.TH GDIFFMK 1 "7 February 2022" "groff 1.22.4"
.SH NAME
gdiffmk \- mark differences between groff/nroff/troff files
.
.
.\" ====================================================================
.\" Legal Terms
.\" ====================================================================
.\"
.\" Copyright (C) 2004-2018 Free Software Foundation, Inc.
.\"
.\" This file is part of gdiffmk, which is part of groff, the GNU roff
.\" type-setting system.
.\"
.\" This program is free software: you can redistribute it and/or modify
.\" it under the terms of the GNU General Public License as published by
.\" the Free Software Foundation, either version 3 of the License, or
.\" (at your option) any later version.
.\"
.\" This program is distributed in the hope that it will be useful, but
.\" WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
.\" General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public License
.\" along with this program.  If not, see
.\" <http://www.gnu.org/licenses/>.
.
.
.\" ====================================================================
.SH SYNOPSIS
.\" ====================================================================
.
.SY gdiffmk
.OP \-a addmark
.OP \-c changemark
.OP \-d deletemark
.RB [ \-D
.RB [ \-B ]
.RB [ \-M
.IR "mark1 mark2" ]]
.OP \-x diffcmd
.OP \-\-
.I file1
.I file2
.RI [ output ]
.YS
.
.SY gdiffmk
.B \-\-help
.YS
.
.SY gdiffmk
.B \-\-version
.YS
.
.\" ====================================================================
.SH DESCRIPTION
.\" ====================================================================
.
.B gdiffmk
compares two
.BR groff (1),
.BR nroff (1),
or
.BR troff (1)
documents,
.I file1
and
.IR file2 ,
and creates an output which is
.I file2
with added \[lq]margin character\[rq] (.mc) commands that indicate the
differences.
.
.
.LP
If the
.I output
filename is present,
the output is written there.
.
If it is
.B \-
or absent the output is written to the standard output.
.
.
.LP
If the
.I file1
or
.I file2
argument is
.B \-
the standard input is read for that input.
.
Clearly both cannot be
.BR \- .
.
.
.LP
Note that the output is not necessarily compatible with all macro packages
and all preprocessors.
.
See section \(lqBugs\(rq below.
.
.
.\" ====================================================================
.SH OPTIONS
.\" ====================================================================
.
.TP
.BI \-a addmark
Use the
.I addmark
for source lines not in
.I file1
but present in
.IR file2 .
.
Default:
.BR + .
.
.TP
.B \-B
By default, the deleted texts marked by the
.B \-D
option end
with an added troff break command,
.BR .br ,
to ensure that the deletions are marked properly.
.
This is the only way to guarantee that deletions and small
changes get flagged.
.
This option directs the program not to insert these breaks; it makes
no sense to use it without
.BR \-D .
.
.TP
.BI \-c changemark
Use the
.I changemark
for changed source lines.
.
Default:
.BR | .
.
.TP
.BI \-d deletemark
Use the
.I deletemark
for deleted source lines.
.
Default:
.BR * .
.
.TP
.B \-D
Show the deleted portions from changed and deleted text.
.
Default delimiting marks:
.BR "[[" " \&.\|.\|.\& " "]]" .
.
.TP
.BI \-M "mark1 mark2"
Change the delimiting marks for the
.B \-D
option.
.
It makes no sense to use this option without
.BR \-D .
.
.TP
.BI \-x diffcmd
Use the
.I diffcmd
command to perform the comparison of
.I file1
and
.IR file2 .
.
In particular,
.I diffcmd
should accept the GNU
.B diff
.BI \-D name
option.
.
Default:
.BR diff (1).
.
.TP
.B \-\-
All the following arguments are treated as file names,
even if they begin with
.BR \- .
.
.TP
.B \-\-help
Print a usage message on standard error output and exit.
.
.TP
.B \-\-version
Print version information on the standard output and exit.
.
.
.\" ====================================================================
.SH BUGS
.\" ====================================================================
.
The output is not necessarily compatible with all macro packages
and all preprocessors.
.
A workaround that is often successful against preprocessor problems is
to run
.B gdiffmk
on the output of all the preprocessors instead of the input source.
.
.
.LP
.B gdiffmk
relies on the
.BI \-D name
option of GNU
.BR diff (1)
to make a merged \[lq]#ifdef\[rq] output format.
.
It hasn't been tested whether other versions of
.BR diff (1)
do support this option.
.
See also the
.BI \-x diffcmd
option.
.
.
.\" ====================================================================
.SH AUTHORS
.\" ====================================================================
.B gdiffmk
was written and is maintained by
.MT MBianchi@\:Foveal.com
Mike Bianchi
.ME .
.
.
.\" ====================================================================
.SH "SEE ALSO"
.\" ====================================================================
.
.BR groff (1),
.BR nroff (1),
.BR gtroff (1),
.BR diff (1)
.
.\" Local Variables:
.\" mode: nroff
.\" End:
.\" vim: set filetype=groff: