Determining which custom files need to be merged when performing Movable Type upgradesEdit

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Movable Type’s upgrade procedure effectively amounts to a performing a full reinstallation. This wouldn’t be much of a problem if it weren’t for the fact that custom files and modifications in an existing installation must be painstakingly identified and copied over into the new version prior to re-uploading the 1,100+ files that make up Movable Type (using find . -type f | wc -l from the top level of the Movable Type 3.35 archive counts 1,158 distinct files).

These tips describe the basic procedure for performing the merge. Here we assume that the old version was installed in mt. Version 3.34 is used in this example:

  • On the local host, rename the old mt folder to mt-3.34
  • Move the newly extracted files into position, naming the folder mt
  • Use diff to examine the differences between the trees:
diff mt-3.34 mt
diff -r mt-3.34 mt | less
diff -r mt-3.34 mt | grep "Only in"

When you see lines like Only in mt-old: mt-config.cgi, this is most likely an indication of a file that should be copied over to the new directory.

In my case, there were 4 files that needed to be copied for the 3.34 to 3.35 upgrade:

cp mt-3.34/.htaccess mt/
cp mt-3.34/mt-config.cgi mt/
cp mt-3.34/plugins/Markdown.pl mt/plugins/
cp mt-3.34/plugins/wikitext.pl mt/plugins/

In the case of the 3.35 to 4.0.1 upgrade the files I copied over were:

.htaccess
mt-config.cgi
plugins/wikitext.pl

I could then double-check the result as using:

diff -r mt-3.34 mt | grep "Only in"

Useful data-mining commands

Numbers shown are for the example upgrade from 3.34 to 3.35.

Total number of lines in the diff

diff -r mt-3.34 mt | wc -l # 3512

This line count reflects changed lines, removed lines, modified lines, and of course custom files not present in the vanilla Movable Type distribution, such as the Markdown.pl and wikitext.pl plugins mentioned above.

Total number of substantive lines

This line count excludes metadata and counts only lines showing the actual changes:

diff -r mt-3.34 mt | grep '^[><]' | wc -l # 2063

Many of the changed lines just contain RCS tags, which can be excluded from the count as follows:

diff -r mt-3.34 mt | grep '^[><]' | grep -v '\$Id' | wc - l # 1815

See also

For an example of using this procedure in the context of an upgrade, see "Upgrading from Movable Type version 3.34 to 3.35".