getdtablesize - get file descriptor table size

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ getdtablesize()                                                             │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

getdtablesize()  returns  the  maximum number of files a process can have open, one more than the largest
       possible value for a file descriptor.

       On Linux, getdtablesize() can return any of the errors described for getrlimit(2); see VERSIONS below.

       SVr4, 4.4BSD (first appeared in 4.2BSD).

       Standard C library (libc, -lc)

       getdtablesize - get file descriptor table size

       The current limit on the number of open files per process.

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

Linux man-pages 6.9.1                              2024-06-16                                   getdtablesize(3)

       None.

#include<unistd.h>intgetdtablesize(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

       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.