sed one-liner to convert all uppercase to lowercase?

regex sed
magnetar picture magnetar · Dec 31, 2010 · Viewed 172.2k times · Source

I have a textfile in which some words are printed in ALL CAPS. I want to be able to just convert everything in the textfile to lowercase, using sed. That means that the first sentence would then read, 'i have a textfile in which some words are printed in all caps.'

Answer

magnetar picture magnetar · Jan 3, 2011

With tr:

# Converts upper to lower case 
$ tr '[:upper:]' '[:lower:]' < input.txt > output.txt

# Converts lower to upper case
$ tr '[:lower:]' '[:upper:]' < input.txt > output.txt

Or, sed on GNU (but not BSD or Mac as they don't support \L or \U):

# Converts upper to lower case
$ sed -e 's/\(.*\)/\L\1/' input.txt > output.txt

# Converts lower to upper case
$ sed -e 's/\(.*\)/\U\1/' input.txt > output.txt

Related questions

How to output only captured groups with sed?

Is there any way to tell sed to output only captured groups? For example given the input: This is a sample 123 text and some 987 numbers and pattern: /([\d]+)/ Could I get only 123 and 987 output in the way formatted by back …

Read More
How to replace a whole line with sed?

Suppose I have a file with lines aaa=bbb Now I would like to replace them with: aaa=xxx I can do that as follows: sed "s/aaa=bbb/aaa=xxx/g" Now I have a file with a few …

Read More
Non greedy (reluctant) regex matching in sed?

I'm trying to use sed to clean up lines of URLs to extract just the domain. So from: http://www.suepearson.co.uk/product/174/71/3816/ I want: http://www.suepearson.co.uk/ (either with or without the trailing slash, it doesn't …

Read More