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Tab Completion for CDPATH on Mac

Though I’ve written several shell-related posts, I’m not a shell geek. Let’s get that out of the way right now. The shell is a tool for me and nothing more. I had used tcsh for years and years and years for no other reason than someone told me it was better than bash when I first started doing any “real” Unix work. I recently moved to bash because, frankly, I was tired of having to custom-configure every system I login to on a regular basis. Bash is the default shell for most Unix flavors and since the shell is only a tool, I saw no reason to continue spending time on customizations.

The other day when @patrick_mc dropped a link to a bash mastery article in a tweet, I saw the opportunity to learn something. Though it was hardly a masterful type article, I did learn about one thing that I didn’t know about before: CDPATH.

The details of CDPATH are outside of the scope of this post, but the gist is that it works the way that the PATH works. Type a directory and if it’s in your CDPATH, the OS will find it and change to that directory by name alone – even if the directory name isn’t in your current working directory. For example, if I’m in my home directory, I can type www and be delivered directly to /Users/me/Development/www as long as /Users/me/Development is in my CDPATH.

When I first read the article, I was at work and on my Ubuntu machine so I tried it there first by adding the following line to my /home/me/.bash_profile:

export CDPATH=.:~:~/Development

After sourcing ($ source .profile) my updated profile, I was able to jump to directories exactly as advertised. Moreover, tab completion worked brilliantly so, from my home directory, I could type cd w[TAB] and it would complete to cd www. Brilliant.

It wasn’t quite so easy on the Mac, though. I updated my .profile, but couldn’t get it to work. I thought I had a syntax error in my .profile, but after hours of trial and error, I was no closer. I pinged the #lazyweb on Twitter to ask whether it worked for others on OS X and got more than a few affirmative responses which just confused me even more. A quick chat with Brad Greenlee, though, pointed out the error of my ways. It turned out that CDPATH was working great, but I was assuming (yeah, I know) that tab completion would also work. It didn’t.

For me, something like CDPATH is only useful with tab completion because otherwise, I can tab complete the full path to the file before I can type the entire directory name (for all but the shortest directory names). Besides, the Tab key is completely woven into the fabric of my muscle memory now. I can’t give it up when I’m in the shell. After a little digging, I found the answer:

$ sudo port install bash-completion

Yep, that’s it (assuming you have MacPorts installed). Well, almost. You do have to update your .profile (or .bash_profile, .bashrc, etc.) to source the installed file at /opt/local/etc/bash_completion. Instructions for doing so are printed in the output of the installation. In case you close your window too early, though:

if [ -f /opt/local/etc/bash_completion ]; then
    . /opt/local/etc/bash_completion

Happy completing.

Migrating from tcsh to bash

My move to Linux in the workplace almost necessarily entails a shell change. I’ve been using tcsh for years, going back to the days before bash added tab completion, if memory serves, but in the last year or so, I’ve been considering a switch to bash for several reasons:

  1. It’s the default shell on the Mac and most CLI help articles reference bash.
  2. Every Unix variant I can think of seems to ship with bash as the default shell.
  3. Some Unix variants don’t even bother to ship with tcsh.

Ubuntu, my distro of choice, is one of those variants that doesn’t ship with tcsh. Yeah, I know I can install tcsh easily enough, but that seems like a recipe for repetition over time as I work on new machines running other distros that may or may not include a tcsh install. For the sake of universal access, I think I’d rather just conform.

This past weekend I began the process of migrating my well-worn, painstakingly accumulated .tcshrc login script to its bash counterpart, .bash_profile. What I’m finding is that it’s not all that simple.

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