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.Dd October 27, 2002
.Dt CHECK_UTILITY_COMPAT 3
.Os
.Sh NAME
.Nm check_utility_compat
.Nd "determine whether a utility should be compatible"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn check_utility_compat "const char *utility"
.Sh DESCRIPTION
The
.Fn check_utility_compat
function checks whether
.Fa utility
should behave in a traditional
.Pq Fx 4.7 Ns -compatible
manner, or in accordance with
.St -p1003.1-2001 .
The configuration is given as a comma-separated list of utility names;
if the list is present but empty, all supported utilities assume their
most compatible mode.
The
.Fn check_utility_compat
function first checks for an environment variable named
.Ev _COMPAT_FreeBSD_4 .
If that environment variable does not exist, then
.Fn check_utility_compat
will attempt to read the contents of a symbolic link named
.Pa /etc/compat-FreeBSD-4-util .
If no configuration is found, compatibility mode is disabled.
.Sh RETURN VALUES
The
.Fn check_utility_compat
function returns zero if
.Fa utility
should implement strict
.St -p1003.1-2001
behavior, and nonzero otherwise.
.Sh FILES
.Bl -tag -width ".Pa /etc/compat-FreeBSD-4-util"
.It Pa /etc/compat-FreeBSD-4-util
If present, a symbolic link whose expansion gives system-wide default settings
for the
.Fn check_utility_compat
function.
.El
.Sh ERRORS
No errors are detected.
.Sh HISTORY
The
.Fn check_utility_compat
function first appeared in
.Fx 5.0 .
.Sh AUTHORS
This manual page was written by
.An Garrett Wollman Aq Mt wollman@FreeBSD.org .