When input “153”, the shell script will identify and display “1”, “5” and “3” on the screen sequentially. If input “69”, it will display “6” and “9”.

CodePudding user response：

Pipe user input through sed:

echo $1 | sed 's/\(.\)/\1 /g'

CodePudding user response：

Bash treats everything as a string.

Here is a Bash way to loop character by character over a string:

s=123
for (( i=0; i<${#s}; i   )); do
    echo "${s:$i:1}"
done

Prints:

1
2
3

Still for you to do:

1. Determine that s is a valid integer (Hint)
2. Determine that s is a string representing less than 10,000? (Hint: inside of (( double_parentesis )) Bash treats those strings as integers)

CodePudding user response：

Does your grep support the -o option? Then

$ echo "153" | grep -o .
1
5
3