I have some tasks that I like to do using Emacs on several different operating systems. I have been using Termux so that I can access these tasks on my Android phone. To reduce setting-up typing in the file-editing part of this workflow, I've installed Termux:Widget and written a two-line widget script that does
filename=$(a little shell logic)
So now my phone has a button on the home screen that I can push and it opens up the file that I want in the editor. That part all works fine.
Frequently, once I've started editing, it's convenient to run a shell script. It's nice to be able to run the shell script in an Emacs buffer so that I can use the regular buffer-switching commands to interact with it. If I open a fresh Termux session and type
emacs at the prompt, then I can do
M-x async-shell-command, use relative filenames and tab completion to find the name of the script that I want (e.g.
../my-script.sh), and execute it from within Emacs. That part works fine.
However, if I've started Emacs from Termux:Widget, Emacs is unable to spawn subprocesses. I get errors like
/data/data/com.termux/files/usr/bin/sh: 1: ../my-script.sh: not found
/data/data/com.termux/files/usr/bin/sh: 1: /data/data/com.termux/files/home/whatever/my-script.sh: not found
I believe the relative and absolute path names are correct because I am using tab-completion to check them before asking to execute.
This seems like the kind of problem that termux-exec was invented to fix. However, it isn't working by magic, and I'm finding myself confused by the documentation.