Two-Character Unix Commands

Here’s a fun survey question: name as many two-character Unix commands as you can and say what they do.

Let’s be precise about what we mean by a “command”:

  • Shell aliases like la are not commands.
  • Shell built-in commands count as commands; over time the shell incorporated directly things that were previously separate executables in Unix.
  • Commands not available in a wide variety of Unix distributions by default don’t count. In other words, if you have to install some optional package to get the command then it isn’t a “Unix” command.
  • Optional: Only allow commands included in a “classic” Unix from Bell Labs.

Ready? Let’s go.

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