Just a list of 20 (now 28) tools for the command line. Some are little-known, some are just too useful to miss, some are pure obscure -- I hope you find something useful that you weren't aware of yet! Use your operating system's package manager to install most of them. (Thanks for the tips, everybody!)
dstat & sar
iostat, vmstat, ifstat and much more in one.
Visualizes network interface traffic over time.
vim & emacs
The real programmers' editors.
screen, dtach, tmux, byobu
Keep your terminal sessions alive.
See your log files in separate windows.
Presentation ("PowerPoint") tool for terminal.
xargs & parallel
Executes tasks from input (even multithread).
duplicity & rsyncrypto
Encrypting backup tools.
nethack & slash'em
Still the most complex game on the planet.
Does FTPS. Can mirror, kinda like rsync.
A better grep for source code.
calcurse & remind + wyrd
newsbeuter & rsstail
Command line RSS readers.
Helps conserve power on Linux.
A console UI for git.
The best calculator. Ever. (For scripts too.)
Discussion of this post on Hacker News - that's the place to get into nice old-school FidoNet-style flame wars about the important things in life, like whether or not tmux is better than screen , is parallel better than xargs , whether or not ifconfig is a power tool, or should this list include somebody's once-used tool for converting old Pascal code to C or something. :o)
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