Cannot run 'just --init' on Termux (Android CLI)

[lyderic]

I installed Termux on my Android phone. I tried to initialise a justfile by running 'just --init' on it. It doesn't work.

Log of my actions:

$ curl --proto '=https' --tlsv1.3 -sSf https://just.systems/install.sh | bash -s -- --to ~/bin
install: Repository:  https://github.com/casey/just
install: Crate:       just
install: Tag:         1.11.0
install: Target:      aarch64-unknown-linux-musl
install: Destination: /data/data/com.termux/files/home/bin
install: Archive:     https://github.com/casey/just/releases/download/1.11.0/just-1.11.0-aarch64-unknown-linux-musl.tar.gz
install: error: just already exists in /data/data/com.termux/files/home/bin

$ just -V
just 1.11.0

$ pwd
/data/data/com.termux/files/home
$ just --init
error: I/O error reading directory `/data/data`: Permission denied (os error 13)

$ ls -l /data/data
ls: cannot open directory '/data/data': Permission denied

Notes:

• The directory I run just from (/data/data/com.termux/files/home) is definitely r/w'able
• Compiling just myself with 'cargo install just' yields the same result.
• If I manually create a justfile in /data/data/com.termux/files/home, then it works:

$ cat > justfile << EOF
> foo:
>   @echo foo
> EOF
$ just
foo

I don't understand why just tries to read this /data/data directory when initialising a new justfile...

Has anyone been able to successfully run just --init on Termux?

Thanks,
L.

[casey]

I believe the issue is that just --init tries to look for an existing justfile, and refuses to create a new one if one already exists. If /data/data isn't readable, then that initial search will fail. It partially defeats the purpose, but you could do just --init --justfile justfile

Alternatively, a simple justfile is very simple, so you could also just do echo default: > justfile

[lyderic]

Thanks for the workaround. It's working well.

[casey]

Nice!

[casey]

vv happy that just is running on an android phone somewhere ^_^

Seems like it might be a pretty good use case, since you want to minimize the amount of typing you have to do.

[lyderic]

Definitely! I find myself typing things like 'j o' or 'j r' now :-) just is a fantastic tool!

[TomJo2000]

Hi I'm currently reviewing the pull request just above (termux/termux-packages#19712).
Just wanted to pop in to ask if we should bother to patch just --init to stop at Termux's "effective root directory" (/data/data/com.termux/files/usr).

[casey]

@TomJo2000 If there's a simple and non-hacky way to detect whether we're running in Termux, and stop the search for a justfile when we hit the effective root directory, I wouldn't be opposed to it. It shouldn't just stop when it hits an error. Feel free to open an issue!

[TomJo2000]

If there's a simple and non-hacky way to detect whether we're running in Termux, and stop the search for a justfile when we hit the effective root directory, I wouldn't be opposed to it. It shouldn't just stop when it hits an error. Feel free to open an issue!

We have a variable called $PREFIX, although that name is subject to change in the future, since we've run into collisions with it before and it's generally too generic, I think generally detecting Android, and limiting the search to the bounds of the App based on the app directory would be a more generic way to handle it.

So for example our PREFIX variable is /data/data/com.termux/files/usr, but it's probably fine to search up to /data/data/{{application.name}}/, that way it isn't specific to com.termux, or our specific directory layout.

I'll need to think about this some more as I'm not exactly sure how to best handle this.

[casey]

PREFIX is a bit too generic, but if it were TERMUX_PREFIX, then it would be totally reasonable to stop searching when just hits TERMUX_PREFIX.

[TomJo2000]

PREFIX is a bit too generic, but if it were TERMUX_PREFIX, then it would be totally reasonable to stop searching when just hits TERMUX_PREFIX.

I think the current replacement candidate is TERMUX__PREFIX, but there isn't a timeline on that being changed.
So I think a generic "we're running on Android, let's stop at the app directory" approach might be better in this situation.

[casey]

Is there an easy way to get the app directory on android? Is /data/data always the location of the app directory? Are /data and / accessible, i.e., does just finish searching for a justfile successfully in those locations? Another option is to treat permission errors on /data/data on android as a special case.

[TomJo2000]

As far as I know everything outside of /data/data/{{app.name}} is read-only so can be ignored for our purposes here.
But I work on the packaging end of things, not app development, so I'm not 100% sure on that.
There definitely wouldn't be any just files expected outside of the app's directory though.