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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 4.16 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)