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.TH ISATTY 3 2015-08-08 "Linux" "Linux Programmer's Manual"

.SH NAME

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

.SH SYNOPSIS

.nf

.B #include <unistd.h>

.PP

.BI "int isatty(int " fd );

.fi

.SH DESCRIPTION

The

.BR isatty ()

function tests whether

.I fd

is an open file descriptor referring to a terminal.

.SH RETURN VALUE

.BR isatty ()

returns 1 if

.I fd

is an open file descriptor referring to a terminal;

otherwise 0 is returned, and

.I errno

is set to indicate the error.

.SH ERRORS

.TP

.B EBADF

.I fd

is not a valid file descriptor.

.TP

.B EINVAL

.I fd

refers to a file other than a terminal.

POSIX.1 specifies the error

.BR ENOTTY

.\" FIXME . File a bug for this?

for this case.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lb lb lb

l l l.

Interface	Attribute	Value

T{

.BR isatty ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

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

.SH SEE ALSO

.BR fstat (2),

.BR ttyname (3)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I 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/.