I repeat: " Unless #!interpreter_path starts in column 1 on the 1st line in your file, that line is just a comment and has absolutely no effect on what interpreter will be used to run your script." A leading space makes a HUGE difference. Any attempt on any UNIX-like operating system to exec a shell script that does not have #! as the 1st two characters in that file will be run by that system's default shell.

If the #!/interpreter/path start in the 1st character of the 1st line of your file and the operating system doesn't find an executable file with that path, you're likely to get a cryptic message like:

Code:

-bash: script_file not found

(assuming that your login shell is bash and the name of the shell script you were trying to execute was named script_file).

With the space there, another operating system (or your own) will know exactly what shell to use to invoke your script (that system's default) which will probably be named sh and might or might not be linked to bash, ksh, dash, ..., or a 1970's vintage pure Bourne shell depending on what operating system you are using at the time.

Of course, you can always use:

Code:

bash script_file

to have bash run script_file no matter what the first line of script_file looks like.