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Convert camelCase to underscores (camel_case)

Terminal - Convert camelCase to underscores (camel_case)
sed -r 's/([a-z]+)([A-Z][a-z]+)/\1_\l\2/g' file.txt
2009-04-28 22:44:45
User: atoponce
Functions: sed
9
Up
Down
Convert camelCase to underscores (camel_case)

Useful for switching over someone else's coding style who uses camelCase notation to your style using all lowercase with underscores.

Show sample output | Add to favourites | Report as malicious

Know a better way?

If you can do better, submit your command here.

What others think

A great one. Thanks.

You missed the underscore though, this should be:

sed -r 's/([a-z]+)([A-Z][a-z]+)/\1_\l\2/g' file.txt

Comment by AmirWatad 44 weeks and 6 days ago

Fixed. I had it in the sample output, but must have missed it in the command itself. Thanks.

Comment by atoponce 44 weeks and 6 days ago

Good job

Comment by kaedenn 44 weeks and 6 days ago

Where's the reverse? :-)

Comment by furicle 44 weeks and 6 days ago

btw, it's good for names like camelCase, but not for camelCaseLong

:)

Comment by AmirWatad 44 weeks and 6 days ago

I think this is a little more robust:

It converts CamelCaseWord or camelCaseWord to camel_case_word (the last pipe is needed to handle the CamelCaseWord case)

sed 's/\([A-Z]\)/_\l\1/g' file.txt | sed 's/^_\([a-z]\)/\1/g'

Comment by AmirWatad 44 weeks and 6 days ago

and this is the reverse:

camel_case_word to camelCaseWord:

sed 's/_\([a-z]\)/\u\1/g' file.txt

camel_case_word to CamelCaseWord

sed 's/_\([a-z]\)/\u\1/g' file.txt | sed 's/^\([a-z]\)/\u\1/g'

Comment by AmirWatad 44 weeks and 6 days ago

Your point of view

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