# Q about git rev-parse {--is-inside-work-tree, --show-cdup} 6 messages from 2010-12-03 to 2010-12-04. Participants: Dirk Süsserott, Jeff King, Junio C Hamano, Andreas Schwab. Thread: https://gitlist.dev/t/25945 ## Dirk Süsserott, 2010-12-03 21:06 Subject: Q about git rev-parse {--is-inside-work-tree, --show-cdup} Message-ID: <4CF95BDC.60506@dirk.my1.cc> URL: https://gitlist.dev/e/4CF95BDC.60506%40dirk.my1.cc ``` Hi together, I wrote some shell scripts that do sth with my git repositories. I place my scripts in my ~/bin folder (not in the repo). So the first step in my scripts is always to check whether they get called from whithin a git repo and bail out if they don't. I do this like so: --------------------- if [ "$(git rev-parse --is-inside-work-tree)" = "true" ] # (1) then here=$(pwd) cdup=$(git rev-parse --show-cdup); # (2a) cdup=${cdup:-"."} # (2b) cd $cdup # (2c) [do sth useful from the topdir] cd $here exit 0; else echo "Not inside a git working tree." exit 1; fi --------------------- I have two questions: 1. Wouldn't it be useful, if "git rev-parse" (1) had an option "-q" that simply indicates whether "--is-inside-work-tree" is true by means of the return code? Actually it has an option "-q" but that doesn't work with "--is-inside-work-tree". 2. Wouldn't it be useful, if "git rev-parse --show-cdup" (2a) would return a dot "." instead of nothing if we are already in the topdir? That would make the steps (2a), (2b), (2c) to a simple "cd $(git rev-parse --show-cdup)". (For those who aren't familiar with shell programming: (2b) means: 'if $cdup is empty, then set it to "."'.) I know that 2. is a problem, because "git rev-parse" is a plumbing tool. People likely rely on "--show-dup" to return an empty string. But what about 1.? I think there's no harm if "-q" would work for "--is-inside-work-tree" as well. BTW: I'm sorry that all my sentences start with "I". ;-) What do you think? If appreciated, I'd like to work on a patch for (1). Cheers, Dirk ``` ## Jeff King, 2010-12-03 21:20 Subject: Re: Q about git rev-parse {--is-inside-work-tree, --show-cdup} Message-ID: <20101203212035.GB2632@sigill.intra.peff.net> URL: https://gitlist.dev/e/20101203212035.GB2632%40sigill.intra.peff.net In-Reply-To: <4CF95BDC.60506@dirk.my1.cc> ``` On Fri, Dec 03, 2010 at 10:06:36PM +0100, Dirk Süsserott wrote: > I wrote some shell scripts that do sth with my git repositories. I place > my scripts in my ~/bin folder (not in the repo). So the first step in my > scripts is always to check whether they get called from whithin a git > repo and bail out if they don't. > > I do this like so: > > --------------------- > if [ "$(git rev-parse --is-inside-work-tree)" = "true" ] # (1) > then > here=$(pwd) > cdup=$(git rev-parse --show-cdup); # (2a) > cdup=${cdup:-"."} # (2b) > cd $cdup # (2c) > > [do sth useful from the topdir] > > cd $here > exit 0; > else > echo "Not inside a git working tree." > exit 1; > fi > --------------------- Since you are writing shell scripts, you may be interested in doing: . git-sh-setup require_work_tree cd_to_toplevel > 1. Wouldn't it be useful, if "git rev-parse" (1) had an option "-q" that > simply indicates whether "--is-inside-work-tree" is true by means of the > return code? Actually it has an option "-q" but that doesn't work with > "--is-inside-work-tree". Yeah, in general rev-parse's "-q" is annoying. It only works with checking revisions (like "git rev-parse -q --verify HEAD"), and it probably should apply to a lot more. Patches welcome. > 2. Wouldn't it be useful, if "git rev-parse --show-cdup" (2a) would > return a dot "." instead of nothing if we are already in the topdir? > That would make the steps (2a), (2b), (2c) to a simple "cd $(git > rev-parse --show-cdup)". I'm hesitant to change it, as that is a public interface for shell scripts. However, there is also "--show-toplevel" which will do what you want in one line (or just cd_to_toplevel as I mentioned above). > What do you think? If appreciated, I'd like to work on a patch for (1). Please do. -Peff ``` ## Junio C Hamano, 2010-12-03 21:25 Subject: Re: Q about git rev-parse {--is-inside-work-tree, --show-cdup} Message-ID: <7v4oauo8fj.fsf@alter.siamese.dyndns.org> URL: https://gitlist.dev/e/7v4oauo8fj.fsf%40alter.siamese.dyndns.org In-Reply-To: <4CF95BDC.60506@dirk.my1.cc> ``` Dirk Süsserott writes: > Hi together, > > I wrote some shell scripts that do sth with my git repositories. I place > my scripts in my ~/bin folder (not in the repo). So the first step in my > scripts is always to check whether they get called from whithin a git > repo and bail out if they don't. > > > I do this like so: > > --------------------- > if [ "$(git rev-parse --is-inside-work-tree)" = "true" ] # (1) > then > here=$(pwd) > cdup=$(git rev-parse --show-cdup); # (2a) > cdup=${cdup:-"."