isfdtype - test file type of a file descriptor

       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).

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

       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).

       Standard C library (libc, -lc)

       isfdtype - test file type of a file descriptor

       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.

fstat(2)

Linux man-pages 6.9.1                              2024-05-02                                        isfdtype(3)

       None.

#include<sys/stat.h>#include<sys/socket.h>intisfdtype(intfd,intfdtype);

   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

       Portable applications should use fstat(2) instead.