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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

Buy it now, or read it online on Safari Bookshelf.


tac [options] [file]

Named for the common command cat, tac prints files in reverse to standard output. Without a filename or with -, it reads from standard input. By default, tac reverses the order of the lines, printing the last line first.


-b, --before

Print separator (by default a newline) before the string it delimits.

-r, --regex

Expect separator to be a regular expression.

-s string, --separator=string

Specify alternate separator (default is newline).


Print a help message and then exit.


Print version information and then exit.

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