character case conversion Uppercase to Lower and vice versa

Question

I was trying to convert the lowercase characters to uppercase. I came across various alternatives like one listing at the StackOverflow question. However, What i saw that these are just printed. I want to save it to another variable which i can use later. Can anyone tell how i can achieve this?

nettux · Answer 1 · 2014-05-14T09:32:38.890

I know this is an oldish post but I made this answer for another site so I thought I'd post it up here:

here comes a programmers answer....

UPPER -> lower: use python:

b=`echo "print '$a'.lower()" | python`

Or Ruby:

b=`echo "print '$a'.downcase" | ruby`

Or Perl (probably my favorite):

b=`perl -e "print lc('$a');"`

Or PHP:

b=`php -r "print strtolower('$a');"`

Or Awk:

b=`echo "$a" | awk '{ print tolower($1) }'`

Or Sed:

b=`echo "$a" | sed 's/./\L&/g'`

Or Bash 4:

b=${a,,}

Or NodeJS if you have it:

b=`echo "console.log('$a'.toLowerCase());" | node`

You could also use dd (but I wouldn't!):

b=`echo "$a" | dd  conv=lcase 2> /dev/null`

lower -> UPPER:

use python:

b=`echo "print '$a'.upeer()" | python`

Or Ruby:

b=`echo "print '$a'.upcase" | ruby`

Or Perl (probably my favorite):

b=`perl -e "print uc('$a');"`

Or PHP:

b=`php -r "print strtoupper('$a');"`

Or Awk:

b=`echo "$a" | awk '{ print toupper($1) }'`

Or Sed:

b=`echo "$a" | sed 's/./\U&/g'`

Or Bash 4:

b=${a^^}

Or NodeJS if you have it:

b=`echo "console.log('$a'.toUpperCase());" | node`

You could also use dd (but I wouldn't!):

b=`echo "$a" | dd  conv=ucase 2> /dev/null`

Also when you say 'shell' I'm assuming you mean bash but if you can use zsh it's as easy as

b=$a:l

for lower case and

b=$a:u

for upper case.

how about capitalize the first letter on `zsh`, do you have any reference for these commands? @nettux — mochadwi, Dec 08 '19 at 16:02
@mochadwi You'd use `b=${(C)a}`. See the parameter expansion section from the zsh docs here: http://zsh.sourceforge.net/Doc/Release/Expansion.html#Parameter-Expansion-Flags — nettux, Dec 18 '19 at 15:40

score 7 · Accepted Answer · edited May 23 '17 at 12:10

7

Your input is $a. The new variable is $b.
(borrowed from here written by @ghostdog74)

using tr:

b=$( tr '[A-Z]' '[a-z]' <<< $a)

if you use tcsh, then use echo instead of <<<:

set b=`echo "$a" | tr '[A-Z]' '[a-z]'`

edited May 23 '17 at 12:10

Community

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answered Jan 25 '12 at 10:14

oHo

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1

You should post these as separated answers :) – khachik Jan 25 '12 at 10:23
Is that for tcsh? Consider the following as you mentioned gives error.
```
#! /bin/tcsh  
set a = "Helo World!"  
echo $a '<-'
set b = $(tr '[A-Z]' '[a-z]' <<< $a )  # error
echo 'a=' $a 'b=' $b  
```
The shell gives me error : "Illegal variable name." at line 4
– Abhinav Jan 25 '12 at 12:28
1

Hey @abhinav. I have fixed the `tcsh` version. I am sorry for the late, not so familiar with `tcsh`. Have fun ;-) – oHo Jan 25 '12 at 15:39
yea, having multiple separate answers (especially 1-liners) is discouraged. Best to have them all in one answer – SiegeX Jan 25 '12 at 17:11

score 4 · Answer 3 · answered Jan 25 '12 at 10:26

4

using bash 4.0:

b=${a,,}

answered Jan 25 '12 at 10:26

oHo

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this just awesome. – mochadwi Dec 08 '19 at 16:02

score 2 · Answer 4 · answered Jan 25 '12 at 10:26

2

using awk:

b=$( awk '{print tolower($0)}' <<< $a )

answered Jan 25 '12 at 10:26

oHo

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score 2 · Answer 5 · answered Jan 25 '12 at 10:26

2

using perl:

b=$( perl -e 'print lc <>;' <<< $a )

answered Jan 25 '12 at 10:26

oHo

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score 0 · Answer 6 · answered Feb 04 '16 at 19:16

0

All the previous answers are correct, I'm just adding this because there is no need to declare variable etc if you are simply converting texts.

echo changethistoupper | tr [a-z] [A-Z]
echo CHANGETHISTOLOWER | tr [A-Z] [a-z]

answered Feb 04 '16 at 19:16

grepit

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character case conversion Uppercase to Lower and vice versa

6 Answers6