Question

d is an internal server lookup tool I use.

I am looking to allow a user to input any number between 0 (or 1) and 9999 (let’s call this userinput) and have it display the result of:

d $userinput (e.g. 1234)

Then manipulate the results of that lookup (below gets rid of everything but the IP address to ping later):

 grep -E -o '(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)'`

I know I need to use the while true; do read $blah etc etc. I am just not familiar with read enough to format it properly and more importantly:

get it to prompt for a numerical input between 0-9999

Answer 1

<–edit–>

if all you want is the mechanic for prompting, try this:

echo -n "Enter server number:"
read userinput

then run validation checks on the input like this:

if [[ $userinput -lt 0 || $userinput -gt 9999 ]]   # checks that the input is within the desired range
 then
  echo "Input outside acceptable range."
else
  # insert your grep and ping stuff here
fi

<–end edit–>

on first read, i thought your problem sounded ideal for a wrapper script, so i was going to suggest this:

$ cat wrapper.sh
#!/usr/bin/bash

userinput=$1

if [[ $# != 1 ]]   # checks that number of inputs is exactly one
 then
  echo "Too many inputs."
  exit 2
elif [[ $userinput -lt 0 || $userinput -gt 9999 ]]   # checks that the input is within the desired range
 then
  echo "Input outside acceptable range."
  exit 3
fi

output=`d "$userinput"`

ping_address=`grep -E -o '(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)' <("$output")`

ping "$ping_address"

then call the script with like this:

$ wrapper.sh 1243