bash - How to check if the user has entered a single letter? -

i reading character , want check if single character , letter. code below:

#!/usr/bin/bash read -p "enter something: " char if [[ ${#char} != 1 && "$char" != *[a-z]* ]];     echo "not valid input" else     echo "its valid input" fi 

the o/p below:

[root@host-7 ~]# sh -x t + read -p 'enter something: ' char enter something: 1 + [[ 1 != 1 ]] + echo 'its valid input' valid input 

while executing script first condition getting executed , not checking second condition.

it not evaluating 2nd condition because first condition failing you're entering 1 character in input , there && between 2 conditions.

if enter 2 character input ab you'll see both conditions getting evaluated.

---

you can use -n1 restrict input 1 character this:

#!/usr/bin/bash  read -n1 -p "enter something: " char echo if [[ "$char" != *[a-z]* ]];then    echo "not valid input" else    echo "its valid input" fi 

and run as:

bash -x ./t