BASH script w/ functions won't run on startup

Question

I have a BASH script that runs fine in terminal. But when I try to get it to run on startup, nothing happens. It seems related to the fact that the script uses functions. When I break the commands out of functions, it works as expected on startup. Any thoughts on why? Here is an example, but any arbitrary code in the function creates the same issue:

 #!/bin/bash
say-stuff () {
notify-send Stuff "Here is some stuff." 


}
say-stuff

Answer 1

There is a space before the shebang in your script - which breaks the file magic:

$ printf '#!/bin/bash\n' | file -
/dev/stdin: Bourne-Again shell script, ASCII text executable

but

$ printf ' #!/bin/bash\n' | file -
/dev/stdin: ASCII text

This causes the XDG autostart mechanism to fall back to executing the script with /bin/sh, in which say-stuff isn't a valid function name:

$ sh -c 'say-stuff () { echo "stuff"; }'
sh: 1: Syntax error: Bad function name

You can see this happening if you run xdg-autostart in an interactive terminal with a minimal .desktop file:

$ cat ~/.config/autostart/say-stuff.desktop 
[Desktop Entry]
Type=Application
Name=say-stuff
Exec=say-stuff

then

$ xdg-autostart 2>&1 | grep -A3 say-stuff
** Message: 18:23:33.620: xdg-autostart.vala:39: Processing /home/steeldriver/.config/autostart/say-stuff.desktop file.
** Message: 18:23:33.627: xdg-autostart.vala:94: Launching: say-stuff (say-stuff.desktop)
** Message: 18:23:33.627: xdg-autostart.vala:39: Processing /etc/xdg/autostart/nm-tray-autostart.desktop file.
/home/steeldriver/.local/bin/say-stuff: 3: Syntax error: Bad function name
** Message: 18:23:33.646: xdg-autostart.vala:94: Launching: nm-tray (nm-tray-autostart.desktop)
** Message: 18:23:33.646: xdg-autostart.vala:39: Processing /etc/xdg/autostart/upg-notifier-autostart.desktop file.
** Message: 18:23:33.655: xdg-autostart.vala:94: Launching: /usr/libexec/lubuntu-update-notifier/lubuntu-upg-notifier.sh (upg-notifier-autostart.desktop)

It "works" when you execute the script directly because

• say-stuff is a legal function name in bash; and

• your interactive shell is bash, and that causes the script with the invalid shebang to also run in bash

See also Which shell interpreter runs a script with no shebang?

Answer 2

Jobs run through cron, or startup scripts aren't run in the same runtime environment that you have on your desktop. Startup scripts are run as root. None of your PATH changes, or other environment variable settings from ~/.bashrc are automatically propagated to your cron job. For example, there's no $DISPLAY, so GUI programs need special treatment (read man xhost).

One can set environment variables for all one's cron jobs in the crontab file Read man 5 crontab.

Look at the results of echo "=== id ===";id;echo "=== set ===";set;echo "=== env ===";env | sort;echo "=== alias ===";alias in each of your environments.

An easy way is to store the commands in a bash script, and execute it from your terminal session, saving the output, then, execute the script from the "other" environment, saving the output. Compare the saved outputs using diff.

#!/bin/bash
echo "=== id ===";id
echo "=== set ===";set
echo "=== env ===";env | sort
echo "=== alias ===";alias`