CODEWITHSUNDEEP
regexsed
Unitech
Unitech

Reputation: 5991

Replace only the first occurence matching a regex with sed

I have a string 

test:growTest:ret

And with sed i would to delete only test: to get :

growTest:ret

I tried with

sed '0,/RE/s/^.*://'

But it only gives me

ret

Any ideas ?

Thanks

Upvotes: 4

Views: 11944

Answers (3)

ulidtko
ulidtko

Reputation: 15644

Modify your regexp ^.*: to ^[^:]*:

All you need is that the .* construction won't consume your delimiter — the colon. To do this, replace matching-any-char . with negated brackets: [^abc], that match any char except specified.

Also, don't confuse the two circumflexes ^, as they have different meanings: first one matches beginning of string, second one means negated brackets.

Upvotes: 7

Yantao Xie
Yantao Xie

Reputation: 12916

  1. Sed use hungry match. So ^.*: will match test:growTest: other than test:.
  2. Default, sed only replace the first matched pattern. So you need not do anything specially.

Upvotes: 1

Olhovsky
Olhovsky

Reputation: 5559

If I understand your question, you want strings like test:growTest:ret to become growTest:ret.

You can use:

sed -i 's/test:(.*$)/\1/'

i means edit in place.

s/one/two/ replaces occurences of one with two.

So this replaces "test:(.*$)" with "\1". Where \1 is the contents of the first group, which is what the regex matched inside the braces.

"test:(.*$)" matches the first occurence of "test:" and then puts everything else until the end of the line unto the braces. The contents of the braces remain after the sed command.

Upvotes: 1

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