run lines of code only if user input greater than a number in bash script

bluethundr · 08-23-2018, 03:47 PM

In a bash script I want to run some lines of code only if a user input is greater than 1. I'm asking the user to tell us how many AWS servers they want to create.

If the number of servers is greater than one, the user inputs server names into an array. If the number is only 1 then it reads the server name into a variable.

Is this the right test to be performing?

Code:

    printf "Enter Number of Instances: "
    read -r num_instances
    if (( "$num_instances" > 1 )); then
      while [ "$num_instances" ]
       do
         printf "Enter a server name: "
         read -a server_names
         done
       else
          printf "Enter a server name: "
          read -r name_tag
       fi

berndbausch · 08-23-2018, 09:31 PM

Quote:

Originally Posted by bluethundr

Code:

    printf "Enter Number of Instances: "
    read -r num_instances
    if (( "$num_instances" > 1 )); then
      while [ "$num_instances" ]
       do
         printf "Enter a server name: "
         read -a server_names
       done
    else
          printf "Enter a server name: "
          read -r name_tag
    fi

You never count down num_instances, so that the while loop will run forever.

You may want to add code that checks if num_instances is really a number. Inside ((...)), you don't need the dollar or the quote characters; the code is prettier without them. Instead of [[...]], you can use ((...)), again without dollar or quotes.

Why do you distinguish between the two cases of a single server and more than one server? It seems to me that this makes your program overly complicated.