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Tips for golfing in Bash

What general tips do you have for golfing in Bash? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Bash (e.g. "remove comments" is not an answer). Please post one tip per answer.

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\$\begingroup\$ Sometimes $( ) is needed if you have nested command substitutions; otherwise you'd have to escape the inner `` \$\endgroup\$

Digital Trauma
– Digital Trauma

2014年04月13日 04:18:10 +00:00
Commented Apr 13, 2014 at 4:18
1

\$\begingroup\$ These technically do different things, I've had to use the backticks instead of $() when I wanted to run the substitution on my machine instead of the scp target machine, for example. In most cases they're identical. \$\endgroup\$

undergroundmonorail
– undergroundmonorail

2014年04月21日 19:31:35 +00:00
Commented Apr 21, 2014 at 19:31
4

\$\begingroup\$ @undergroundmonorail: you never need backticks. Anything they can do, $() can do if you quote things properly. (unless you need your command to survive something that munges $ but not backticks). There are some subtle differences in quoting things inside them. mywiki.wooledge.org/BashFAQ/082 explains some differences. Unless you're golfing, never use backticks. \$\endgroup\$

Peter Cordes
– Peter Cordes

2015年09月24日 07:09:47 +00:00
Commented Sep 24, 2015 at 7:09
\$\begingroup\$ @PeterCordes I'm sure there was a way but everything I tried at the time didn't work. Even if backticks weren't the best solution, I was glad I knew about them because it was the only solution I had. ¯\_(ツ)_/¯ \$\endgroup\$

undergroundmonorail
– undergroundmonorail

2015年09月24日 07:43:59 +00:00
Commented Sep 24, 2015 at 7:43
\$\begingroup\$ @DigitalTrauma Sample of nesting: echo `bc <<<"\`date +%s\`-12"` ... (It's hard to post sample containing backtick in comment, there! ;) \$\endgroup\$

F. Hauri - Give Up GitHub
– F. Hauri - Give Up GitHub

2017年01月24日 17:22:46 +00:00
Commented Jan 24, 2017 at 17:22

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