Support for Termux

[hsoler]

Context:
Hello, I'm trying to install this library through pip in Termux.

Problem:
The which_shell function in setup.py points to /bin/sh, which is Dash, and Dash is incompatible with build.sh in rl, which relies on Bash features. Also, it is very hard to change /bin/sh to point to Bash instead of Dash.

Solution #1:
Change build.sh to be compatible with Dash. I rather Solution #2, below:

Solution #2:
Before trying to find the Bash file from the addresses /bin/bash, /usr/bin/bash and /usr/sh as is now, try to issue the command which bash, which should woirk by default in most Unix distributions and should work in Termux after running pkg install which (tested here). Bonus points: this should handle other use cases where Bash can't be found in the traditional spots.

[hsoler]

Also, I forgot to say, but I'm a pip noob, so I'm not confident in testing changes, henceforth I'm not issuing a PR.

[hsoler]

Another solution which just came to mind, but I still rather Solution #2:

Solution #3:
Before looking at /bin/sh, look at /data/data/com.termux/files/usr/bin/bash which seems to be where bash is default installed in Termux

[ludwigschwardt]

Thanks for the report, hsoler!

Let me understand you correctly...

• You are running Termux with a default Dash shell in /bin/sh, right? Do you also have Bash installed? I'm not sure the tab completions will work with Dash if that's what your interactive Python shell runs under. I guess we can find out :-)
• Your issues are with building the binary package. What architecture are you running (e.g. as reported by uname -a)? Maybe we can ensure that there is a prebuilt wheel, which will also make your problem go away.
• Could you provide some output of a failing build.sh? It might not be as hard to fix it.

[hsoler]

Output of uname -a:

Linux localhost 3.18.124-perf-gc02fb4e3ca0b-dirty #1 SMP PREEMPT Wed Sep 22 11:46:47 CDT 2021 aarch64 android

(no idea what it means)

Output of failing build.sh:

./build.sh: 6: [: Linux: unexpected operator

(according to my research, this is Dash failing to understand [, which is a Bash operator)

Output of some commands runs from inside the python interpreter:

echo $0
-->
sh
0
;
echo $SHELL
-->
/data/data/com.termux/files/usr/bin/bash
;
ps -p $$
-->
PID TTY TIME CMD
1327 PTS/0 00:00:00 sh
;

I fear python interpreter is running inside Dash, yikes

[ludwigschwardt]

Interesting!

I've tried to reproduce your setup on a Linux server. I ran pip3 install --user . inside a Dash shell and it worked fine 🤔

The output of uname -a tells me you have a Linux aarch64 architecture. Technically there should be a binary wheel for you (e.g. gnureadline-8.2.13-cp312-cp312-manylinux_2_17_aarch64.manylinux2014_aarch64.whl). That means that pip shouldn't be recompiling from the source package. Maybe the manylinux part doesn't agree with your system? Or you are running Python 3.14 😂

The [: Linux: unexpected operator error in build.sh is also an interesting one. Technically [ is not an operator inside Bash but rather an executable file called /bin/[... This made me chuckle when I first released it 😅 Your installation is probably missing it.

If you could somehow start Bash just to build and install the package, that would also potentially solve your problem.

An important question, though, is: do you really need this package? It looks like Termux is GPL licensed, which is compatible with GNU readline. It also supports bash. Wouldn't the standard Python on Termux already have GNU readline enabled?

Have a look at the output of python -c "import readline; print(readline.__doc__)".

[hsoler]

Output from python -c "import readline; print(readline.__doc__)":

Importing this module enables command line editing using GNU readline

I think you are correct, my system probably doesn't need to install gnureadline from pip.

For whatever reason, the requirements.txt file in the project I'm trying to install wants to build gnureadline (linux) or pyreadline (windows) from source regardless, so I just deleted this dependency and assumed the system will work fine.

If the project fails to run for whatever readline-related issue, I will come back with runtime errors instead of build errors. In any case, I think the current issue is solved for me.

Can I provide some financial contribution to the project as a way of saying thanks?