CODEWITHSUNDEEP
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Ed Jones
Ed Jones

Reputation: 104

sed to remove section of text from a variable

So I think I've cracked the regex but just can't crack how to get sed to make the changes. I have a variable which is this:

MAKEVAR = EPICS_BASE=$CI_PROJECT_DIR/3.16/base IPAC=$CI_PROJECT_DIR/3.16/support/ipac SNCSEQ=$CI_PROJECT_DIR/3.16/support/seq

(All one line). But I want to delete the particular section defining IPAC so my regex looks like this:

(IPAC.+\s)

I know from using this tool that that should be correct:

https://www.regextester.com/98103

However when I run different iterations of trying out sed like:

sed 's/(IPAC.+\s)/\&/g' <<< "$MAKEVAR"

And then echo out MAKEVAR, the IPAC section still exists.

How can I update a particular section of text in a shell variable to remove a section beginning with IPAC up until the next space?

Thanks in advance

Upvotes: 0

Views: 377

Answers (3)

Ryszard Czech
Ryszard Czech

Reputation: 18611

Use a shorter

MAKEVAR=$(sed 's/IPAC.*ipac//' <<< "$MAKEVAR")

IPAC.*ipac matches all the way from first IPAC to last ipac. The matched text is removed from the text.

Upvotes: 0

Ed Morton
Ed Morton

Reputation: 203645

regextester (or any other online tool) is a great way to verify that a regexp works in that online tool. Unfortunately that doesn't mean it'll work in any given command-line tool. In particular your regexp includes \s which is specific to PCREs and some GNU tools, and uses (...) to delineate capture groups but that's only used in EREs and PCREs, not BREs such as sed supports by default where you'd have to use \(...\), and your replacement text is using '&' which is telling sed you want to replace the string that matches the regexp with a literal \& when in fact you just want to remove it.

This is how to do what I think you're trying to do using any sed:

$ sed 's/IPAC[^ ]* //' <<< "$MAKEVAR"
EPICS_BASE=$CI_PROJECT_DIR/3.16/base SNCSEQ=$CI_PROJECT_DIR/3.16/support/seq

Upvotes: 1

Ed Jones
Ed Jones

Reputation: 104

Nevermind, found a workaround: MAKEVAR=$(sed -E 's/(IPAC.+ipac)//' <<<"$MAKEVAR")

Upvotes: 0

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