.\"	$OpenBSD: mlinks.1,v 1.4 2017/07/07 23:55:21 bluhm Exp $
.\"
.\" Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: July 7 2017 $
.Dt MLINKS 1
.Os
.Sh NAME
.Nm mlinks
.Nd extract desired mlinks from a mandoc.db(5) file
.Sh SYNOPSIS
.Nm mlinks
.Ar file
.Sh DESCRIPTION
The
.Nm
utility reads a
.Xr mandoc_db 5
database from the given
.Ar file .
For each manual page name that does not agree with the filename,
it writes one line to the standard output, containing:
.Pp
.Bl -dash -compact
.It
the filename
.It
a comma
.It
the other name
.It
a period
.It
the section number
.El
.Pp
This format is useful for portable software intended to run on
operating systems that require multiple file system entries
for pages having multiple names.
.Pp
For example, it is used to generate MLINKS for portable LibreSSL.
.Sh FILES
The header files
.Qq Pa dbm_map.h
and
.Qq Pa dbm.h
and the object files
.Pa dbm_map.o
and
.Pa dbm.o
from the
.Xr mandoc 1
build are required to compile and link
.Nm .
.Sh EXIT STATUS
.Ex -std
It fails when no argument or more than one argument is given, when
.Fn dbm_open
fails, or when database corruption is detected.
.Sh EXAMPLES
Typical usage looks like this:
.Bd -literal -offset indent
cd /usr/src/usr.bin/mandoc/
make obj
make
cd /usr/src/regress/usr.bin/mandoc/db/mlinks/
make obj
make
makewhatis -a /usr/src/lib/libssl/man
\&./obj/mlinks /usr/src/lib/libssl/man/mandoc.db > ssl.mlinks
.Ed
.Sh AUTHORS
.An Ingo Schwarze Aq Mt schwarze@openbsd.org
.Sh CAVEATS
The
.Nm
utility only partially validates the database format.
For complete validation, use the
.Xr dbm_dump 1
utility found in
.Pa /usr/src/regress/usr.bin/mandoc/db/dbm_dump/ .