On 2022-01-02 at 17:52, Paul M. Foster wrote: > Folks: > > In a script, I'd like to search for a pattern in a file, and replace > that line entirely with a new line, once (not globally). I've tried What do you mean by "globally"? If you mean that you want to only replace the first matching line in the file, but leave any subsequent matching lines alone... I've never actually had occasion to do that, but a bit of Googling (for 'sed first match only') found me https://stackoverflow.com/questions/148451/how-to-use-sed-to-replace-only-the-first-occurrence-in-a-file which looks like at least the seed of a way to do it; see also below. > sed -i s/search/new_line/ > > but this only replaces the string itself. I want the script to find the > line my search term is on, and replace the whole line with my > replacement line. > > Anyone know how to do this? Without re-testing at the moment, I'd say from past experience that you want: sed -i 's/^.*search.*$/new_line/' This matches the beginning of the line, followed by zero or more characters, followed by the search string, followed by zero or more characters, followed by the end of the line. Whether or not the quotes are necessary depends on what your 'search' and 'new_line' strings consist of, but I habitually include them just to be on the safe side. There may well be ways to do this more readily using other tools, but I don't know them off the top of my head, and that should be the way to do it using sed. Combining this with the suggestion from the link above would produce something like: sed -i '0,/^.*search.*$/{s/^.*search.*$/new_line/}' I have *not* tested that, since I don't have a suitable test input file ready to hand and don't feel like throwing one together right at the moment, but it looks like it should produce the desired result. -- The Wanderer The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. -- George Bernard Shaw
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