isatty

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

NAME
       isatty - test whether a file descriptor refers to a terminal

SYNOPSIS
       #include <unistd.h>

       int isatty(int fd);

DESCRIPTION
       The  isatty()  function tests whether fd is an open file descriptor re-
       ferring to a terminal.

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

ERRORS
       EBADF  fd is not a valid file descriptor.

       ENOTTY fd  refers  to a file other than a terminal.  On some older ker-
              nels, some types of files resulted in the error EINVAL  in  this
              case  (which  is a violation of POSIX, which specifies the error
              ENOTTY).

ATTRIBUTES
       For an  explanation  of  the  terms  used  in  this  section,  see  at-
       tributes(7).

       +----------+---------------+---------+
       |Interface | Attribute     | Value   |
       +----------+---------------+---------+
       |isatty()  | Thread safety | MT-Safe |
       +----------+---------------+---------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.

SEE ALSO
       fstat(2), ttyname(3)

COLOPHON
       This  page  is  part of release 5.05 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)