Why this bash script doesn't run on startup?

Question

This test.sh script:

cd test-1
source .venv/bin/activate
python test.py
deactivate

runs fine from the terminal on Ubuntu 20.04.6 with this command:

nick@jetson:~$ ./test.sh

When I add it to Startup Applications Preferences with:

it doesn't run. What is wrong?

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This question is different from How do I start applications automatically on login?. I'm not asking how do I start applications automatically on login. I'm asking why a different command has to be used in Command line of Add Startup program than the command I type in the terminal in ~ folder.

Answer 1

This question is different from How do I start applications automatically on login?. I'm not asking how do I start applications automatically on login. I'm asking why a different command has to be used in Command line of Add Startup program than the command I type in the terminal in ~ folder.

When you create a "Startup application", what happens under the hood is:

1. A .desktop file is created under ~/.config/autostart, containing an Exec line that contains the "command" you specified;
2. On session's startup, the desktop file is parsed and evaluated according to Freedesktop's specifications.

Quoting the relevant section from the page (emphasys mine):

The Exec key must contain a command line. A command line consists of an executable program optionally followed by one or more arguments. The executable program can either be specified with its full path or with the name of the executable only. If no full path is provided the executable is looked up in the $PATH used by the desktop environment. The name or path of the executable program may not contain the equal sign ("="). Arguments are separated by a space.

So the reason why ./test.sh fails simply is: it doesn't comply with any of the Freedesktop's specifications, as it's neither a full path nor a name of an executable.

Also note that there are more rules that a "command" needs to abide to (you can find them in the page I linked), but going through these checks usually works:

1. If you need to run something not in PATH, you need to put in the full path, otherwise you can put in just the bare name of the executable;
2. You can't use shell-isms (variables, aliases, functions, redirections, pipes and the like). Variables can be injected into the executable's environment using env (env foo=bar executable). If you need something more, you can mostly use sh -c / bash -c (sh -c '<input command1 | command2'), or create a wrapper script around your actual script.

Answer 2

If your script really doesn't have a shebang (#!/bin/bash), one solution would be to run:

bash /home/your_username/test.sh

instead. However the "correct" solution would be to add a shebang to the script and run just:

/home/your_username/test.sh

The shebang is required in other contexts (such as when running the script from a shell that is not Bash) to make use of Bash features, such as e.g. source when the script is run from sh.