isfdtype(3) — Linux manual page

isfdtype(3)              Library Functions Manual             isfdtype(3)

NAME         top

       isfdtype - test file type of a file descriptor

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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         top

       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         top

       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         top

       The isfdtype() function can fail with any of the same errors as
       fstat(2).

VERSIONS         top

       Portable applications should use fstat(2) instead.

STANDARDS         top

       None.

HISTORY         top

       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         top

       fstat(2)

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                    isfdtype(3)

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