Regex syntax and features vary between implementations. \d isn’t supported by BRE/ERE flavors.

GNU grep supports PCRE, so you can use grep -oP '/dev/loop\d' or grep -o '/dev/loop[0-9]' if you are matching only one digit character.

Thanks a lot for the feedback :)

Well, I’m not going to even try understanding the various features used in that sed command. I do know how to use basic loops with labels, but I never bothered with all the buffer manipulation stuff. I’d rather use awk/perl/python for those cases.

This might work, but I think it is best to not tinker further if you already have a working script (especially one that you understand and can modify further if needed).

perl -pe 's/\[[^]]+\]\((?!https?)[^#]*#\K[^)]+(?=\))/lc $&=~s:%20|\d\K\.(?=\d):-:gr/ge'

Hmm, OP mentioned “Only edit what’s between parentheses” - don’t see anywhere that whole URL shouldn’t be changed…

Here’s a solution with perl (assuming you don’t want to change http/https after the start of ( instead of start of a line):

perl -pe 's/\[[^]]+\]\(\K(?!https?)[^)]+(?=\))/lc $&=~s|%20|-|gr/ge' ip.txt

• e flag allows you to use Perl code in the substitution portion.
• \[[^]]+\]\(\K match square brackets and use \K to mark the start of matching portion (text before that won’t be part of $&)
• (?!https?) don’t match if http or https is found
• [^)]+(?=\)) match non ) characters and assert that ) is present after those characters
• $&=~s|%20|-|gr change %20 to - for the matching portion found, the r flag is used to return the modified string instead of change $& itself
• lc is a function to change text to lowercase

GNU datamash (https://www.gnu.org/software/datamash/alternatives/) - handy tool for data munching. There’s also https://github.com/BurntSushi/xsv

Check out my chapter on GNU grep BRE/ERE for those wanting to learn this regex flavor: https://learnbyexample.github.io/learn_gnugrep_ripgrep/breere-regular-expressions.html (there’s also another chapter for PCRE)

I use Vim ;)

Python itself provides IDLE, which is good enough for beginners. https://thonny.org/ is another good one for beginners.

As mentioned by others, Jetbrains is good for many languages. https://www.kdevelop.org/ is another option.

I have a list of learning resources for CLI tools and scripting here: https://learnbyexample.github.io/curated_resources/linux_cli_scripting.html

I’ve also written a few TUI interactive apps to practice text processing commands like grep, sed, awk, coreutils, etc: https://github.com/learnbyexample/TUI-apps

oxipng, pngquant and svgcleaner for optimizing images

auto-editor for removing silent portions from video recordings

Not my blog, just sharing it here. Saw it on HN (https://news.ycombinator.com/item?id=40419325)

Yeah, it is uncommon spelling, but if you google, you’ll find it’s not that rare ;)

I had to learn Linux CLI tools, Vim and Perl at my very first job. Have a soft spot for Perl, despite not using it much these days other than occasional one-liners (mainly for advanced regex features).

Thanks! 😊

That’s great to hear and thanks for the kind feedback :)

I’ve written books on regex too, if you are interested in learning ;)

See also:

• tldr — collection of community-maintained help pages for command-line tools
• explainshell — write down a command-line to see the help text that matches each argument
• General purpose command-line tools — examples for most common usecases
• Bash reference cheatsheet — nicely formatted and explained well
• Bash scripting cheatsheet — quick reference to getting started with Bash scripting

Inspired by explainshell, I wrote a script (https://github.com/learnbyexample/command_help) to be used from the terminal itself. It is a bit buggy, but works well most of the time. For example:

$ ch grep -Ao
       grep - print lines that match patterns

       -A NUM, --after-context=NUM
              Print NUM lines of trailing context after matching lines.  Places a
              line containing a group separator (--) between contiguous groups of
              matches.  With the -o or --only-matching option, this has no effect
              and a warning is given.

       -o, --only-matching
              Print  only  the matched (non-empty) parts of a matching line, with
              each such part on a separate output line.