Hi everyone !
I'm in need for some assistance for string manipulation with sed and regex. I tried a whole day to trial & error and look around the web to find a solution however it's way over my capabilities and maybe here are some sed/regex gurus who are willing to give me a helping hand !
With everything I gathered around the web, It seems it's rather a complicated regex and sed substitution, here we go !
What Am I trying to achieve?
I have a lot of markdown guides I want to host on a self-hosted forgejo based git markdown. However the classic markdown links are not the same as one github/forgejo...
Convert the following string:
[Some text](#Header%20Linking%20MARKDOWN.md)
Into
[Some text](#header-linking-markdown.md)
As you can see those are the following requirement:
- Pattern:
[Some text](#link%20to%20header.md) - Only edit what's between parentheses
- Replace
space (%20)with- - Everything as lowercase
- Links are sometimes in nested parentheses
- e.g. (look here
[Some text](#link%20to%20header.md))
- e.g. (look here
- Do not change a line that begins with
https(external links)
While everything is probably a bit complex as a whole the trickiest part is probably the nested parentheses :/
What I tried
The furthest I got was the following:
sed -Ei 's|\(([^\)]+)\)|\L&|g' test3.md #make everything between parentheses lowercase
sed -i '/https/ ! s/%20/-/g' test3.md #change every %20 occurrence to -
These sed/regx substitution are what I put together while roaming the web, but it has a lot a flaws and doesn't work with nested parentheses. Also this would change every %20 occurrence in the file.
The closest solution I found on stackoverflow looks similar but wasn't able to fit to my needs. Actually my lack of regex/sed understanding makes it impossible to adapt to my requirements.
I would appreciate any help even if a change of tool is needed, however I'm more into a learning processes, so a script or CLI alternative is very appreciated :) actually any help is appreciated :D !
Thanks in advance.
As I see, you've already got an answer how to convert text to lower case. So I just tell you how to replace all occurrences of
%20with-. You need to repeat substitution until no matches found. For such iteration you need to use branching to label. Below is sed script with comments.However there are some cases when this script will fail, e. g. if there is an escaped
]character in the link text. You cannot avoid such mistakes using only simple regexps, you need a full featured markdown parser for this.NB: global substitution
s///gis not applicable here because you need to perform new substitutions in a substituted text. Bothsedregexp syntaxes (basic and extended) don't support lookarounds that could solve this issue.