Shell Builtin ‘eval’

You can use arrays.

    $ ls -la "foo bar"
    -rw------- 1 u0_a298 u0_a298 6 Jan 10 00:22 'foo bar'
    $ cmd=(cat "foo bar")
    $ "${cmd[@]}"
    hello

Edit, since someone pointed out you the article is using dash, something I overlooked, you can still avoid eval by using set to overload the script args:

    $ set -- cat "foo bar"
    $ "$@"
    hello

Not sure how this would work if you still need the values of the current args. I don't think there is a way set a variable to be the current "$@" to be used later. However, if you don't need the current args any more, this is a possible solution to avoid eval.

I recently had to use eval to solve a shell scripting problem.

During the same task, I also discovered that a for loop on it's own is run inside the same shell as the code around it (duh), but a for loop which is feeding a pipe is run in a subshell. This was a surprise, because I wanted to set some variables in the for loop, piping progress indications to the `dialog` program, and then use those variables afterwards. My variables kept disappearing after the for loop exited, but not when I removed the progress indications.

Shell sucks.

Challenge accepted :)

  $ echo lorem ipsum > "foo bar"
  $ cmd='cat "foo bar"'
  $ trap "$cmd" ERR;test;trap - ERR
  lorem ipsum