Question

#!/bin/sh
var="$1";
OUTPUT=$(echo ${$var,,});
echo $OUTPUT

I tried every possible combination, including escaping certain characters.

I just cant get shell to output my script argument lower cased.

Error:

createmodule.sh: 26: createmodule.sh: Bad substitution

Why is this?

Answer 1

There’s a mistake, try this instead :

#!/bin/bash
var="$1"
OUTPUT=${var,,}
echo $OUTPUT

You have had a $ in excess.

As seen in discussion, never call scripts with sh script if you are not sure that the wanted shell is really a sh one. A better approach is to put the good shebang like #!/bin/bash, and then chmod+x script.sh and finally ./script.sh