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Editorial Team
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Asked: 2026-05-21T03:45:13+00:00

I’m searching for a way to replace the first occurrence of a certain text

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I’m searching for a way to replace the first occurrence of a certain text in a text file with a value ${A} and the second occurrence of the same text, on a different line, with ${B}. Can this be achieved with sed or awk or any other UNIX tool?

The toolset is fairly limited: bash, common UNIX tools like sed, grep, awk etc. Perl, Python, Ruby etc. cannot be used…

Thanks in advance for any advice
Robert

Example:

...
Text
Text
Text
Text
TEXT_TO_BE_REPLACED
Text
Text
Text
TEXT_TO_BE_REPLACED
Text
Text
Text
...

should be replaced with

...
Text
Text
Text
Text
REPLACEMENT_TEXT_A
Text
Text
Text
REPLACEMENT_TEXT_B
Text
Text
Text
...
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1 Answer

  1. Editorial Team

    Just run your script twice – once to replace the first occurrence with ${A}, once to replace the (now first) occurence with ${B}.
    To replace just one occurence:

    sed '0,/RE/s//to_that/' file

    (shamelessly stolen from How to use sed to replace only the first occurrence in a file?)

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