2004-11-03 13:51:07 +00:00
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.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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2008-03-17 12:06:58 +00:00
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.\" and Copyright (C) 2004, 2007 Michael kerrisk <mtk.manpages@gmail.com>
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2004-11-03 13:51:07 +00:00
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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2007-04-12 22:42:49 +00:00
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sat Jul 24 18:20:58 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified Fri Feb 14 21:47:50 1997 by Andries Brouwer (aeb@cwi.nl)
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2007-09-20 06:52:22 +00:00
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.\" Modified 9 Jun 2004, Michael Kerrisk <mtk.manpages@gmail.com>
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2004-11-03 13:51:07 +00:00
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.\" Changed unsetenv() prototype; added EINVAL error
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accept.2, execve.2, futimesat.2, getresuid.2, getrlimit.2, madvise.2, mq_getsetattr.2, msgctl.2, nice.2, open.2, poll.2, setresuid.2, shmctl.2, sigaction.2, times.2, utimensat.2, __setfpucw.3, atoi.3, endian.3, err.3, euidaccess.3, fenv.3, fopencookie.3, fpurge.3, getgrouplist.3, getutmp.3, j0.3, lgamma.3, netlink.3, pthread_attr_init.3, pthread_attr_setaffinity_np.3, pthread_cleanup_push_defer_np.3, pthread_getattr_np.3, pthread_kill_other_threads_np.3, pthread_setaffinity_np.3, pthread_tryjoin_np.3, pthread_yield.3, random_r.3, readdir.3, rtnetlink.3, scanf.3, setenv.3, significand.3, sigsetops.3, strerror.3, strstr.3, sysv_signal.3, termios.3, timegm.3, unlocked_stdio.3, y0.3, locale.5, bootparam.7, feature_test_macros.7, ip.7, locale.7, pthreads.7, rtld-audit.7, nscd.8: Global fix: s/non-standard/nonstandard/
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 16:37:52 +00:00
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.\" Noted nonstandard behavior of setenv() if name contains '='
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2005-08-12 11:41:25 +00:00
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.\" 2005-08-12, mtk, glibc 2.3.4 fixed the "name contains '='" bug
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.\"
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2009-09-20 02:56:47 +00:00
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.TH SETENV 3 2009-09-20 "GNU" "Linux Programmer's Manual"
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.SH NAME
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setenv \- change or add an environment variable
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.SH SYNOPSIS
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.nf
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.B #include <stdlib.h>
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.sp
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.BI "int setenv(const char *" name ", const char *" value ", int " overwrite );
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.sp
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.BI "int unsetenv(const char *" name );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.ad l
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.BR setenv (),
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.BR unsetenv ():
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.RS 4
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_BSD_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600
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.RE
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.ad b
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.SH DESCRIPTION
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The
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.BR setenv ()
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function adds the variable \fIname\fP to the
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environment with the value \fIvalue\fP, if \fIname\fP does not
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already exist.
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If \fIname\fP does exist in the environment, then
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intro.1, time.1, adjtimex.2, capget.2, eventfd.2, fcntl.2, getrlimit.2, getsockopt.2, gettimeofday.2, intro.2, ioctl_list.2, ioperm.2, mlock.2, pivot_root.2, poll.2, prctl.2, ptrace.2, sched_setscheduler.2, select_tut.2, semget.2, sigaltstack.2, signalfd.2, sysctl.2, timer_settime.2, timerfd_create.2, wait.2, CPU_SET.3, argz_add.3, assert_perror.3, atexit.3, backtrace.3, bcmp.3, clearenv.3, ctime.3, dl_iterate_phdr.3, dlopen.3, ecvt.3, errno.3, error.3, ether_aton.3, exit.3, fenv.3, ferror.3, finite.3, flockfile.3, fnmatch.3, fpathconf.3, fpclassify.3, ftime.3, ftok.3, ftw.3, fwide.3, getaddrinfo.3, gethostbyname.3, getlogin.3, getnameinfo.3, getnetent.3, getopt.3, getprotoent.3, getrpcent.3, getservent.3, glob.3, hsearch.3, inet.3, isalpha.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, longjmp.3, lsearch.3, malloc.3, matherr.3, mblen.3, mbsinit.3, mbtowc.3, on_exit.3, printf.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_equal.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_setaffinity_np.3, pthread_setcancelstate.3, pthread_setconcurrency.3, pthread_setschedparam.3, pthread_setschedprio.3, ptsname.3, putenv.3, putgrent.3, raise.3, rcmd.3, regex.3, rexec.3, rpc.3, rpmatch.3, rtnetlink.3, scandir.3, sem_init.3, setaliasent.3, setbuf.3, setenv.3, setjmp.3, signbit.3, stdio_ext.3, strtod.3, strtol.3, strtoul.3, system.3, termios.3, timeradd.3, tzset.3, ualarm.3, wctomb.3, xdr.3, st.4, tty_ioctl.4, core.5, elf.5, proc.5, bootparam.7, capabilities.7, icmp.7, ip.7, ipv6.7, math_error.7, mdoc.samples.7, mq_overview.7, pthreads.7, raw.7, regex.7, socket.7, tcp.7, tzselect.8: Global fix: s/non-zero/nonzero/
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 16:40:55 +00:00
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its value is changed to \fIvalue\fP if \fIoverwrite\fP is nonzero;
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if \fIoverwrite\fP is zero, then the value of \fIname\fP is not
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changed.
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2008-03-17 12:06:58 +00:00
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This function makes copies of the strings pointed to by
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.I name
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and
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.I value
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(by contrast with
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.BR putenv (3)).
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.PP
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The
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.BR unsetenv ()
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function deletes the variable \fIname\fP from
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the environment.
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If
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.I name
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does not exist in the environment,
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then the function succeeds, and the environment is unchanged.
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.SH "RETURN VALUE"
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The
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.BR setenv ()
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function returns zero on success,
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or \-1 on error, with
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.I errno
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set to indicate the cause of the error.
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2007-05-12 09:06:04 +00:00
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The
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.BR unsetenv ()
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function returns zero on success,
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or \-1 on error, with
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.I errno
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set to indicate the cause of the error.
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.SH "ERRORS"
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.TP
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.B EINVAL
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.I name
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is NULL, points to a string of length 0,
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or contains an \(aq=\(aq character.
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.TP
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.B ENOMEM
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Insufficient memory to add a new variable to the environment.
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.SH "CONFORMING TO"
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4.3BSD, POSIX.1-2001.
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.SH "NOTES"
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2008-03-17 12:06:58 +00:00
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POSIX.1-2001 does not require
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.BR setenv ()
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or
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.BR unsetenv ()
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to be reentrant.
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2007-05-12 09:06:04 +00:00
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Prior to glibc 2.2.2,
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.BR unsetenv ()
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was prototyped
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as returning \fIvoid\fP; more recent glibc versions follow the
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2006-08-03 13:57:30 +00:00
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POSIX.1-2001-compliant prototype shown in the SYNOPSIS.
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.SH BUGS
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2006-08-03 13:57:30 +00:00
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POSIX.1-2001 specifies that if
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.I name
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contains an \(aq=\(aq character, then
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.BR setenv ()
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should fail with the error
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.BR EINVAL ;
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2008-06-09 15:49:35 +00:00
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however, versions of glibc before 2.3.4 allowed an \(aq=\(aq sign in
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.IR name .
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.SH "SEE ALSO"
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.BR clearenv (3),
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.BR getenv (3),
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.BR putenv (3),
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2006-04-21 00:45:46 +00:00
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.BR environ (7)
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