[Toybox] Allow --help after other arguments?

enh enh at google.com
Mon Jun 14 14:03:59 PDT 2021

On Sun, Jun 13, 2021 at 2:49 AM Rob Landley <rob at landley.net> wrote:

> On 6/11/21 4:51 PM, Ryan Prichard wrote:
> > On Thu, Jun 10, 2021 at 7:05 PM Rob Landley <rob at landley.net
> > <mailto:rob at landley.net>> wrote:
> >     to show the help for ls. And DON'T want "chroot dir ls --help" to
> show help
> >     output for chroot. (Or time. Or nice. Or nohup...)
> >
> >
> > Yeah, I think my ideal would be for --help to apply to the last
> (sub)command
> > preceding it. e.g. When it appears after a subcommand name, it would be
> parsed
> > like any other subcommand flag. For "time", flag parsing (for -p and -v)
> seems
> > to stop at the first non-hyphenated argument.
> Which pulls in the argument parsing as a prerequisite for --help support in
> commands like dd, expr, test...
> Sigh. It's possible this is an acceptable cost, I'd just really like to
> avoid it
> if I can. It's that whole "project serving two masters" thing again. The
> embedded space is weird. Yes you can fit the computing power of a
> supercomputer
> into a wristwatch, at the expense of the watch's battery life being about 3
> hours of actual usage and 12 hours on standby. My mental model has been the
> "free toy inside" of a cereal box running two chips off a watch battery. A
> modern version of the blinking LED that was in everything in the 90's. [1]

how much of toybox is even buildable (let alone usable!) without Linux or
equivalent Unix-y kernel? and afaik you can't run Linux [or equivalent] on
any of the Cortex-M series, let alone the 8-bit AVR series or whatever else
lives in the sub-Cortex-M realm?

(maybe things are different in the SH world? TIL^Wlast week i learned [when
skeptical of your claim about generating the md5sum.c tables] that SH-4 has
a sincos instruction! i don't know of any ARM cores with anything like
that. sqrt is about as fancy as they get.)

and aren't the "free toy inside" crowd even _more_ likely to have one
multiplexer binary than others? only folks with disk and memory to throw
away will build n separate tools?

> > Aside: "toybox toybox toybox toybox ls" doesn't seem to work for me:
> >
> > $ toybox toybox toybox toybox ls --help
> > toybox: Unknown command toybox (see "toybox --help")
> Ah, I forgot commit 28c9710edf8b changed that.
> >     The reason that --help isn't in the argument parsing plumbing is
> because then
> >     commands that don't have arguments wouldn't support --help, not
> without the
> >     argument parsing plumbing being unable to drop out when building
> small binaries.
> >
> >
> > I'm wondering when it's useful to drop the argument parsing plumbing. Is
> there a
> > configuration where CFG_TOYBOX is off, and there is one binary for one
> command?
> You can make individual command names, or "make change" to do each
> individual
> command in a loop. (Both are listed in "make help".)
>   $ make crc32
>   ...
>   $ nm --size-sort generated/unstripped/crc32
> (Might wanna pipe that to grep -v ' [Bb] ' because bss only exists at
> runtime,
> not in the binary...)
> > Most of the commands take arguments, so I'd think most builds of the
> toybox
> > binary would need some amount of the plumbing.
> Most builds use the multiplexer where the infrastructure is shared between
> all
> the commands, but a lot of small systems cherry pick just the commands they
> need. Still, the list of commands that when build standalone don't include
> lib/args.c is currently:
>   $ grep 'NEWTOY(' toys/*/*.c | grep -v '["]' | grep -v NOHELP | \
>     grep -v NOFORK | sed 's/.*NEWTOY(\([^,]*\),.*/\1/p' | sort -u | xargs
>   arch ascii bootchartd bzcat clear count crc32 dd demo_scankey
> demo_utf8towc
>   dos2unix expr factor groups hello ip lsmod lsusb more readahead reset
> rev sync
>   tac unix2dos w xzcat yes
> Which isn't a huge list. (And half that's in pending or example anyway.)
> I suppose I could make if/else logic for the drop out case still supporting
> --help. I wince at this but lemme think about it.
> >     > $ ./tar -c README > --help && ./tar -tvf --help
> >     > <prints "toybox tar" usage with the new --help behavior.
> previously toybox
> >     > behaved like GNU tar above.>
> >
> >     And now you know why I had it the way it was. It sounds like what
> you're saying
> >     is that the toysh "alias" command should be --help aware for
> builtins.
> >
> > Ah, I don't think I'd make a special case for alias... not sure how that
> would work?
> I'm writing a shell as we speak, so... :)
> (Alias is in the near term todo heap but I need to get through job control
> first. Job control is a gordian knot I don't get to cut, but there are some
> interesting solvents...)
> > So... I don't actually use alias on Android devices. I had suggested it
> as an
> > example that might motivate "ls -l --help" more strongly than
> convenience and
> > expectation. I'm happy enough just editing the --help into the right
> place on
> > the command line.
> I try to have multiple ways:
>   toybox --help ls
>   toybox ls --help
>   ls --help
>   help ls
>   toybox help ls
> Plus the "man" command someday...
> > -Ryan
> >
> Rob
> Footnote 1:
> We've run j-core with an ice-40 wired to an spi flash chip and had it
> export an
> spi interface to read from a calculator keyboard/display running off a
> stack of
> 3 watch batteries. We haven't YET taped the ice40/spi pair to the front a
> watch
> battery and added an LED and IR sensor as a proof of concept to have a
> coin cell
> run gnuchess all by itself, but that's mostly because you'd have to stack
> 3 coin
> cells to get the voltage the ice40 wants (and adding voltage converter
> circuitry
> would defeat the "two chips scotch taped to a battery bigger than the
> chips are"
> bragging rights thing), so that'll have to wait for an asic SOC version...
> You can get tiny processors for 3 cents
> (https://www.youtube.com/watch?v=VYhAGnsnO7w) and a quick search found
> coin cell
> batteries for 36 cents each retail
> (
> https://www.amazon.com/Panasonic-Cr2032-Lithium-Battery-Ecr2032/dp/B00REWNF2M/ref=asc_df_B00REWNF2M/
> )
> presumably cheaper in bulk. (I occasionally look at
> htts://landley.net/notes-2017.html#30-09-2017 and such but "woman invents
> a
> thing, white dude takes credit, his company gets sued for treating
> employees
> terribly and goes bankrupt" is a sadly common story...)
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