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View non-printing characters with cat
Useful to detect number of tabs in an empty line, DOS newline (carriage return + newline). A tool that can help you understand why your parsing is not working.

perl one-liner to get the current week number
Not perl but shorter.

Make a file not writable / immutable by root
http://linuxhelp.blogspot.com/2005/11/make-your-files-immutable-which-even.html

Rename files in batch

My PS1
My PS1

Simplest port scanner
Very handy way to perform a host scan if you don't have nmap,ncat,nc ...or other tools installed locally. When executing a command on a /dev/tcp/$host/$port pseudo-device file, Bash opens a TCP connection to the associated socket and UDP connection when using /dev/udp/$host/$port.A simlpe way to get servers banner is to run this command "cat < /dev/tcp/localhost/25" , here you will get mail server's banner. NOTE: Bash, as packaged for Debian, does not support using the /dev/tcp and /dev/udp pseudo-device it's not enabled by default Because bash in Debian is compiled with ?disable-net-redirections.

Look for English words in /dev/urandom
Little faster alternative.

Remove multiple same rpm packages
If somehow if you get more than 1 same name rpm package install, then it cannot be removed by using simple rpm -e as it gives you more than one rpm matches error. The --matches will help to remove all the same name rpm packages.

killall -r ".*my-process.*"

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.


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