-3

  1. What is the purpose of running a command with eval?

  2. What kinds of commands can eval run? I find it can run builtin command, external executable command, pipeline, script. Can it run all kinds of commands which can be run in a shell directly?

  3. Compare running a command directly in a shell and indirectly via eval. Is the difference only in that with eval the command will be parsed twice instead of just once?

  4. Compare running a command via eval and via command. Assume that the command can be run by both. What differences are between the two ways?

Community
  • 1
Tim
  • 101,790
  • link to http://unix.stackexchange.com/questions/278427/why-and-when-should-eval-use-be-avoided-in-shell-scripts – Tim Apr 22 '16 at 22:54

1 Answers1

2

After the Command-line has been expanded:

eval sends back the arguments to the first step of "Command-Line Processing".

All steps of Command-Line Processing are presented in this page.