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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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md5sum [option] [files] md5sum [option] --check [file]

Compute or check 128-bit MD5 checksums. Used to verify that no change has been made to a file. With no files or - specified, read from standard input. The exit status is 0 for success and nonzero for failure.


-b, --binary

Read the files in binary mode. The default on DOS or Windows.

-c, --check

Check the MD5 sum and file information in the file argument (or standard input) against the corresponding files and verify that they are consistent. The input must have been generated by an earlier md5sum command.


Print usage information and exit.


Don't generate output messages; the exit code indicates success or failure. Used only with --check.


Compute the MD5 sum for the specified string. This option does not take a file argument. Put quotes around the string if it contains spaces.

-t, --text

Read files in text mode. The default.


Print version information and exit.

-w, --warn

Warn about improperly formatted checksum lines. Used only with --check.

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