I want to output a string by adding random integer to a variable to create the string. Bash however, just adds the numbers together.
#!/bin/bash
b=""
for ((x=1; x<=3; x++))
do
number=$RANDOM
let number%=9
let b+=$number
done
echo ${b}
Say every random number is 1, the script will output 3 instead of 111. How do I achieve the desired result of 111?
There are several possibilities to achieve your desired behavior. Let's first examine what you've done:
let b+=$number
Running help let:
let: let ARGUMENT...
Evaluate arithmetic expressions.
That explains why let b+=$number performs an integer addition (1, 2, 3) of $number to b instead of string concatenation.
Simply remove let and the desired behavior 1, 11, 111 will occur.
The other method to perform string concatenation:
b="$b$number"
Yes, simply "let b become the result of concatenating b and number.
As a side note, b="" is equivalent to b= as "" is expanded to an empty string. Module operation on a variable can be done with arithmetic expansion: number=$((RANDOM%9)).
((number = RANDOM % 9))