GETDTABLESIZE(2) - man page online | library functions

Get descriptor table size.

GETDTABLESIZE(3)                    Linux Programmer's Manual                    GETDTABLESIZE(3)

NAME getdtablesize - get descriptor table size
SYNOPSIS #include <unistd.h> int getdtablesize(void); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): getdtablesize(): Since glibc 2.12: _BSD_SOURCE || !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) Before glibc 2.12: _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
DESCRIPTION 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 The current limit on the number of open files per process.
ERRORS On Linux, getdtablesize() can return any of the errors described for getrlimit(2); see NOTES below.
ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). ┌────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├────────────────┼───────────────┼─────────┤ │getdtablesize() │ Thread safety │ MT-Safe │ └────────────────┴───────────────┴─────────┘
CONFORMING TO SVr4, 4.4BSD (the getdtablesize() function first appeared in 4.2BSD). It is not specified in POSIX.1; portable applications should employ sysconf(_SC_OPEN_MAX) instead of this call.
NOTES getdtablesize() is implemented as a libc library function. The glibc version calls getr‐ limit(2) and returns the current RLIMIT_NOFILE limit, or OPEN_MAX when that fails.
SEE ALSO close(2), dup(2), getrlimit(2), open(2)
COLOPHON This page is part of release 4.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at
Linux 2015-03-02 GETDTABLESIZE(3)
This manual Reference Other manuals
getdtablesize(2) referred by dup(2freebsd) | dup2(2freebsd) | errno(2freebsd) | fcntl(2freebsd) | getdtablesize(2freebsd) | intro(2freebsd) | open(2freebsd) | openat(2freebsd) | select(2freebsd)
refer to attributes(7) | close(2) | dup(2) | feature_test_macros(7) | getdtablesize(3) | getrlimit(2) | open(2)