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getdtablesize(3) — Linux manual page

getdtablesize(3) Library Functions Manual getdtablesize(3)

NAME top

 getdtablesize - get file descriptor table size

LIBRARY top

 Standard C library (libc, -lc)

SYNOPSIS top

 #include <unistd.h>
 int getdtablesize(void);
 Feature Test Macro Requirements for glibc (see
 feature_test_macros(7)):
 getdtablesize():
 Since glibc 2.20:
 _DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
 glibc 2.12 to glibc 2.19:
 _BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
 Before glibc 2.12:
 _BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION top

 getdtablesize() returns the maximum number of files a process can
 have open, one more than the largest possible value for a file
 descriptor.

RETURN VALUE top

 The current limit on the number of open files per process.

ERRORS top

 On Linux, getdtablesize() can return any of the errors described
 for getrlimit(2); see VERSIONS below.

ATTRIBUTES top

 For an explanation of the terms used in this section, see
 attributes(7).
 ┌──────────────────────────────────────┬───────────────┬─────────┐
 │ Interface │ Attribute │ Value │
 ├──────────────────────────────────────┼───────────────┼─────────┤
 │ getdtablesize() │ Thread safety │ MT-Safe │
 └──────────────────────────────────────┴───────────────┴─────────┘

VERSIONS top

 The glibc version of getdtablesize() calls getrlimit(2) and
 returns the current RLIMIT_NOFILE limit, or OPEN_MAX when that
 fails.
 Portable applications should employ sysconf(_SC_OPEN_MAX) instead
 of this call.

STANDARDS top

 None.

HISTORY top

 SVr4, 4.4BSD (first appeared in 4.2BSD).

SEE ALSO top

 close(2), dup(2), getrlimit(2), open(2)

COLOPHON top

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 user-space interface documentation) project. Information about
 the project can be found at 
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 for this manual page, see
 ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
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 man-pages@man7.org
Linux man-pages 6.10 2024年07月23日 getdtablesize(3)

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