GNU/Linux Howtos

Linux and what you can do with it, including hosting, applications, and Raspberry Pi

Command Line Fu - Repository of useful commands
Linux Documentation - Categorized howtos and man pages
nixCraft - Linux tutorials
SS65 - Command line reference
Gitignore - Tool for creating gitignore files
Crontab Guru - Tool for editing cron schedule expressions
RegExr - Tool for for building regular expressions
Epoch Converter - Tool for converting epochs
The Linux Documentation Project - The goal of the Linux Documentation Project (LDP) is to create and distribute a canonical set of high quality free GNU/Linux documentation.
Advanced Bash Scripting