} # (2b) > cd $cdup # (2c) > > [do sth useful from the topdir] > > cd $here > exit 0; > else > echo "Not inside a git working tree." > exit 1; > fi > --------------------- > > I have two questions: > > 1. Wouldn't it be useful, if "git rev-parse" (1) had an option "-q" that > simply indicates whether "--is-inside-work-tree" is true by means of the > return code? Actually it has an option "-q" but that doesn't work with > "--is-inside-work-tree". That would break existing scripts that expect "-q" to squelch only the error output, no? I think the risk of breaking existing scripts that other people wrote over time that you (and I) haven't seen outweighs any benefit (i.e. "if test $(rev-parse...) = true" vs "if rev-parse...") you are seeing here. Another thing to consider is what the script should do when rev-parse detects an error. Do we know that all scripts want to behave exactly the same way in two cases: (1) when run outside the work tree; and (2) when they cannot determine if they were run from inside or outside? I don't think so. In your example, you are only interested to work inside work tree, and you may find "if rev-parse... then do this interesting thing else fail fi" sufficient, but a script by somebody else may want to make sure that it is not run inside any git controlled working tree, and it cannot say "if rev-parse then punt else do this big thing fi" is not an appropriate way to write it. So in that sense, "if rev-parse ..." is not a huge improvement to begin with, for people who want to write their script strictly. They would probably need to say something like: ans=$(git rev-parse ...) || { do the error thing exit 1 } case "$ans" in true) do the inside-work-tree thing ;; false) do the outside-work-tree thing ;; *) do the oops thing;; esac ``` ## Jeff King, 2010-12-03 21:50 Subject: Re: Q about git rev-parse {--is-inside-work-tree, --show-cdup} Message-ID: <20101203215032.GB3972@sigill.intra.peff.net> URL: https://gitlist.dev/e/20101203215032.GB3972%40sigill.intra.peff.net In-Reply-To: <7v4oauo8fj.fsf@alter.siamese.dyndns.org> ``` On Fri, Dec 03, 2010 at 01:25:36PM -0800, Junio C Hamano wrote: > > 1. Wouldn't it be useful, if "git rev-parse" (1) had an option "-q" that > > simply indicates whether "--is-inside-work-tree" is true by means of the > > return code? Actually it has an option "-q" but that doesn't work with > > "--is-inside-work-tree". > > That would break existing scripts that expect "-q" to squelch only the > error output, no? I think the risk of breaking existing scripts that > other people wrote over time that you (and I) haven't seen outweighs any > benefit (i.e. "if test $(rev-parse...) = true" vs "if rev-parse...") you > are seeing here. Right now "-q" doesn't do _anything_ for --is-inside-work-tree, AFAICT. It is a useless no-op. So I don't know if we are breaking anybody. What does somebody doing "git rev-parse -q --is-inside-work-tree" expect to happen? I don't see why they would expect it to suppress error output. Usually "-q" is about "suppress non-essential output, but keep errors coming". If you wanted to suppress errors, you would use "2>/dev/null". That being said, in my original reply I only half-thought about Dirk's problem, and considered more the number of times "git rev-parse -q" has annoyed me in the past by doing nothing[1], and just assumed this was another such case. It really isn't that hard to just check $(git rev-parse) in this instance. -Peff [1] I wish I could remember my exact case. It's something that I remember coming up no more than once every month or two, but that annoys me every time, because it doesn't do what I expect. -Peff ``` ## Dirk Süsserott, 2010-12-04 15:12 Subject: Re: Q about git rev-parse {--is-inside-work-tree, --show-cdup} Message-ID: <4CFA5A67.2020108@dirk.my1.cc> URL: https://gitlist.dev/e/4CFA5A67.2020108%40dirk.my1.cc In-Reply-To: <20101203215032.GB3972@sigill.intra.peff.net> ``` Am 03.12.2010 22:50 schrieb Jeff King: > On Fri, Dec 03, 2010 at 01:25:36PM -0800, Junio C Hamano wrote: > >> That would break existing scripts that expect "-q" to squelch only the >> error output, no? I think the risk of breaking existing scripts that >> other people wrote over time that you (and I) haven't seen outweighs any >> benefit (i.e. "if test $(rev-parse...) = true" vs "if rev-parse...") you >> are seeing here. > > Right now "-q" doesn't do _anything_ for --is-inside-work-tree, AFAICT. > It is a useless no-op. So I don't know if we are breaking anybody. What > does somebody doing "git rev-parse -q --is-inside-work-tree" expect to > happen? > Peff, Junio, thanks for your answers. I already had a suspicion that changing plumbing tools like rev-parse was a bad idea. You confirmed that. However, I still think it's a little bug that "--show-dup" returns an empty string instead of a dot when already in topdir. But it's too late to change that, I guess. I didn't know about Peff's suggestions "git-sh-setup" and "--show-toplevel". They may help me. @Peff, right, it's annoying that -q sometimes works and sometimes doesn't. To my opinion switches like --quiet and --verbose should _always_ work. Dirk ``` ## Andreas Schwab, 2010-12-04 16:52 Subject: Re: Q about git rev-parse {--is-inside-work-tree, --show-cdup} Message-ID: URL: https://gitlist.dev/e/m24oatcwfa.fsf%40igel.home In-Reply-To: <4CF95BDC.60506@dirk.my1.cc> ``` Dirk Süsserott writes: > 2. Wouldn't it be useful, if "git rev-parse --show-cdup" (2a) would > return a dot "." instead of nothing if we are already in the topdir? > That would make the steps (2a), (2b), (2c) to a simple "cd $(git > rev-parse --show-cdup)". The string returned by --show-cdup is to be used as prefix for a relative path. If you want to use it standalone just append ".": cd $(git rev-parse --show-cdup). Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." ```