On 01/10/12 21:54, Junio C Hamano wrote: > Now you lost me. The documentation of PROMPT_COMMAND in "man bash" > says this: > > PROMPT_COMMAND > If set, the value is executed as a command prior to > issuing each primary prompt. > > So yes, if you say "PROMPT_COMMAND='whatever'", you will get output > from 'whatever' followed by what $PS1 would normally give you. > If you do not want to see PS1 after 'whatever' gives you, you have > to set it to an empty string. > > On the other hand, they way people have been using __git_ps1 is (as > described in the prompt script) to do something like this: > > PS1='...cruft... $(__git_ps1 "%s") ...cruft...' > > To keep supporting them, __git_ps1 has to be a function that writes > the prompt string to its standard output. The external interface of > PROMPT_COMMAND also is that it wants a command that emits the string > desired for the prompt to its standard output. I do not see any > "when it is used like this, X, but when it is used like that, Y" > kind of issue around it, either. > > So what is the problem???? >
Well, I hadn't thought about that way of using it. It works in a way... But PS1 is set and interpreted in a special way by bash (I gather from examples, I'm kind of confused by it). It's possible to set PS1 to nothing and print a string from PROMPT_COMMAND, but then you miss out on all the features of the PS1 interpretation by bash and compared to the use of __git_ps1 at the moment, it has to put out quite a different string. Because if you like to see user@host+workdir (git-status)[$#] the current users of __git_ps1 say PS1="\u@host+\w $(__git_ps1 "%s")\$ ", but all __git+ps1 has to put out is "(branch)" or "(branch *)", etc. If it has to print the same prompt in PC mode, it has to add all the user/host/workdir/[$#] data as well, withouth being able to use the bash internal interpretation (because that is only working when PS1 is set). The example(s) I found when googling for a solution were to set PS1 inside the PC function, in a way that it was possible to add color encodings, without messing up the wrapping. This is _impossible_ using command substitution, because then bash doesn't interpret the \[ and \] around the color codes, and that messes up the accounting of how long the prompt string is. /Simon -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
