Tuesday, April 1, 2014

Convert a text file to all lower case or all upper case

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

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

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

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