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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.

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envsubst [options] [shell-format]

Substitutes environment variables in a shell string or script. When used with no options, copies stdin to stdout, replacing any environment variable string, such as $VARIABLE or ${VARIABLE}, with the appropriate environment variable value. So, "My editor is $EDITOR" would be converted to "My editor is /usr/bin/emacs." Specifying a shell format limits the substitutions to those variables referenced in the shell format.



Print help message and then exit.


Print version information and then exit.


Display the variables referenced in the shell format, and then exit.

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