NAME
getdtablesize - get descriptor table size SYNOPSIS
#include
int getdtablesize(void); Feature Test Macro Requirements for glibc (see featuretestmacros(7)): getdtablesize(): Since glibc 2.12: BSDSOURCE || !(POSIXCSOURCE >= 200112L || XOPENSOURCE >= 600) Before glibc 2.12: BSDSOURCE || XOPENSOURCE >= 500 || XOPENSOURCE && XOPENSOURCEEXTENDED 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.1-2001; portable applications should employ sysconf(SCOPENMAX) instead of this call. NOTES getdtablesize() is implemented as a libc library function. The glibc version calls getrlimit(2) and returns the current RLIMITNOFILE limit, or OPENMAX when that fails. The libc4 and libc5 versions return OPENMAX (set to 256 since Linux 0.98.4). SEE ALSO close(2), dup(2), getrlimit(2), open(2) COLOPHON
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Linux 2013-02-05 GETDTABLESIZE(3)