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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 terminal; 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).

       ┌──────────┬───────────────┬─────────┐
       │InterfaceAttributeValue   │
       ├──────────┼───────────────┼─────────┤
       │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 4.13 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/.