tr

• The tr command accepts input from standard input
• This command takes two arguments which specify two character sets
• The first character set is replaced by the equivalent member in the second character set
• the -s option is used to squeeze several occurrences of a character to one character

Syntax

tr [-Ccsu] string1 string2 

option	description
-C	Complement the set of characters in string1, that is "-C ab" includes every character except for 'a' and 'b'.
-c	Same as -C but complement the set of values in string1.
-d	Delete characters in string1 from the input.
-s	Squeeze multiple occurrences of the characters listed in the last operand (either string1 or string2) in the input into a single instance of the character. This occurs after all deletion and translation is completed.
-u	Guarantee that any output is unbuffered.

Examples -tr -cs "[:alpha:]" "\n" < file1

Create a list of the words in file1, one per line, where a word is taken to be a maximal string of letters.

• tr "[:lower:]" "[:upper:]" < file1

Translate the contents of file1 to uppercase.

• tr -cd "[:print:]" < file1

Remove all non-printable characters from file1.

• tr -s " " < file1

to remove all empty spaces