I tried the following but without success
[root@OBAMA~]# bash
[root@OBAMA~]# a=HelloWorld
[root@OBAMA~]# [[ $a == [A-Za-z] ]] && echo "YES ITS STRING"
( the command not prints anything )
[root@OBAMA~]# [[ $a == [A-Z][a-z] ]] && echo "YES ITS STRING"
( the command not prints anything )
Change your command lke below.
$ [[ $a =~ [A-Za-z]+ ]] && echo "YES ITS STRING"
YES ITS STRING
Use =~ operator to test an input string against a regex.
Add + next to the character class, so that it would repeat the previous pattern or token one or more times. Here it's unnecessary.
Add anchors , in-order to do an exact string match. [[ $a =~ [A-Za-z] ]] && echo "YES ITS STRING" alone will print the string YES ITS STRING because the variable a contains atleast an alphabet.
$ a="HelloWorld"
$ [[ $a =~ ^[A-Za-z]+$ ]] && echo "YES ITS STRING"
YES ITS STRING
$ a="Hello World"
$ [[ $a =~ ^[A-Za-z]+$ ]] && echo "YES ITS STRING"
$
how do you define "a string"
[[ -n $a ]] && echo variable a is not empty
[[ $a == *[[:alpha:]]* ]] && echo variable a contains a letter
shopt -s extglob failglob
[[ $a == +([[:alpha:]]) ]] && echo variable a only has letters
Your glob expressions are not matching because your checking that your variable contains only 1 character or 2 characters.
