Shell Scripting: Expert Recipes for Linux, Bash, and More

History

The history command lists what commands have been run before, either in the current shell session or in others (by the same user). It generally stores this information in the .<shellname>_history file in the user’s home directory. This can be useful for auditing and for checking on what commands have been run, but it is not a security feature; the file is plain text and can easily be edited by anybody with permission to access the file.

Recalling Commands

You can recall commands in a number of ways; the standard, most basic way is to run the history command. That displays the commands stored in the current history buffer, with a number to the left of each one:

$ history | tail -7
  557  pwd
  558  cd
  559  cd bin
  560  ls
  561  cat dos2unix
  562  id
  563  history
$

These can be recalled with the bang, or pling, or exclamation mark (!) symbol, so typing !562 executes the id program again. Alternatively, !-n recalls the last-but-n command, so from this starting point, !-1 (or its shortcut, !!) would call history again, !-2 would call id, and !-3 would call cat dos2unix.

Searching History

There are three main ways to interactively search through the history buffer. The first is with the arrow keys; press the up arrow to scroll backwards and the down arrow to scroll forwards. When you get to a command you want to execute again, either press Enter to execute it exactly as before, or press the left or right arrows to start editing the command before re-executing it. ...