Getting user input during bash script

Question

I am trying to create my first bash script:

echo "What file are we looking for: "
read FILE

while [ 1 ]
do 
    ls -lah | grep $FILE
    sleep 1;
    clear
    
    # Some way to detect user input
    if [ user-input ]
       then
        echo "Input found"
        exit 1;

    fi

done

Is there a way to look for user input without pausing the program? When I used read input before the if statement, the program stopped until input was...inputted.... The program is supposed to continuously output the file I am look using ls and clear so I can monitor the size as it grows, but when the user inputs any key stroke the program exits.

Like I said this is my first bash script, I do know python pretty well and understand 'coding' but not bash.

Thanks

Answer 1

check Bash input without pausing the script?, seems like a duplicate. from that link:

read -t0 can be used to probe for input if your process is structured as a loop

 #!/bin/bash

 a='\|/-'
 spin()
 {
  sleep 0.3
  a="${a:1}${a:0:1}"
  echo -n $'\e'7$'\r'"${a:1:1}"$'\e'8
 }

 echo 'try these /|\- , dbpq , |)>)|(<( , =>-<'

 echo -n "  enter a pattern to spin:"
 while true
 do
   spin
   if read -t0 
   then
     read a
     echo -n "  using $a enter a new pattern:" 
   fi
 done

else you could run one command in the background while promptiong for input in the foreground. etc...