mirror of https://github.com/mkerrisk/man-pages
107 lines
2.8 KiB
Groff
107 lines
2.8 KiB
Groff
.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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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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.\"
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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.\" manual page may be incorrect or out-of-date.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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.\"
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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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.\" %%%LICENSE_END
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.\"
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.\" Modified 2002-04-15 by Roger Luethi <rl@hellgate.ch> and aeb
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.\"
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.TH GETDTABLESIZE 3 2015-03-02 "Linux" "Linux Programmer's Manual"
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.SH NAME
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getdtablesize \- get file descriptor table size
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.SH SYNOPSIS
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.B #include <unistd.h>
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.sp
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.B int getdtablesize(void);
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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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.BR getdtablesize ():
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.ad l
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.RS 4
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.PD 0
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.TP 4
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Since glibc 2.12:
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.nf
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_BSD_SOURCE ||
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!(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600)
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.TP 4
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.fi
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Before glibc 2.12:
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_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
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_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
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.PD
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.RE
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.ad b
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.SH DESCRIPTION
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.BR getdtablesize ()
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returns the maximum number of files a process can have open,
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one more than the largest possible value for a file descriptor.
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.SH RETURN VALUE
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The current limit on the number of open files per process.
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.SH ERRORS
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On Linux,
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.BR getdtablesize ()
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can return any of the errors described for
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.BR getrlimit (2);
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see NOTES below.
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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 getdtablesize ()
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T} Thread safety MT-Safe
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.TE
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.SH CONFORMING TO
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SVr4, 4.4BSD (the
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.BR getdtablesize ()
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function first appeared in 4.2BSD).
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It is not specified in POSIX.1;
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portable applications should employ
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.I sysconf(_SC_OPEN_MAX)
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instead of this call.
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.SH NOTES
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.BR getdtablesize ()
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is implemented as a libc library function.
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The glibc version calls
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.BR getrlimit (2)
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and returns the current
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.B RLIMIT_NOFILE
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limit, or
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.B OPEN_MAX
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when that fails.
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.\" The libc4 and libc5 versions return
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.\" .B OPEN_MAX
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.\" (set to 256 since Linux 0.98.4).
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.SH SEE ALSO
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.BR close (2),
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.BR dup (2),
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.BR getrlimit (2),
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.BR open (2)
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