isatty(3) — Linux manual page

ISATTY(3)                 Linux Programmer's Manual                ISATTY(3)

NAME         top

       isatty - test whether a file descriptor refers to a terminal

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 │
       └──────────┴───────────────┴─────────┘

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.

SEE ALSO         top

       fstat(2), ttyname(3)

COLOPHON         top

       This page is part of release 5.09 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                            2019-03-06                        ISATTY(3)

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

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