tr command one liners

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tr is an UNIX utility for translating, or deleting, or squeezing repeated characters. It will read from STDIN and write to STDOUT. tr stands for translate.

The syntax of tr command is:

$ tr [OPTION] SET1 [SET2]

Translation

If both the SET1 and SET2 are specified and ‘-d’ OPTION is not specified, then tr command will replace each characters in SET1 with each character in same position in SET2.

1.       Convert lower case to upper case

# echo the | tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ

# echo the | tr [:lower:] [:upper:]

# echo the | tr a-z A-Z

2.       Translate braces into parenthesis

# tr '{}' '()' < inputfile > outputfile

3.       Translate white-space to tabs

# echo "This is for testing" | tr [:space:] '\t'

4.       Squeeze repetition of characters using -s

# echo "This   is   for testing" | tr [:space:] '\t'

# echo "This   is   for testing" | tr -s [:space:] '\t'

# echo "This  is  for testing" | tr -s [:space:] ' '

5.       Delete specified characters using -d option

# echo "the test string" | tr -d 't'

6.       To remove all the digits from the string, use

# echo "my username is samual007" | tr -d [:digit:]

7.       To remove all characters except digits, you can use the following.

# echo "my username is samual007" | tr -cd [:digit:]

8.       Remove all non-printable character from a file

# tr -cd [:print:] < file.txt

9.       Join all the lines in a file into a single line

# tr -s '\n' ' ' < file.txt

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