isatty(3) — Linux manual page

 isatty(3)                Library Functions Manual               isatty(3) 

NAME         top

        isatty - test whether a file descriptor refers to a terminal 

LIBRARY         top

        Standard C library (libc, -lc) 

SYNOPSIS         top

        #include <unistd.h>         int isatty(int fd); 

DESCRIPTION         top

        The isatty() function tests whether fd is an open file descriptor        referring to a terminal. 

RETURN VALUE         top

        isatty() returns 1 if fd is an open file descriptor referring to a        terminal; otherwise 0 is returned, and errno is set to indicate        the error. 

ERRORS         top

        EBADF  fd is not a valid file descriptor.         ENOTTY fd refers to a file other than a terminal.  On some older               kernels, some types of files resulted in the error EINVAL               in this case (which is a violation of POSIX, which               specifies the error ENOTTY). 

ATTRIBUTES         top

        For an explanation of the terms used in this section, see        attributes(7).        ┌──────────────────────────────────────┬───────────────┬─────────┐        │ Interface                            │ Attribute     │ Value   │        ├──────────────────────────────────────┼───────────────┼─────────┤        │ isatty()                             │ Thread safety │ MT-Safe │        └──────────────────────────────────────┴───────────────┴─────────┘ 

STANDARDS         top

        POSIX.1-2008. 

HISTORY         top

        POSIX.1-2001, SVr4, 4.3BSD. 

SEE ALSO         top

        fstat(2), ttyname(3) 

COLOPHON         top

        This page is part of the man-pages (Linux kernel and C library        user-space interface documentation) project.  Information about        the project can be found at         ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report        for this manual page, see        ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.        This page was obtained from the tarball man-pages-6.10.tar.gz        fetched from        ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on        2025-02-02.  If you discover any rendering problems in this HTML        version of the page, or you believe there is a better or more up-        to-date source for the page, or you have corrections or        improvements to the information in this COLOPHON (which is not        part of the original manual page), send a mail to        [email protected]  Linux man-pages 6.10            2024-07-23                      isatty(3) 

Pages that refer to this page: bash(1),  ttyname(3)

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