I'd really like to understand the underlying reasons why some scripts work from the command line but not when double-clicked.

Is there an example of a script that does something simple, like echoing a variable or something like that, which would reproducibly work in the command line, but then fail to work when double-clicked?

To be clear, I mean it should run in both instances, but when double-clicked it should fail to perform its task correctly, and it should do this on any recent Ubuntu installation. I'm hoping that by being able to reproduce the behaviour I can understand it and fix it myself in the future.

1

2 Answers

Easiest example:

• create a file "test" and put

  #!/bin/bash
  echo "Hello World!"

  in it

• make it executable with chmod 700 test

• do ./test on commandline and it will output

  Hello world!

From Nautilus:

• default: doubleclick and it will open as a text file
• when set to "run text files" from Nautilus preferences it will flicker a couple of times and then does nothing.

But this is intended behaviour. For Nautilus you would need to create a script that does a "pop up" with the text "Hello world!" in it.

Example:

#!/usr/bin/python
import os
os.system('zenity --info --text="Hello world!!"')

would show ...

By the way: this also works from command line when you have a desktop. On a tty it would show an error "Failed to connect to Mir".

and fix it myself in the future

I doubt though there is something to fix. Executing in command line and executing in Nautilus are 2 different things.

2

Ok I think I've got the answer... at least this solves my problem and along the way I stumbled on this and thought I would come back and post an answer.

Shell scripts do not have the same $PATH variable that the terminal does. I can change that for the purpose of the script (in my case using Jupyter notebook as an example) by doing this:

#! /usr/bin/env sh
#this adds the location where jupyter command is found
export PATH="/home/username/anaconda3/bin:$PATH"
jupyter notebook

and that will work.

Additionally some programs may need the terminal to interact with so you could do something like:

#! /usr/bin/env sh
#this adds the location where jupyter command is found
export PATH="/home/username/anaconda3/bin:$PATH"
xterm -e "jupyter notebook" # brings up a terminal window

And that will bring up a terminal window to display output and receive input.

Edit: I changed for completeness.

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