Replace a substring but not the entire string [duplicate]

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Replace Strings Using Sed And Regex (6 answers)

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I have a YAML file, schema.yml, with some values like:

{{CODE}}-project
{{CODE}}-project-start

If I use

REP="s/{{CODE}}-project/123-project"
cat schema.yml | sed "$REP"

it will replace both {{CODE}}-project and {{CODE}}-project-start. How can I replace only {{CODE}}-project occurrences but not {{CODE}}-project-start occurrences?

@tink Did you look at the answers there? They use \< and \>, but this will match before - so it won't solve this problem. — Barmar
– Barmar, Commented Sep 13, 2023 at 20:21

dawg · Accepted Answer · 2023-09-13 20:44:13Z

0

Use anchors:

sed 's/^{{CODE}}-project$/123-project/' file

Or skip the substitution if something else is matched on the line; in this case -start:

sed '/-start/! s/^{{CODE}}-project/123-project/' file

Or Perl with a negative lookahead:

perl -lpe 's/^{{CODE}}-project(?!-start)/123-project/' file

All print:

123-project
{{CODE}}-project-start

Btw: using cat is not necessary to feed input into sed. Better to read the file directly.

edited Sep 13, 2023 at 20:44

answered Sep 13, 2023 at 20:34

dawg

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