More useful shell tricks for bash. These are very useful tricks for any Linux user.

Posted: April 21, 2014. At: 9:29 PM. This was 4 years ago. Post ID: 7180
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This sed trick will filter out the unwanted characters and leave only the letters ‘A’.

homer@deusexmachina ~ $ echo "###AAA" | sed 's/###//gi'

This is how to re-bind the annoying CAPS-Lock key to Esc. This can give that key a new use.

xmodmap -e 'clear Lock' -e 'keycode 0x42 = Escape' &

Here is how to print the architecture of your Linux installation.

homer@deusexmachina ~ $ dpkg --print-architecture

How to test disk writing speed with the Linux command line.

homer@deusexmachina ~ $ dd if=/dev/zero of=/tmp/output.img bs=8k count=256k conv=fdatasync; rm -rf /tmp/output.img
262144+0 records in
262144+0 records out
2147483648 bytes (2.1 GB) copied, 19.4116 s, 111 MB/s

Generate a random password using /dev/urandom.

homer@deusexmachina ~ $ LANG=c < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-16};echo;

Show all tcp4 listening ports.

homer@deusexmachina ~ $ netstat -lnt4 | awk '{print $4}' | cut -f2 -d: | grep -o '[0-9]*'

Get information about your user.

homer@deusexmachina ~ $ finger homer
Login: homer          			Name: John Cartwright
Directory: /home/homer              	Shell: /bin/bash
On since Mon Apr 21 14:14 (EST) on tty8 from :0
    7 hours 13 minutes idle
On since Mon Apr 21 18:48 (EST) on pts/0 from :0.0
No mail.
DOS: n., A small annoying boot virus that causes random spontaneous system
     crashes, usually just before saving a massive project.  Easily cured by
     UNIX.  See also MS-DOS, IBM-DOS, DR-DOS.

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