Linux

Disk Usage

du -S | sort -g -r | less
du -s -k *

Find

find . -name \*.swp -exec rm \{\} \; # delete matches
find . -mtime -30 # modified in last 30 days

Grep

• -l - filenames only
• -n - line numbers
• -R - recursive

DNS

host hostname: IP address, mx
host -a hostname: "all"
host -t txt hostname: txt records

Network Traffic

tcpdump 'tcp port 25' # outgoing smtp
tcpdump 'host supernifty.com.au and port 80'

• -A: traffic in ascii
• -s 0: show full packet
• -i eth0: interface to listen on
• -l: don't buffer output

SSH Tunnels

• A tunnel listening on the local machine

ssh -L localport:remotehost:remoteport

• A tunnel listening on the remote machine

ssh -R remoteport:localhost:localport

• SOCKS proxy

ssh -D port

e.g.

ssh -D 1080 user@host

I needed FoxyProxy to have this work on Firefox.

Top

• M - sort by memory usage
• P - sort by CPU