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 2.20:
               _DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
           Glibc 2.12 to 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

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