isfdtype(3) Library Functions Manual isfdtype(3)
NAME
isfdtype - test file type of a file descriptor
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <sys/stat.h>
#include <sys/socket.h>
int isfdtype(int fd, int fdtype);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
isfdtype():
Since glibc 2.20:
_DEFAULT_SOURCE
Before glibc 2.20:
_BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
The isfdtype() function tests whether the file descriptor fd refers to
a file of type fdtype. The fdtype argument specifies one of the S_IF*
constants defined in <sys/stat.h> and documented in stat(2) (e.g.,
S_IFREG).
RETURN VALUE
The isfdtype() function returns 1 if the file descriptor fd is of type
fdtype and 0 if it is not. On failure, -1 is returned and errno is set
to indicate the error.
ERRORS
The isfdtype() function can fail with any of the same errors as fs-
tat(2).
VERSIONS
Portable applications should use fstat(2) instead.
STANDARDS
None.
HISTORY
It appeared in the draft POSIX.1g standard. It is present on OpenBSD
and Tru64 UNIX (where the required header file in both cases is just
<sys/stat.h>, as shown in the POSIX.1g draft).
SEE ALSO
fstat(2)
Linux man-pages 6.7 2023-10-31 isfdtype(3)
Generated by dwww version 1.16 on Tue Dec 16 17:24:02 CET 2025.