BASH: multiple ways to convert to/from lower/uppercase

 How to convert text files to all upper or lower case

How can you convert a text file to all lower case or all upper case?

As usual, in Linux, there are more than 1 way to accomplish a task.

To convert a file (input.txt) to all lower case (output.txt), choose any ONE of the following:


    dd

    $ dd if=input.txt of=output.txt conv=lcase


    tr

    $ tr '[:upper:]' '[:lower:]' < input.txt > output.txt


    awk

    $ awk '{ print tolower($0) }' input.txt > output.txt


    perl

    $ perl -pe '$_= lc($_)' input.txt > output.txt


    sed

    $ sed -e 's/\(.*\)/\L\1/' input.txt > output.txt


    We use the backreference \1 to refer to the entire line and the \L to convert to lower case.



To convert a file (input.txt) to all upper case (output.txt):


    dd

    $ dd if=input.txt of=output.txt conv=ucase


    tr

    $ tr '[:lower:]' '[:upper:]' < input.txt > output.txt


    awk

    $ awk '{ print toupper($0) }' input.txt > output.txt


    perl

    $ perl -pe '$_= uc($_)' input.txt > output.txt


    sed

    $ sed -e 's/\(.*\)/\U\1/' input.txt > output.txt