Recipe: Translate with tr

tr
==
$ echo "HELLO WHO IS THIS" | tr 'A-Z' 'a-z'


Crypts
======
$ echo  12345 | tr '0-9' '9876543210'
3365 #Encrypted

$ echo 3365 | tr '9876543210' '0-9'
12345 #Decrypted

Tab to space
============
$ cat text |  tr '\t' ' '

Complementing
=============

$ cat text | tr -d -c 'a-z'
# Removes all except lower-case alphabets from the input

Deleting characters from input
==============================
$ echo "Hello 123 world 456' | tr -d '0-9'
Hello  world

Squeeze repeated
================
$ echo "GNU is       not     UNIX. Recursive   right ?' | tr -s ' '
GNU is not UNIX. Recursive right ?
# tr -s '[set]'

tr sum hack
===========
$ cat sum.txt
1
2
3
4
5

$ cat sum.txt | echo $[ $(tr '\n' '+' ) 0 ]
15