.\"
.\"	aegis - project change supervisor
.\"	Copyright (C) 1993, 1994, 1998, 2002, 2005-2008 Peter Miller
.\"
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.\"	GNU General Public License for more details.
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.\"
.bp
.if t .2C
.nh 1 "The Difference Tools"
.LP
This chapter describes the difference commands in the
project configuration file.
Usually these commands are used by the
.I "aegis -DIFFerence"
command when differencing files,
but they may be used to accomplish some other things.
.LP
The default setting is for Aegis to reject filenames which contain shell
special characters.  This ensures that filenames may be substituted
into the commands without worrying about whether this is safe.  If you
set the \fIshell_safe_filenames\fP field of the project \fIaegis.conf\fP
file to \f(CWfalse\fP, you will need to surround filenames with the
\f[CW]${quote\fP \fIfilename\fP\f[CW]}\fP substitution.  This will only
quote filenames which actually need to be quoted, so users usually will
not notice.  This command applies to all of the various filenames in
the sections which follow.
.nh 2 "Binary Files"
.LP
Aegis doesn't particularly care whether your files are binary or text.
However, your difference and merge tools certainly will.
In general, you need format-specific difference and merge tools for each
of the file formats used in your project.
Unfortunately, most vendors of software which make use of proprietary file
formats do not supply difference and merge tools.
.LP
The simplest compromise is to treat all files as text, with manual
repairs for binary files.
.LP
A more elegant solution is to use a shell script invoked by the
\fIdiff_\%command\fP in the project \fIaegis.conf\fP file.
This shell script examines the file to determine the file format, and then
runs the appropriate difference tool.
Similar considerations apply to the \fImerge_\%command\fP field.
.LP
Please note that this support is not present in Aegis itself because
(a) it would cause code bloat, and (b) it is entirely possible to
do with a shell script launched by \fIdiff_command\fP.
.so c8.1.so
.so c8.2.so
.so c8.3.so