getdtablesize(3)

1getdtablesize(3)           Library Functions Manual           getdtablesize(3)
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NAME

6       getdtablesize - get file descriptor table size
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

12       #include <unistd.h>
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14       int getdtablesize(void);
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16   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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18       getdtablesize():
19           Since glibc 2.20:
20               _DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
21           glibc 2.12 to glibc 2.19:
22               _BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
23           Before glibc 2.12:
24               _BSD_SOURCE || _XOPEN_SOURCE >= 500
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DESCRIPTION

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

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

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

38       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
39       tributes(7).
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41       ┌────────────────────────────────────────────┬───────────────┬─────────┐
42       │Interface                                   │ Attribute     │ Value   │
43       ├────────────────────────────────────────────┼───────────────┼─────────┤
44       │getdtablesize()                             │ Thread safety │ MT-Safe │
45       └────────────────────────────────────────────┴───────────────┴─────────┘
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VERSIONS

48       The glibc version of getdtablesize() calls getrlimit(2) and returns the
49       current RLIMIT_NOFILE limit, or OPEN_MAX when that fails.
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51       Portable  applications  should  employ sysconf(_SC_OPEN_MAX) instead of
52       this call.
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STANDARDS

55       None.
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HISTORY

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