Landoflinux

In the following example we use the "tr" command to translate text that is keyed in. Any letter entered in lowercase will be translated to upper case.

$ tr abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ
welcome to the land of linux
WELCOME TO THE LAND OF LINUX

An easier way to translate between "upper" and "lower" case characters is to use the "[:lower:]" and "[:upper:]" options.

$ echo 'welcome to the land of linux' | tr "[:lower:]" "[:upper:]"
WELCOME TO THE LAND OF LINUX

A popular method for achieving the same result can be achieved by specify a range of characters: "a-z" and "A-Z". In the following example the text "welcome to the land of linux" will be translated to upper case characters.

$ echo 'welcome to the land of linux' | tr "a-z" "A-Z"
WELCOME TO THE LAND OF LINUX

Translating the contents of a file

In the following example we have used a file called "test.txt". The contents of the file are displayed below.

$ cat test.txt
start[]
middle[]
end[]

Here we read in the contents of our text file using redirection, then we write the translated version of the file to a new file called "newfile.txt".

$ tr '[]' '()' < test.txt > newfile.txt

$ cat newfile.txt
start()
middle()
end()

Deleting Specified Characters

The "-d" parameter can be used to delete characters.

$ echo "This is another test" | tr -d 'a'
This is nother test

In the above example the character "a" was removed.

Deleting New Line Characters

The following file will be used as an example.

$ cat test2.txt
Line one
Line two
Line three
Line four
Line Five

The "-d" option is used to specify the "tr" command to delete a character. A common use for the "tr" command is to remove "new line" characters from a file. The new line character is specified as "\n".

$ cat test2.txt | tr -d "\n"
Line oneLine twoLine threeLine fourLine Five

Interpreted Sequences

As well as the "-n" option. You can also specify any of the following values:

       \NNN   character with octal value NNN (1 to 3 octal digits)

       \\     backslash

       \a     audible BEL

       \b     backspace

       \f     form feed

       \n     new line

       \r     return

       \t     horizontal tab

       \v     vertical tab

Translate new lines to a single space

$ tr -s '\n' ' ' < test2.txt
Line one Line two Line three Line four Line Five 

White Space to Tabs

$ echo "This is a test" | tr [:space:] '\t'
This    is      a       test

White Space to NewLine

$ echo "This is a test" | tr [:space:] '\n'
This
is
a
test

Removing Spaces

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

tr Options

       -c, -C, --complement
              use the complement of SET1

       -d, --delete
              delete characters in SET1, do not translate

       -s, --squeeze-repeats
              replace each input sequence of  a  repeated  character  that  is
              listed in SET1 with a single occurrence of that character

       -t, --truncate-set1
              first truncate SET1 to length of SET2

       --help display this help and exit