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.\" $FreeBSD: head/lib/libc/gen/getosreldate.3 183495 2008-09-30 11:25:55Z kib $
.\"
.Dd September 30, 2008
.Dt GETOSRELDATE 3
.Os
.Sh NAME
.Nm getosreldate
.Nd get the value of
.Dv __FreeBSD_version
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn getosreldate void
.Sh DESCRIPTION
The
.Fn getosreldate
function returns an integer showing the version of the
currently running
.Fx
kernel.
Definitions of the values can be found in
.%B "The Porter's Handbook"
which is usually installed at
.Pa /usr/share/doc/en_US.ISO8859-1/books/porters-handbook/ .
.Sh RETURN VALUES
Upon successful completion,
.Fn getosreldate
returns the value requested;
otherwise the value \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ENVIRONMENT
.Bl -tag -width ".Ev OSVERSION"
.It Ev OSVERSION
If the environment variable
.Ev OSVERSION
is set, it will override the
.Fn getosreldate
return value.
.El
.Sh EXAMPLES
An example can be found in
.Pa /usr/share/examples/FreeBSD_version .
.Sh ERRORS
The
.Fn getosreldate
function may fail and set
.Va errno
for any of the errors specified for the library function
.Xr sysctl 3 .
.Sh SEE ALSO
.Rs
.%B "The Porter's Handbook"
.%O /usr/share/doc/en_US.ISO8859-1/books/porters\-handbook/
.Re
.Sh HISTORY
The
.Fn getosreldate
function appeared in
.Fx 2.0 .