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For the regular expression to only match a full field of hyphens, you have, as others already have explained, to put the ^ anchor at the begin of the regular expression and the $ anchor at the end ...
Answer
#1: Initial revision
by
Dirk Herrmann
·
2022-04-15T19:32:54Z (about 2 years ago)
For the regular expression to only match a full field of hyphens, you have, as others already have explained, to put the `^` anchor at the begin of the regular expression and the `$` anchor at the end and make it clear that you are interested in a sequence of hyphens by adding a `+` after the hyphen.
There is, however, one additional aspect that may be of interest for you: Instead of using `gsub` for both the matching *and* the replacement you could separate these two aspects in the following way:
awk 'BEGIN{FS=OFS="\t"}$72~/^-+$/{$72=""}1' file.tsv
The expression `$72~/^-+$/` will match those lines where field `$72` consists of only hyphens, and the action `{$72=""}` clears field `$72`. This approach gives you the freedom to choose some different action on those lines than only deleting the field content. This can be of interest if, for example, you do not only want to clear the field, but also get rid of the surrounding field separators or the like.