Bash parameter substitution (baparmsub?) Isnt working

ArrowInTree

8/31/24, 1:41 PM

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.

0 + 5

bash

ArrowInTree

8/31/24, 3:49 PM

Some improvement at command line.Cite a place in the bash man page for escaping underscores?

Alexey Ten

9/1/24, 9:12 AM

I can't understand what you want to get in `a`? Just two underscores?

Alexey Ten

9/1/24, 9:17 AM

BTW, did you forget to put closing parenthesis? This `${step//_+([a-zA-Z])/_}` should work.

ArrowInTree

9/1/24, 10:33 AM

Alexey, yes two underscores mean something isn't an nft rule WITHOUT a hook or priority. See the link above.

ArrowInTree

9/1/24, 10:35 AM

Yes, in a non-interactive shell script it doesn't. Run the shell script with the "-x' option and tell me about the results.

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