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getdtablesize(3) Library Functions Manual getdtablesize(3)
getdtablesize - get file descriptor table size
Standard C library (libc, -lc)
#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
getdtablesize() returns the maximum number of files a process can have open, one more than the largest possible value for a file descriptor.
The current limit on the number of open files per process.
On Linux, getdtablesize() can return any of the errors described for getrlimit(2); see NOTES below.
For an explanation of the terms used in this section, see attributes(7). ┌─────────────────────────────────────┬───────────────┬─────────┐ │ Interface │ Attribute │ Value │ ├─────────────────────────────────────┼───────────────┼─────────┤ │ getdtablesize() │ Thread safety │ MT-Safe │ └─────────────────────────────────────┴───────────────┴─────────┘
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.
None.
SVr4, 4.4BSD (first appeared in 4.2BSD).
close(2), dup(2), getrlimit(2), open(2)
Linux man-pages (unreleased) (date) getdtablesize(3)