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bashshellparameter-expansion

Bash convert last character to lower

I'm trying to convert the last character of in a variable to lower.

MY_STRING="THE_NAME_UPPER_A"

I want to change it by THE_NAME_UPPER_a. I've try this

MY_NEW_STRING="${MY_STRING,,A}"

but it changes all A to a, I just want to change the last one.

Solution

  • If I understand you correctly you could use tr:

    ## Your string
MY_STRING="THE_NAME_UPPER_A"

## Everything but the last character
prefix="${MY_STRING:0:$((${#MY_STRING}-1))}"

## Getting the last character
lastChar="${MY_STRING: -1}"

## Change last character to lowercase
lastCharLow="$(echo "$lastChar" | tr '[:upper:]' '[:lower:]')"

## Combine it all and echo
echo "${prefix}${lastCharLow}"