Question

I have a bash code as follows

python "$TM"

The problem is that $TM can be whatever character, including ` characters. When $TM has `abc`, the bash tries to run abc as a command before giving it a parameter to python.

How can I prevent this? How can I pass the $TM literally without any interpretation?

ADDED

I need more explanation.

I’m using TextMate Bundle Editer so that the bash is called with a buffer ($TM_SELECTED_TEXT or $TM_CURRENT_LINE). The buffer is the selection I made in the TextMate editor. The bash code is as follows.

#!/bin/bash

if [ -n "$TM_SELECTED_TEXT" ]; then
    TM="$TM_SELECTED_TEXT"
else

if [ -n "$TM_CURRENT_LINE" ]; then
    TM="$TM_CURRENT_LINE"
fi

fi

/usr/bin/python /Users/smcho/smcho/works/prgtask/textmate/repeat.py "$TM"

The repeat.py is as follows

import sys

inputString = sys.stdin.read().decode('utf-8')
inputString = inputString.rstrip().lstrip()

content = inputString[0:-2]
mark = inputString[-1]

r_num = len(content)
string = "%s\n%s" % (content, mark * r_num)
sys.stdout.write(string)
sys.exit(0)

If the input is “abc:-“, it will convert the string to “abc\n—“.

The problem is that if the input contains “ character, bash evaluates it before sending it to python code as parameter.

Answer 1

I think you are getting it wrong. Bash didn’t “expand” TM because it contained backticks (that would be a terrible security breach), the variable already contains the output of the command. You should quote the backticks to prevent the process substitution to occur:

$ TM="`ls`"
$ echo $TM
file1 file2

vs:

$ TM="\`ls\`" # or TM='`ls`'
$ echo $TM
`ls`