#ifdef linux

What changed? Sometimes, when using VCS systems such as bazaar, there is a tendency to forget to perform the necessary 'book-keeping' for those not using it because you get so focused on the tooling itself. Most VCS systems expect the author to provide a brief explanatory message per commit. This log is invaluable since it (hopefully!) provides insightful context into the programmers intentions. However, that meta-data is only available to those with a copy of the branch/checkout/stream/view or whatever your VCS calls it. But what about those who only come into contact with the project via release tarballs for example? I'm thinking specifically of changelogs. Debian and Ubuntu provide the incredibly useful ' dch ' (aka debchange ) tool which synchronises the VCS commit message with the latest ' debian/changelog ' file entry. But what if you're not working on a Debian project? When you're working on a fast-paced project, or just working at a...

Occasionally, after committing some changes on a bzr branch, I'll come back to it and want to make further changes. So, I'll have done something like this: $ bzr commit $ # Oops! Forgot to update foo.c. Let's do that now... $ vim src/foo.c $ bzr status modified: src/foo.c But rather than creating a second commit for the newest changes, I'll want to combine those new changes and the changes in the latest commit into a single new commit. How do we do this? With bzr its easy: $ bzr log -l1 > /tmp/commit.log # save the latest commit log entry $ bzr shelve --all -m "latest changes" # save the latest uncommitted changes $ bzr uncommit --dry-run # check its going to work $ bzr uncommit # undo the last commit $ bzr unshelve --dry-run # check if its going to work $ bzr unshelve # apply the latest changes to the working directory $ bzr commit ...

This is a useful trick to avoid creating lots of intermediate temporary files when you're trying to compare two files that are almost the same, but which have some fields which are guaranteed to be different. Classic examples of this are two log files that have almost the same data in them, but where every line in these files is prefixed by a pesky timestamp which is different between the two files. bash process substitution (using named pipes) to the rescue! Let's assume we have two files " file1.log " and " file2.log " and the first six space-separated fields comprise a timestamp. To ignore those fields and just diff the log file contents we can do this: $ diff <(cut -d" " -f7- /tmp/file1.log) <(cut -d" " -f7- /tmp/file2.log) But why limit yourself to a textual diff. Go graphical if you prefer: $ meld <(cut -d" " -f7- /tmp/file1.log) <(cut -d" " -f7- /tmp/file2.log) This technique can be employed ...