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10 Amazing and Mysterious Uses of (!) Symbol or Operator in Linux Commands

16/06/2016 Comments off

Linux-logo-without-version-number-banner-sized-348x196The '!' symbol or operator in Linux can be used as Logical Negation operator as well as to fetch commands from history with tweaks or to run previously run command with modification. All the commands below have been checked explicitly in bash Shell. Though I have not checked but a major of these won’t run in other shell. Here we go into the amazing and mysterious uses of '!' symbol or operator in Linux commands.

1. Run a command from history by command number.

You might not be aware of the fact that you can run a command from your history command (already/earlier executed commands). To get started first find the command number by running ‘history‘ command.

$ history

History shell command

Now run a command from history just by the number at which it appears, in the output of history. Say run a command that appears at number 1551 in the output of ‘history‘ command.

$ !1551

History by number

And, it runs the command (top command in the above case), that was listed at number 1551. This way to retrieving already executed command is very helpful specially in case of those commands which are long. You just need to call it using ![Number at which it appears in the output of history command].

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