmntent.3, getnameinfo.3, getnetent.3, getnetent_r.3, getopt.3, getpass.3, getprotoent.3, getprotoent_r.3, getpt.3, getpw.3, getpwent.3, getpwent_r.3, getpwnam.3, getrpcent.3, getrpcent_r.3, getrpcport.3, gets.3, getservent.3, getservent_r.3, getspnam.3, getttyent.3, getumask.3, getusershell.3, getutent.3, getw.3, getwchar.3, glob.3, grantpt.3, gsignal.3, hash.3, hsearch.3, hypot.3, iconv.3, iconv_close.3, iconv_open.3, ilogb.3, index.3, inet.3, inet_ntop.3, inet_pton.3, infnan.3, initgroups.3, insque.3, intro.3, isalpha.3, isatty.3, isgreater.3, iswalnum.3, iswalpha.3, iswblank.3, iswcntrl.3, iswctype.3, iswdigit.3, iswgraph.3, iswlower.3, iswprint.3, iswpunct.3, iswspace.3, iswupper.3, iswxdigit.3, j0.3, key_setsecret.3, ldexp.3, lgamma.3, lio_listio.3, localeconv.3, lockf.3, log.3, log10.3, log1p.3, log2.3, logb.3, login.3, longjmp.3, lrint.3, lround.3, lsearch.3, lseek64.3, makecontext.3, makedev.3, malloc.3, malloc_hook.3, mblen.3, mbrlen.3, mbrtowc.3, mbsinit.3, mbsnrtowcs.3, mbsrtowcs.3, mbstowcs.3, mbtowc.3, memccpy.3, memchr.3, memcmp.3, memcpy.3, memfrob.3, memmem.3, memmove.3, mempcpy.3, memset.3, mkdtemp.3, mkfifo.3, mkfifoat.3, mkstemp.3, mktemp.3, modf.3, mpool.3, mq_close.3, mq_getattr.3, mq_notify.3, mq_open.3, mq_receive.3, mq_send.3, mq_unlink.3, mtrace.3, nan.3, netlink.3, nextafter.3, nl_langinfo.3, offsetof.3, on_exit.3, opendir.3, openpty.3, perror.3, popen.3, posix_fallocate.3, posix_memalign.3, posix_openpt.3, pow.3, pow10.3, printf.3, profil.3, program_invocation_name.3, psignal.3, pthread_kill_other_threads_np.3, ptsname.3, putenv.3, putgrent.3, putpwent.3, puts.3, putwchar.3, qecvt.3, qsort.3, queue.3, raise.3, rand.3, random.3, random_r.3, rcmd.3, re_comp.3, readdir.3, realpath.3, recno.3, regex.3, remainder.3, remove.3, remquo.3, resolver.3, rewinddir.3, rexec.3, rint.3, round.3, rpc.3, rpmatch.3, rtime.3, rtnetlink.3, scalb.3, scalbln.3, scandir.3, scandirat.3, scanf.3, seekdir.3, sem_close.3, sem_destroy.3, sem_getvalue.3, sem_init.3, sem_open.3, sem_post.3, sem_unlink.3, sem_wait.3, setaliasent.3, setbuf.3, setenv.3, setjmp.3, setlocale.3, setlogmask.3, setnetgrent.3, shm_open.3, siginterrupt.3, signbit.3, significand.3, sigpause.3, sigqueue.3, sigset.3, sigsetops.3, sigvec.3, sin.3, sincos.3, sinh.3, sleep.3, sockatmark.3, sqrt.3, statvfs.3, stdarg.3, stdin.3, stdio.3, stdio_ext.3, stpcpy.3, stpncpy.3, strcasecmp.3, strcat.3, strchr.3, strcmp.3, strcoll.3, strcpy.3, strdup.3, strerror.3, strfmon.3, strfry.3, strftime.3, string.3, strlen.3, strnlen.3, strpbrk.3, strptime.3, strsep.3, strsignal.3, strspn.3, strstr.3, strtod.3, strtoimax.3, strtok.3, strtol.3, strtoul.3, strverscmp.3, strxfrm.3, swab.3, sysconf.3, syslog.3, system.3, sysv_signal.3, tan.3, tanh.3, tcgetpgrp.3, tcgetsid.3, telldir.3, tempnam.3, termios.3, tgamma.3, timegm.3, timeradd.3, tmpfile.3, tmpnam.3, toascii.3, toupper.3, towctrans.3, towlower.3, towupper.3, trunc.3, tsearch.3, ttyname.3, ttyslot.3, tzset.3, ualarm.3, ulimit.3, ungetwc.3, unlocked_stdio.3, unlockpt.3, updwtmp.3, usleep.3, wcpcpy.3, wcpncpy.3, wcrtomb.3, wcscasecmp.3, wcscat.3, wcschr.3, wcscmp.3, wcscpy.3, wcscspn.3, wcsdup.3, wcslen.3, wcsncasecmp.3, wcsncat.3, wcsncmp.3, wcsncpy.3, wcsnlen.3, wcsnrtombs.3, wcspbrk.3, wcsrchr.3, wcsrtombs.3, wcsspn.3, wcsstr.3, wcstoimax.3, wcstok.3, wcstombs.3, wcswidth.3, wctob.3, wctomb.3, wctrans.3, wctype.3, wcwidth.3, wmemchr.3, wmemcmp.3, wmemcpy.3, wmemmove.3, wmemset.3, wordexp.3, wprintf.3, xcrypt.3, xdr.3, y0.3, cciss.4, console.4, console_codes.4, console_ioctl.4, dsp56k.4, fd.4, full.4, hd.4, hpsa.4, initrd.4, intro.4, lp.4, mem.4, mouse.4, null.4, pts.4, ram.4, random.4, rtc.4, sk98lin.4, st.4, tty.4, ttyS.4, tty_ioctl.4, vcs.4, wavelan.4, acct.5, charmap.5, dir_colors.5, filesystems.5, ftpusers.5, group.5, host.conf.5, hosts.5, hosts.equiv.5, intro.5, issue.5, locale.5, motd.5, networks.5, nologin.5, nscd.conf.5, passwd.5, proc.5, protocols.5, resolv.conf.5, rpc.5, securetty.5, services.5, shells.5, termcap.5, ttytype.5, utmp.5, armscii-8.7, arp.7, ascii.7, bootparam.7, capabilities.7, charsets.7, complex.7, cp1251.7, credentials.7, ddp.7, environ.7, epoll.7, fifo.7, futex.7, glob.7, hier.7, icmp.7, inotify.7, intro.7, ip.7, ipv6.7, iso_8859-1.7, iso_8859-10.7, iso_8859-11.7, iso_8859-13.7, iso_8859-14.7, iso_8859-15.7, iso_8859-16.7, iso_8859-2.7, iso_8859-3.7, iso_8859-4.7, iso_8859-5.7, iso_8859-6.7, iso_8859-7.7, iso_8859-8.7, iso_8859-9.7, koi8-r.7, koi8-u.7, locale.7, mailaddr.7, man.7, mq_overview.7, netdevice.7, netlink.7, numa.7, packet.7, path_resolution.7, pipe.7, posixoptions.7, pthreads.7, pty.7, raw.7, regex.7, rtld-audit.7, rtnetlink.7, sem_overview.7, shm_overview.7, sigevent.7, signal.7, socket.7, standards.7, suffixes.7, svipc.7, tcp.7, termio.7, time.7, udp.7, udplite.7, unicode.7, unix.7, uri.7, utf-8.7, x25.7, nscd.8, sync.8, tzselect.8, zdump.8, zic.8: Global fix: remove unneeded double quotes in .SH headings
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-02-24 18:01:36 +00:00
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.SH SEE ALSO
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2008-02-11 11:40:03 +00:00
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.BR futex (2),
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.BR pipe (2),
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.BR poll (2),
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.BR read (2),
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.BR select (2),
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.BR signalfd (2),
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.BR timerfd_create (2),
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.BR write (2),
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.BR epoll (7),
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.BR sem_overview (7)
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