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Comments on How to delete contents of a specific field, if it matches a pattern and there is nothing else in the field
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How to delete contents of a specific field, if it matches a pattern and there is nothing else in the field
How do I delete contents of a specific field, if it matches a pattern, and there is nothing else in the field? I have a several GB tsv file, and I am interested in a specific field (72). If it contains hyphens, and only hyphens, then I want the hyphens deleted, leaving a blank field. I am using Ubuntu 20.04, with GNU awk v5. I've tried something like this:
awk 'BEGIN{FS=OFS="\t"}{gsub(/-/,"",$72)}1' file.tsv
But that also deletes the hyphens if there are other characters in the field too, which I do not want. E.g.
blah------
becomes
blah
but I want to leave it unchanged; but change
---------------
to nothing.
Post
You're matching the regex pattern of /-/, so it just matches every individual hyphen, regardless of where. You want to match the entire entry if it's only hyphens, or /^-+$/.
^ – Beginning of line
-+ – One or more hyphens
$ – End of line
Putting that in gives
awk 'BEGIN{FS=OFS="\t"}{gsub(/^-+$/,"",$72)}1' file.tsv
which does what you want.
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