Bash parameter substitution (baparmsub?) Isnt working

Asked Aug 31 '23 at 13:41

Active Sep 02 '23 at 04:21

Viewed 79 times

I am having a problem with feeding values like _PREROUTING _POSTROUTING to strip out alphabet chars :

a=${step/\_+([a-zA-Z]/\_}
[ note: replacing underscore with \x5f does nothing for the script although using sed works via 's/_[a-zA-Z][a-zA-Z]*/_/gp' but that is NOT what i __wanted__]

(GNU)[https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html] seems to agree with me, my bash does(5.1) not have shop +patsub_replacement available for 5.2.

linux mint version and bash version see step variable and [original script in]
(Bash has problems with cmdline nft cmd vs script)

I tried [:alpha:] but neither works in script and rarely at the command line.

edited Sep 02 '23 at 04:21

asked Aug 31 '23 at 13:41

ArrowInTree

Some improvement at command line.Cite a place in the bash man page for escaping underscores? – ArrowInTree Aug 31 '23 at 15:49
I can't understand what you want to get in `a`? Just two underscores? – Alexey Ten Sep 01 '23 at 09:12
BTW, did you forget to put closing parenthesis? This `${step//_+([a-zA-Z])/_}` should work. – Alexey Ten Sep 01 '23 at 09:17
Alexey, yes two underscores mean something isn't an nft rule WITHOUT a hook or priority. See the link above. – ArrowInTree Sep 01 '23 at 10:33
Yes, in a non-interactive shell script it doesn't. Run the shell script with the "-x' option and tell me about the results. – ArrowInTree Sep 01 '23 at 10:35

Bash parameter substitution (baparmsub?) Isnt working

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