GETDTABLESIZE(2) Linux Programmer s Manual GETDTABLESIZE(2)

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(): _BSD_SOURCE || _XOPEN_SOURCE >= 500

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.

CONFORMING TO SVr4, 4.4BSD (the getdtablesize() function first appeared in 4.2BSD). It is not specified in POSIX.1-2001; 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 getrlimit(2) and returns the current RLIMIT_NOFILE limit, or OPEN_MAX when that fails. The libc4 and libc5 versions return OPEN_MAX (set to 256 since Linux 0.98.4).

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

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

Linux 2007-07-26 GETDTABLESIZE(2)