Suppose that you have an Ubuntu 8.04 system where you have opted to make/bin/sh be bash, the way it used to be in 6.06, and you have an accountwith /bin/sh as the login shell (for example, you created it with plain useradd ). So you log in to the account and everything seems normal andbash-y, until you try to do filename completion and get:

$ cd / -sh: <( compgen -d -

When I ran into the issue of the re module not exposing its types , I considered several solutions to my underlyingproblem of distinguishing strings from compiled regular expressions.For various reasons, I wound up picking the solution that was the leastannoying to code; I decided whether something was compiled regularexpression by checking to see if it had a .match attribute.

This is the traditional Python approach to the problem; don't checktypes as such, just check to see if the object has the behavior thatyou'

Here is a note to myself about shell scripting, especially things that Iwrite on the fly on the command line: under no circumstance should I useany ' for ... ' loop index variable apart from $i .

I say this because, based on experimental evidence so far, I amcompletely sure to use $i in the body of the for loop, no matterwhat sensible variable name I picked as the loop index in the for statement. And, of course, the Bourne shell will let me