.\" (C) Copyright 2016 Craig Small <csmall@enc.com.au>
.\"
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.TH PROCPS_LINUX_VERSION 3 2016-05-01 "libproc-2"
.\" Please adjust this date whenever revising the manpage.
.\"
.SH NAME
procps_linux_version \-
provide current version of Linux as an integer
.SH SYNOPSIS
.B #include <proc/procps.h>
.sp
.B int procps_linux_version(void);
.sp
Link with \fI\-lprocps\fP.
.SH DESCRIPTION
The function
.BR procps_linux_version ()
returns the current Linux version as an integer. On non-Linux systems that
have an emulated proc filesystem this function returns the version of the
Linux emulation instead.
The Linux version consists of a triple of positive integers representing
the major, minor and patch versions of the kernel.
.PP
The library provides 3 macros for separating out the components.
.RS 4
.TP 1.2i
.BR LINUX_VERSION_MAJOR (ver)
Extract the major component from the given version integer.
.TP
.BR LINUX_VERSION_MINOR (ver)
Extract the minor component from the given version integer.
.TP
.BR LINUX_VERSION_PATCH (ver)
Extract the patch component from the given version integer.
.RE
.PP
To encode a given Linux version, such as using it to compare against the current
version, use the following macro:
.TP
.BI LINUX_VERSION( major , minor , patch )

.SH RETURN VALUE
The
.BR procps_linux_version ()
returns a positive integer encoding the Linux version if successful. Otherwise
returns a negative integer to one of the values defined below.
.TP
.B -EIO
The procps library was unable to read the osrelease file.
.TP
.B -ERANGE
Unable to parse the osrelease file.
.PP
.BR procps_linux_version ()
may also return any (negated) value that \fBfopen\fR() may set errno to.

.SH FILES
.TP
.I /proc/sys/kernel/osrelease
Contains the release version of the Linux kernel or proc filesystem.

.SH VERSIONS
.B procps_linux_version()
first appeared in libproc-2 version 0.0.

.SH BUGS
Due to the way the three numbers are encoded into a single integer,
.BR procps_linux_version ()
and the associated macros assume 255 for the maximum value for the
minor and patch level and 32767 (hex 0x7fff) for the maximum value
for the major version. In other words, when Linux v 32768.0.0 comes
out, this function will break.
.\" Maj/6yr - In 7452 we'll think of something

.SH SEE ALSO
.BR fopen (3),
.BR proc (5).