On Sat 31 Aug 2019 at 09:02:07 (-0400), Roberto C. Sánchez wrote: > On Sat, Aug 31, 2019 at 08:39:56AM -0400, The Wanderer wrote: > > On 2019-08-31 at 07:58, Roberto C. Sánchez wrote: > > > On Sat, Aug 31, 2019 at 01:49:20PM +0200, Computer Planet wrote: > > > > > >> Hi guys! Is It possible, with "sed" erase all after a pattern? I'm > > >> trying in all way but I can't... I'd like to erase all after the > > >> pattern "config=" but only in the same line, regardless of where it > > >> is located inside in a file. > > >> > > >> Can somebody help me please? Thank in advance for reply. > > >> > > >> e.g.: after "config=" erase all until the end of the line > > > > > > Something like this: > > > > > > sed -E 's/(.*config=).*/\1/' > > > > Or perhaps > > > > sed 's/config=.*$/config=/g' > > > > ? > > > > Less elegant and idiomatic, but could also get the job done. > > > OK. > > > The 'g' at the end is in case there can be multiple occurrences of > > 'config=' in a single file, so that sed won't stop after the first one > > it finds. > > > That's not how 'g' works. It is global replace of all occurences of the > patter in the pattern space. By default, sed operates one line at a > time so the replacement will happen on every line that matches the > pattern even without the 'g'. > > $ cat ~/test.txt > Test config=foo > Test config=foo > Test config=foo > $ sed 's/config=.*$/config=/g' ~/test.txt > Test config= > Test config= > Test config= > $ sed 's/config=.*$/config=/' ~/test.txt > Test config= > Test config= > Test config= > > Since the desired effect is "replace everything to the end of the line" > then the 'g' has no practical effect. It is not really possible to have > multiple patterns match to the end of the line, unless you were trying > to do some form of relucant matching.
I wasn't aware that sed could do reluctant (or non-greedy) matching. IOW there's no .*? pattern like there is in grep. I've always used [^… … …] patterns instead where possible, or switched to python (perl in the past). As for g, yes, it's intended for things like $ sed -e 's/ 1/ /;' <<<'9 10 11 12 13' 9 0 11 12 13 $ sed -e 's/ 1/ /g;' <<<'9 10 11 12 13' 9 0 1 2 3 $ Cheers, David.
