In looking at this and related questions, I'm surprised that no one brought up using an explicit subshell. For bash, and other modern shells, you can execute a command line explicitly. In bash, it requires the -c option.
argumentString="-ir 'hello world'"
bash -c "grep $argumentString ."
Works exactly as original questioner desired. There are two restrictions to this technique:
- You can only use single quotes within the command or argument strings.
- Only exported environment variables will be available to the command
Also, this technique handles redirection and piping, and other shellisms work as well. You also can use bash internal commands as well as any other command that works at the command line, because you are essentially asking a subshell bash to interpret it directly as a command line. Here's a more complex example, a somewhat gratuitously complex ls -l variant.
cmd="prefix=`pwd` && ls | xargs -n 1 echo \'In $prefix:\'"
bash -c "$cmd"
I have built command processors both this way and with parameter arrays. Generally, this way is much easier to write and debug, and it's trivial to echo the command you are executing. OTOH, param arrays work nicely when you really do have abstract arrays of parameters, as opposed to just wanting a simple command variant.
