Red Hat Enterprise Linux Documentation
Apache HTTP Server Documentation
PostgreSQL Documentation
MySQL Documentation
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Linux Kernel Documentation
The Second Extended File System
Ext2 - OSDev Wiki
Ext4 (and Ext2/Ext3) Wiki
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SelfHTML HTML Tutorial und Referenz
Vimdoc the online source for Vim documentation
Vim Tips Wiki
Debian Wiki
PostgreSQL Wiki
Perl DateTime Wiki FAQ
Perl DBI
Advanced Bash-Scripting Guide An in-depth exploration of the art of shell scripting