Linux Commands and Scripts

10 Useful tr commands in Linux

In this article, we will see information more about 10 useful tr commands in Linux.

tr (short for translate) is a useful command line utility that translate, squeeze, and/or delete characters from standard input, writing to standard output. It is a useful program for manipulating text on the command line.

The syntax of the tr command:

# tr [OPTION]… SET1 [SET2]

1 Convert all text in from lower case to upper case and vise versa

# cat file.txt | tr [:lower:] [:upper:]

It convert text from lower case to upper case.

2. The alternative command for above command is as shown below

# cat linux.txt | tr [a-z] [A-Z]

3. Input and output redirection

# tr [a-z] [A-Z] < file1.txt > file2.txt

Using this command you can send input to tr using the input redirection and redirect the output to a file using the same command.

4. Remove characters from file

# cat file.txt | tr -d ‘ ‘

Above command will remove white space from the file. You can mention any character that you want to remove.

5. Remove double characters

# cat domains.txt | tr -s ‘ ‘

Above command will remove double white spaces. You can use the -s option to squeeze the characters leaving only one occurrence of it.

6.  Display number from the file

# cat file.txt | tr -cd “[:digit:]\n”

If you want to display number and remove all letters, above command will help you. The -c option tells tr to use the complement in the given of SET.

7. Break line in to single word

# cat file.txt | tr ” ” “\n”

This command will break the single line of words into multiple lines.

8. Join multiple lines in one single sentence

# tr “\n” ” ” < file.txt

9. It is also possible to translate just a single character, for instance a space into a “ : ” character, as follows.

# echo “ =>Linux-HowTos,Guides,Tutorials” | tr ” ” “:”

10. Man page

# man tr

To learn more about tr run above command.

In this article, we have seen 10 useful tr commands in Linux.

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