10 best linux command

1. Take a screenshot with a date command thrown in:
import -window root screenshot-$(date +%Y%m%d%k%M).png
2. Remind yourself(Replace 'your reminder here' and the time '18:15′):
echo "DISPLAY=$DISPLAY xmessage your reminder here" | at 18:15
3. Return to previous directory:
cd -
4. Encrypt your files (Don't forget the password!):
gpg -c file.txt
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5. Decrypt your files:
gpg file.txt.gpg
6. Auto complete with the Tab key:
cd longdirname[Tab]
7. Use wildcards:
cd longdir*
8. View your disk space:
df --block-size=1000M
9. Make a backup of your CD drive or other device: (Replace /dev/cdrom with the repective device name; type 'mount' to see these.)
gzip < /dev/cdrom > ~/backup.gz
10. And finally - use the pipes:
lsof -i| grep ESTABLISHED