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| .TH ISFDTYPE 3 2021-03-22 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| isfdtype \- test file type of a file descriptor |
| .SH SYNOPSIS |
| .nf |
| .B #include <sys/stat.h> |
| .B #include <sys/socket.h> |
| .PP |
| .BI "int isfdtype(int " fd ", int " fdtype ); |
| .fi |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR isfdtype (): |
| .nf |
| Since glibc 2.20: |
| _DEFAULT_SOURCE |
| Before glibc 2.20: |
| _BSD_SOURCE || _SVID_SOURCE |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR isfdtype () |
| function tests whether the file descriptor |
| .I fd |
| refers to a file of type |
| .IR fdtype . |
| The |
| .I fdtype |
| argument specifies one of the |
| .B S_IF* |
| constants defined in |
| .I <sys/stat.h> |
| and documented in |
| .BR stat (2) |
| (e.g., |
| .BR S_IFREG ). |
| .SH RETURN VALUE |
| The |
| .BR isfdtype () |
| function returns 1 if the file descriptor |
| .I fd |
| is of type |
| .IR fdtype |
| and 0 if it is not. |
| On failure, \-1 is returned and |
| .I errno |
| is set to indicate the error. |
| .SH ERRORS |
| The |
| .BR isfdtype () |
| function can fail with any of the same errors as |
| .BR fstat (2). |
| .SH CONFORMING TO |
| The |
| .BR isfdtype () |
| function is not specified in any standard, |
| but did appear in the draft POSIX.1g standard. |
| It is present on OpenBSD and Tru64 UNIX |
| (where the required header file in both cases is just |
| .IR <sys/stat.h> , |
| as shown in the POSIX.1g draft), |
| and possibly other systems. |
| .SH NOTES |
| Portable applications should use |
| .BR fstat (2) |
| instead. |
| .SH SEE ALSO |
| .BR fstat (2) |