How do I run the same file with multiple shebang interpreter? - bash

Question

So suppose I want to run some commands in bash and then say, octave. Is there any way to run the same file with two different commands? In the example below I want the first part to be run by bash and the second to be run by octave
#!/bin/bash
echo helloooo
#!/bin/octave
plot(1,2)
pause()

Answer 1

There is only one shebang possible at first line of a script.
Not sure of what you want to do here, but you can use the script's name to switch the script interpreter at run-time
Exemple myscript.sh
#!/usr/bin/env bash
case "${0##*.}" in
# Switch script's interpreter based on script's name trailing .extension
sh)
echo helloooo
;;
plot | octave | oct)
octave < <(
# Remove the Bash part of this script
# by deleting lines up to what look like an octave shebang,
# and send it to octave
sed '1,/^#!.*[/[:space:]]\+octave$/d' "$0"
)
;;
esac
exit # Bash stuffs ends here
# Octave stuffs starts here with fake octave shebang
#!/usr/bin/env octave
plot(1,2)
pause()
Then create a link to your script:
ln --symbolic --force myscript.sh myscript.oct
Running it as a Bash script:
./myscript.sh
helloooo
Running as an Octave script:
./myscript.oct
...

Answer 2

You could of course just by-pass the bash script altogether and do output in octave itself. It's a neater solution.
#!/usr/bin/octave
disp('hellooo')
plot(1,2)
pause()