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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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makemap [options] type name

System administration command. Create database maps for use by sendmail in keyed map lookups. makemap will read from standard input and create a database file of type type with filename name.db. If the TrustedUser option is set in /etc/ and makemap is invoked as root, the ouput file will be owned by TrustedUser.

Input should be formatted as:

key value

Comment lines with #. Indicate parameter substitution with %n. Specify a literal % character by entering it twice: %%. The type may be btree or hash.


-c size

Specify hash or B-Tree cache size.

-C file

Look up TrustedUser in the specified sendmail configuration file.


Allow duplicate entries. Valid only with btree type maps.

-D x

Treat x as the comment marker instead of #.


Allow empty value data fields.


Suppress conversion of uppercase to lowercase.


List supported map types.


Append the zero-byte string terminator specified in sendmail's configuration file to mapped entries.


Append to existing file instead of replacing it.


If some keys already exist, replace them. (By default, makemap will exit when encountering a duplicated key.)


Ignore safety checks.

-t delimiter

Use delimiter instead of whitespace.


Undo a map: print out the specified database file, one entry per line.


Verbose mode.

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