Diff: Difference between revisions

: diff -rq --exclude .svn path/to/directoryA path/to/directoryB

E.g.

diff -rq -x .svn ./work/myproject/ ./work/myproject-copy2/

=== Piping ===

The <code>diff</code> command is fast, but often the output is hard to read to find the exact difference.  You might try piping the output of the diff command to a graphical tool:

diff fileA fileB | kdiff3 -

By using the dash option to kdiff3, you're telling it to read from STDIN, so it uses the output of the former commands being piped to it.

Or, piping to <code>awk</code> to print a list of just what's in the 'left side'.

diff --suppress-common-lines --side-by-side modules.list.a.txt modules.list.b.txt |awk '{print $1}'

=== Process Substitution ===

By using process substitution, we can operate on the output of commands without the need for saving to a file.

drush pml --status=enabled --pipe > modules.list.txt

# make a bunch of changes to what modules are enabled, perhaps restoring from a backup, and compare to our original list

diff --suppress-common-lines --side-by-side <(drush pml --status=enabled --pipe) modules.list.txt

This technique comes in handy if you wish to compare two directories at their top level. The '''extensions''' directory, for example, in [[MediaWiki]] from two different installations:

diff --suppress-common-lines --side-by-side <(ls -1 /var/www/wiki.example.net/www/w/extensions/) <(ls -1 /var/www/wiki.example.org/www/w/extensions/)

=== Configuring ===

You can configure KDiff3 to ignore Version Control keywords, or do other fancy things to assist the matching portion of the KDiff execution.  This is one of the most powerful features of KDiff3

sed 's/\$\(Revision\|Author\|Log\|Header\|Date\).*\$/\$\1\$/'

Enter <pre>help:/kdiff3/preprocessors.html</pre> in Konqueror to read up on preprocessing commands

Example of diff across the network to look at repository URLs using the command-line subversion client invoking an external visual diff program instead of the built-in diff tool:

svn diff --diff-cmd kdiff3 \

http://svn.example.com/svn/myrepo/path/to/file.txt@7560 \

http://svn.example.com/svn/myrepo/path/to/file.txt@HEAD

GUI subversion clients such as kdesvn or TortoiseSVN have the same capability: built-in differencing or optional setting to invoke an external differencing tool.  For KDESvn it's 'Settings'->'Configure kdesvn'->'Diff & Merge' (screenshot provided)

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