LINUX COMMANDS

cat file | tr 'A-Z' 'a-z'                         Change uppercase to lowercase in a file

tr ' ' '\012' < file                              Turn spaces into newlines (ASCII code 012):

cat file | tr -s "" "\012" > new.file       Strip blank lines from file and save in new.file:

echo 'Test' | tr '[:lower:]' '[:upper:]'    Case conversion

tr '\0' '\n' < /proc/$$/environ             Display the startup environment for any process

$ diff -w file1 file2            Ignore white spaces

$ diff -q file1 file2             Just aswer if two files are different 

$ diff -y file1 file2             Show differences in columns