How does one execute a script that has been piped in?

Question

Starting with the execution context so that the problem makes sense:

I am running scripts written in Windows Subsystem for Linux. In this context, scripts written can sometimes accumulate carriage return characters in addition to newline characters (\r\n).

This is often unpredictable -- it is probably my mistake, but I am not interested in learning how not to make that mistake -- so I would like to have a robust way to execute scripts with carriage return characters.

What I have come up with so far is bumping up against a security layer:

<(sed 's/\r//g' script.sh)

bash: /dev/fd/63: Permission denied

In this case, I have not made the file socket (or whatever it is under the hood) executable.

---

bash <(sed 's/\r//g' script.sh) # works
bash <(sed 's/\r//g' foo.py) # ignores foo's hash-bang and fails

The second option fails because the hash-bang at the top of the python file has been ignored or I missed some call step.

---

A (temporary) option is:

python3 <(sed 's/\r//g' script.py)

However, this is problematic due to the versioning of the python binary (python<version#>), which is best handled at the #! ... line internal to the script.

Also, it will fail for the ecosystem of other hash-bangables -- I'll have to be specific everywhere, which is sort of a big bump in the snarliness of my little bite-sized scripts.

---

Is there a way to make this executable, not ignore the hash-bang, or a way to solve the overall problem differently?

Answer 1

Fix the broken file pre-emptively before executing it:

#!/bin/bash
dos2unix script.py
./script.py

For interactive use, use a wrapper script to fix the file before executing it. Create a file name run_broken_file.sh with the following content:

#!/bin/bash
dos2unix "$1"
"$@" 

And then you can run ./run_broken_file.sh ./script.py arg1 arg2 arg3

Sample run:

$ unix2dos script.py 
unix2dos: converting file script.py to DOS format...

$ ./script.py 
/usr/bin/env: ‘python3\r’: No such file or directory

$ cat -A script.py 
#!/usr/bin/env python3^M$
import sys^M$
print(f"hello {sys.argv}")^M$

$ cat run_broken_file.sh 
#!/bin/bash
dos2unix "$1"
"$@"

$ ./run_broken_file.sh ./script.py arg1 arg2 'arg3 with spaces'
dos2unix: converting file ./script.py to Unix format...
hello ['./script.py', 'arg1', 'arg2', 'arg3 with spaces']