Breaking Bash
By Jeff Boes
January 15, 2016
Recently I managed to break the bash shell in an interesting and puzzling way. The initial symptoms were very frustrating: a workflow process we use here (creating a development camp) failed for me, but for no one else. That was at least a clue that it was me, not the workflow process.
Eventually, I narrowed down the culprit to the “grep” command (and that was more through luck than steadfast Sherlock-like detective work).
$ grep foo bar
grep: foo: No such file or directory
Eh? grep is misparsing the arguments! How does that happen?
So I began to study my bash environment. Eventually I came up with this fascinating little typo:
export GREP_OPTIONS='-color=auto'
That’s supposed to be:
export GREP_OPTIONS='--color=auto'
but it got recorded in my .bashrc as a em-dash, not a double-dash. (My guess is that I cut-and-pasted this from a web page where someone over-helpfully “typeset” this command.)
Ironically, this typo is innocuous under Bash 3.x, but when you slot it into a Bash 4.x installation, all heck busts loose.
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