Книга: Fedora™ Unleashed, 2008 edition

An Example of Conversions in Action

An Example of Conversions in Action

Crafting complex conversion entries is a task perhaps best left to the Linux/Unix expert, but the sample ftpconversions file included with wu-ftpd provides more than enough examples for the average Red Hat administrator. Building your own simple conversion entry is not really too difficult, so let's examine and decode an example:

:.Z: : :/bin/compress -d -c %s:T_REG|T_ASCII:O_UNCOMPRESS:UNCOMPRESS

In this example, the strip prefix (field 1) is null because it is not yet implemented, so this rule does not apply to prefixes. The second field of this rule contains the .Z postfix; therefore it deals with files that have been compressed with the compress utility. The rule does not address the add-on prefix or postfix, so fields 3 and 4 are null. Field 5, the external command field, tells the server to run the compress utility to decompress all files that have the .Z extension, as the -d parameter signifies. The -c options tells compress to write its output to standard out, which is the server in this case. The %s is the name of the file against which the rule was applied. Field 6 specifies that this file is a regular file in ASCII format. Field 7, the options field, tells the server that this command uncompresses the file. Finally, the last field is a comment that gives the administrator a quick decode of what the conversion rule is doing — that is, uncompressing the file.

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