CODEWITHSUNDEEP
classreplacesedcharacter
NCL
NCL

Reputation: 445

Uppercase to Lowercase with Sed and character classes

I'd like to convert a string from upper to lower case. I know there are different ways of solving this problem, but I'd like to understand why this command doesn't work:

echo "aa" | sed 's/'[:upper:]'/'[:lower:]'/g'

Is it a wrong way to use the classes of characters?

Upvotes: 2

Views: 2705

Answers (3)

Idriss Neumann
Idriss Neumann

Reputation: 3838

Another possible solution with gawk :

[ ~]$ echo "HELLO"|awk '{print tolower($0)}'
hello

Upvotes: 0

Yann Moisan
Yann Moisan

Reputation: 8281

from lowercase to uppercase, you can use

echo "aW123bR" | sed -r 's/[a-z]+/\U&/g'

tr command is an interesting alternative

echo "aW123bR" | tr '[:lower:]' '[:upper:]'

Upvotes: 6

Barmar
Barmar

Reputation: 782624

In sed, the y command is used for mapping sets of characters:

sed 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/'

It requires a literal list of characters, not character classes.

Upvotes: 1

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