tr - Translate command in Unix

• The tr utility copies the given input to produced the output with substitution or deletion of selected characters. 
• It takes as parameters two sets of characters, and replaces occurrences of the characters in the first set with the corresponding elements from the other set 

Syntax : 

tr [options] "set1" "set2"
tr "set1" "set2" < input.txt
tr "set1" "set2" < input.txt > output.txt

Translate the word 'linux' to upper-case:


$ echo "linux"|tr "a-z" "A-Z"
LINUX

Remove all two more successive blank spaces from a copy of the text in a file called input.txt

tr -s ' ' ' ' < input.txt

To replace every sequence of one or more new lines with a single new line: 

tr -s '\n' < input.txt 

To replace every sequence of one or more new lines with a single new line and remove the consecutive spaces in the word.

tr -s '\n' < input.txt |tr -s ' ' ' '

Delete the special characters in a file

To remove the carriage return from the carriage return/newline pair used by Microsoft OSes as a line terminator 

tr -d '\r' < pc.file > unix.file 

To delete all NULL characters from a file:

tr -d '\0' < textfile > newfile 

To replace every sequence of characters in the <space> character class with a single : (colon) character, enter: 

tr -s '[:space:]' '[\:*]' < in_file