${a,}: bad substitution

var=hello #For Bash Version higher than 4.3.33 try these
echo ${var''} #Uppercase whole string
HELLO
echo ${var'} #Uppercase only first char of string
Hello
var2=BYE
echo ${var2,} #Lowercase whole string
bye
echo ${var2,,} #Lowercase only first char of string
bYE
echo $var | tr 'a-z' 'A-Z' #For lower versions of Bash just use tr command
HELLO

Similar codes

6 votes141 views2 answers
Apache start stop restart
Shell/Bash
0 vote155 views1 answer
Download latest stable solc ubuntu
Shell/Bash
70 votes181 views6 answers
Install docker
Shell/Bash
0 vote203 views1 answer
Set wp-config.php using wp-cli
Shell/Bash
0 vote186 views1 answer
Bash yaml parser library
Shell/Bash
0 vote145 views1 answer
Bash copy contents of file to clipboard
Shell/Bash
1 vote145 views1 answer
Install sublime text manjaro
Shell/Bash
2 votes139 views1 answer
Merge master into feauture branch
Shell/Bash
1 vote153 views1 answer
How to know my ros version
Shell/Bash
1 vote133 views2 answers
Npm login command
Shell/Bash