LaTeX (and TeX, for that matter), syntax is relatively consistent, and uses a lot of backslashes.
Bourne shell syntax is somewhat inconsistent, and also uses backslashes.
Regular expression syntax I seem almost perversely disinclined to remember, and definitely sometimes often uses maybe backslashes.
Therefore, when I need to use a regular expression to work on a LaTeX document, I do it interactively in the shell until it works then paste that into a shell script. Now I need never remember or even uncover how to write that unholy combination of regex, shell, and LaTeX ever again.
For example I have defined a LaTeX macro \todo{I need more examples here.}, that draws the text “TODO: I need more examples here.” with a box around it in the document. I review outstanding sections by searching for lines on which todo items appear, using this script:
#!/bin/sh
grep -n todo\{ "$1" | sed s/\\\\todo\{\\\(.\*\\\)\}/\\1/
Now I get to blank from my mind the unholy combination of syntaces that led to 15 backslashes on one line, but still use the results.
