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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
       referring 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.
       EINVAL fd  refers  to  a file other than a terminal.  POSIX.1 specifies
              the error ENOTTY for this case.
ATTRIBUTES
       For  an  explanation  of  the  terms  used   in   this   section,   see
       attributes(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 4.15 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                             2015-08-08                         ISATTY(3)