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Manual Reference Pages  - GETDTABLESIZE (2)

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getdtablesize - get descriptor table size

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Synopsis
Description
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#include <unistd.h>

int getdtablesize(void);

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.

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. The libc4 and libc5 versions return OPEN_MAX (set to 256 since Linux 0.98.4).

SVr4, 4.4BSD (the getdtablesize() function first appeared in 4.2BSD). It is not specified in POSIX.1-2001; portable applications should employ sysconf(_SC_OPEN_MAX) instead of this call.

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