Unix/Linux

gistfile1.txt

Use ssh-copy-id to install your public key in a remote machine's authorized_keys. Also takes care of the permissions of the remote user's .ssh and .ssh/authorized_keys.

ssh -t reachable_host ssh unreachable_host. Enables to connect to a host unreachable from current network but reachable from reachable_host's network.

To navigate to a directory, run a command and get back: (cd /to/dir && cmd_to_run)

To rip audio out of a video file: mplayer -ao pcm -vo null -vc dummy -dumpaudio -dumpfile <out_file> <in_file>

Rsync: rsync --recursive -avz -e "ssh -p 2020" user@machine:/path dest

awk '!x[$0]++' filename => removes duplicates from the file without sorting.

update-rc.d -f service_name remove - removes a service from startup.

cat a b b | sort | uniq -u > c   # c is set difference a - b

http://vim.wikia.com/wiki/Switching_case_of_characters

# select 1000 random lines from a file
awk 'BEGIN { srand() } { l[NR]=$0 } END { for(i=1;i<=1000;i++){print l[int(rand() * NR + 1)]; } }' 2011.csv