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

NAME

     getdtablesize - get file 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:
             /* Glibc since 2.19: */ _DEFAULT_SOURCE
                 || /* Glibc versions <= 2.19: */ _BSD_SOURCE
                 || ! (_POSIX_C_SOURCE >= 200112L)
         Before glibc 2.12:
             _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.

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 getrlimit(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

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     description  of  the project, information about reporting bugs, and the
     latest    version    of    this    page,    can     be     found     at
     https://www.kernel.org/doc/man-pages/.

Linux 2016-03-15 GETDTABLESIZE(3)