Le 20/05/2018 à 18h03, Paul Eggert a écrit : > Garreau, Alexandre wrote: >> I believe context options used in conjonction with invert-match option >> should specify which lines*not to show* along with matched then not >> shown lines. > > I can see it the other way. For example, "show all lines that lack > signed integers, plus their context" can be done via a command like > "grep -C1 -v -E > '[-+][0-9]+([^.e]|$)'", and I don't see any easy way to do the same > search under the changes you're proposing.
Oh in fact, I didn’t notice it actually had this effect… in fact when only a few lines don’t match, especially when they’re not contiguous, using -v with context options nearly equals not using grep at all… turns out I narrowed enough my mind to miss this. > In essence you're proposing a new feature that I'd call "negative > context"; i.e., if a line is not selected, then suppress the output of > nearby lines that are selected. grep already has a lot of features and > it's not clear this one is important enough to add. My memory is bad, but grepping at looking at my history for when I made up this example says me I needed this feature for something like this:
apt search programming ant | grep -v '^lib' -A 2 | less
Here I guess we’re in a case where sed would be better suited… like a bunch of today’s features of grep (invert-match, personally I believe it would naturally be handy with it): they both come from ed after all. But this seems to be, as coincidently said today on #emacs (and later outside I heard [1]), a case of:
[CEST] [03:16:37] <JordiGH> Don't you love it when you have commands like [03:16:54] <JordiGH> do_the_thing --nope-this-option-makes-me-do-the-opposite-of-the-thing [03:17:00] <JordiGH> Currently thinking of [03:17:07] <JordiGH> ssh-keygen -R [03:17:13] <chu> It's the Unix way [03:17:14] <JordiGH> That -R makes it delete a key instead of generating one. [03:17:55] <twb> ssh-keygen is a random grab-bag utility that does lots of things, and yes, it's dumb [03:18:13] <JordiGH> It's the git way. [03:19:16] <JordiGH> sort --random-sort […] [03:19:24] <JordiGH> Isn't that, like, the opposite of sorting? [PS : JordiGH agreed to be quoted in pm, and before that] [06:37:04] <galex-713> twb: can I quote you too? [06:38:11] <galex-713> chu: what about you then, too? [06:38:41] <twb> galex-713: sure, you can quote that [08:20:01] <chu> galex-713: it's fine
>> maybe this behavior could be triggered only >> if the context option were specified *after* the invert-match one > > I'd prefer option order to not matter, at least when options do not > simply override each other (as is the case here). Agree, would add more complexity of use. And keywords are made to get rid of order considerations anyway. [1] Unix options that make commands do the opposite of their name: <https://mathstodon.xyz/@JordiGH/100064804426272107>
