On Tue, Feb 23, 2021 at 04:33:44PM -0500, Chet Ramey wrote: > On 2/22/21 8:11 AM, Mike Jonkmans wrote: > > > > Hi, > > > > It seems some things are missing in the bash manual. > > Notably definition of command and placements of coproc- and > > function-definition. > > > > The section 'SHELL GRAMMAR' describes: > > - simple-command > > - pipeline > > - list > > - compound-command > > - coproc > > - function-definition > > These are basically the `command' productions from the grammar. The > exception is `list', and it's there because it would be strange for > the reader if it were presented before simple commands and pipelines, > which users are more likely to encounter, even though a complete > command is technically a list.
It is mostly recursive, so you have to start somewhere. Your reasoning is understandable. Start with what the reader knows. Though the readers are likely to be familiar with grammars/rules/start symbols. Because 'command' is not described, a reader might think that all these items are commands. > > Simplified, a pipeline is: > > [ ! ] command1 [ | command2 ] > > > > A list is a sequence of pipelines separated by ;, &, &&, or || > > and optionally terminated by ;, & or NL. > > > > Within the list description, the and-list and or-list are described as: > > and-list: command1 && command2 > > or-list: command1 || command2 > > Though the text says that and/or-lists are sequences of pipelines > > (separated by && or ||). > > `command1' and `command2' are meta-notation, not a grammar production. I know. It is just as the man page describes it. The numbering is quite handy for referring in the text. > > That is slightly inconsistent. > Not really. > > > A pipeline can be reduced to a command. > In a sense, yes, depending on your definition of `command'. That is the point. The documentation never describes what a 'command' is. The inconsistency comes when you try to follow the documentation's use of 'command'. It is only in the words, not in the real grammar of course. > > In that case, the and/or list should read: > > and-list: pipeline1 && pipeline2 > > or-list: pipeline1 || pipeline2 > > No, it really shouldn't. You're right. These pipelines should be lists. In the mean time i have looked into parse.y The grammar is quite readable. Good. > The bash grammar is a little messier than that POSIX grammar in > https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_10_02 > but it's basically the same. Thanks for the link. > Where are you trying to go with this? I have been wondering about this (missing command description) for some time. Before even trying to submit a rewrite, i wanted to make it more clear. For me, it is clear now. But i am not sure whether a rewrite is worth the trouble. It is also a bit problematic that the word 'command' is overloaded. We give commands, not lists. Though a pipeline might be entered ;) Regards, Mike Jonkmans
