grep -v '#'

grep -v '^#'

$ cat ./testscript.sh
#!/bin/bash

# comment
set -vn
echo "Hello World" # another comment
$ ./testscript.sh
echo "Hello World" # another comment

gcc -fpreprocessed -dD -E test.c

import tokenize
import io
import sys

def nocomment(s):
    result = []
    g = tokenize.generate_tokens(io.BytesIO(s).readline)
    for toknum, tokval, _, _, _  in g:
        # print(toknum,tokval)
        if toknum != tokenize.COMMENT:
            result.append((toknum, tokval))
    return tokenize.untokenize(result)

print(nocomment(sys.stdin.read()))

#!/bin/sh
case "$1" in
  *.py)
    remove-comments.py < "$1"
    break
    ;;
  *.c|*.C|*.cc)
    gcc -fpreprocessed -dD -E "$1"
    break
    ;;
  *)
    echo I do not know how to remove comments from $1, sorry
    break
    ;;
esac