Usage of shebang in file header: is there any option to pass multiple arguments in shebang

I am using a different namespace for my python file execution. using a shebang/hashbang, to execute this script (/bin/bash -c ).

problem faced is shebang only accepts a single argument. even if i pass multiple args its treating it as a single string.

shebang used: #!/sbin/ip netns exec tmp <executable>

Experiment:

single executable using : #!/sbin/ip

Object " tmp" is unknown, try "ip help".

one arg shebang in tmp : #!/sbin/ip netns

$/bin/bash -c  tmp
Command "tmp" is unknown, try "ip netns help".

with two arg shebang used in tmp: #!/sbin/ip netns exec
```
$/bin/bash -c  tmp
Object "netns exec" is unknown, try "ip help".
```
- its picking "netns exec" as a single argument

full cmd used

shebang used in tmp : #!/sbin/ip netns exec global python

$/bin/bash -c  tmp
Object "netns exec global python" is unknown, try "ip help".

Is there any way to pass multiple argumenets to shebang executable other than chaining files.

Solution

Linux (and other OSs I believe) only split the shebang string once, at the first whitespace. So you can only ever pass one argument.

When you do #!/sbin/ip netns exec tmp <executable>, ip sees one argument string: netns exec tmp <executable> (including spaces).

But GNU env added the -S option for splitting shebang arguments. It's also available on FreeBSD env. But not busybox env.

So if you launch your interpreter using env -S:

#!/usr/bin/env -S command -a -b -c

env will split the three arguments on white space, and pass them to command. env of course is seeing the single argument -S command -a -b -c, but it can parse this.

I don't know enough about namespaces to know if this is a good idea, but it seemed to work for me:

$ sudo ip netns add test
$ sudo ip netns identify
# (empty)

$ cat /tmp/netns-shebang-test
#!/usr/bin/env -S ip netns exec test bash

echo "$BASH_VERSION"
echo "$0"
ip netns identify

$ sudo /tmp/netns-shebang-test
5.1.16(1)-release
/tmp/netns-shebang-test-script
test

I'm showing bash, but it also worked with a similar python script. I will repeat that I don't know enough about namespaces to know if this is a good approach or not.