The tr command translates one group of characters into another
set. This is often used to change uppercase to lowercase or
vice versa. The command does not accept a file name so its input must
be through the standard input. For example, to convert the capital
characters 'A' through 'Z' in file upper.f into 'a' through 'z'
in file lower.f:
% tr '[A-Z]' '[a-z]' < upper.f > lower.f % tr -s " " " " < paper.tex Remove multiple blank spaces.
In the second command we used the -s option to squeeze multiple occurrences of a character (in this case blanks) into a single occurrence of that character.