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I have a very large colon-delimited file with two columns:

dhsj fdksjdk:dndkdlkfkd
shfdosod dkjsosjd:dkj dosjeod
dhswisoaidodisbw: dhsoi wjdos
fjfdododjfideefkjso sn:fhfdkd dkdjdf

If the first column contains a space, I need to remove it (i.e. collapse text together):

dhsjfdksjdk:dndkdlkfkd
shfdosoddkjsosjd:dkj dosjeod
dhswisoaidodisbw: dhsoi wjdos
fjfdododjfideefkjsosn:fhfdkd dkdjdf

In other words, everything to the left of the colon needs to be stripped of spaces, and everything to the right of the colon needs to remain untouched.

I know how to use cut -d ":" f1 to pull the first column and tr -d '[[:blank:]]' to filter out space or tab characters, but then I would have to place that column back into the file and this seems like a roundabout way of doing things.

What's the most efficient way to do what I want here?

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  • Can you post sample input file and the desired output? – Arkadiusz Drabczyk Dec 5 '20 at 19:18
  • @ArkadiuszDrabczyk Added. – Hashim Aziz Dec 5 '20 at 19:31
4

Like that:

$ awk -F: '{gsub(/ /, "", $1); print $1 FS $2}' FILE
dhsjfdksjdk:dndkdlkfkd
shfdosoddkjsosjd:dkj dosjeod
dhswisoaidodisbw: dhsoi wjdos
fjfdododjfideefkjsosn:fhfdkd dkdjdf
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  • 1
    Perfect, thank you. I'm always amazed at how powerful awk is, I should learn it one day. – Hashim Aziz Dec 5 '20 at 20:00
  • Quick clarification, does this also strip leading spaces? – Hashim Aziz Dec 8 '20 at 0:38
  • 1
    @Prometheus: yes – Arkadiusz Drabczyk Dec 8 '20 at 19:58
  • What I suspected, thank you. – Hashim Aziz Dec 8 '20 at 20:05

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