Csh Stupidity

One of the great things about the Linux era, is that bash seems to be taking over as the preferred shell to use, instead of csh/tcsh. The projects at my current job began during the SunOS era, so when I started there a couple years ago I went with the flow and let the sysadmin set up my default as tcsh just like everyone else there uses. When I was getting started, no one had a reasonable .profile or .bashrc I could use, so I went with tcsh so I could use the tribal .cshrc.

In terminals, the first command I run is "bash"; most of my work is in an emacs shell window, so my .emacs says (setq shell-file-name "/bin/bash") -- actually there's an (if) in there to choose cygwin's bash if I happen to be on Windows. I do a lot of shell programming at the command line, and I simply can't live with csh-style programming.

A few days ago I was working on my .cshrc file, and I noticed how dim-witted csh's if-else handling is. The classic anti-csh diatribe is Csh Programming Considered Harmful, which is an entertaining read, but there's some insanity that isn't even covered in that worthy rant. Let me start by presenting a correct csh script:

setenv FOO hello
if ($FOO == hello) then
echo hi
else if ($FOO == goodbye) then
echo see ya
endif

Source that script, and the output is:

hi

Various typos can have effects on this script that range from annoying to silent but deadly. Here's an annoying one: put the second if on a different line from the else. The output is:

hi
else: endif not found.

Well, at least you got an error message telling you something is up, although requiring two keywords to be on the same line is a level of stupidity worthy of Tcl. What if you do the opposite, and have too many endifs? Well, the output is just "hi", with no error message. I suppose that doesn't bite too much, until later when you nest another if into the script, and it suddenly gets closed by one of your stealth extra endifs.

But here's a bad one. Take the original script. Add an else at the beginning, and an endif at the end. Seems like an else without an accompanying if should get a syntax error, but it doesn't. The extra endif -- which might have been there because we always had an extra one, but never got an error about it -- closes the weird else. And guess what? The script runs with no errors, and no output. The else is kind of a "if not true". How can this be a good thing? 

[Update 2013/11/21: Ha! Now this has actually happened to me, in almost the same way described here.  I had to add some functionality to an existing script at work.  It was a branch added near the top of an if with several branches. I mistakenly added an endif at the end of my new branch. The new functionality (and the branch above it) tested fine, no error reported, so I checked it in. A few days later someone noticed that the later branches weren't running (this script gets launched from a cron job, so the problem wasn't something that would get immediately noticed). The later branches -- starting with an else for which there was no active if -- were silently skipped. Grrrr...]

I did these experiments with csh and tcsh on RedHat. Avoid csh. Long live bash!