Why does this while loop not execute after the first loop?

Question

I need a script to make a screenshot every x seconds. In the code I'm using touch for simplicity.

When I run the code the first touch(screenshot 1) is run and a file is created. But after waiting 5 seconds it echo for screenshot 2 but touch isn't run. Because no file is created. I have no idea why this would be te case.

#!/usr/bin/env bash
file=$(date +%Y-%m-%d.%H:%M:%S)    
x=1    
while true
do    
  echo "screenshot $x"    
  touch $file.jpg    
  sleep 1      
  x=$[$x+1]    
done

Won't this just create the same file over and over and over and over again? No matter how many times it loops it's still just going to create the same file... — JNevill
– JNevill, Commented Jul 2, 2019 at 19:44
This runs just fine for me. Are you 100% sure this is exactly the code you're running? — Kevin M Granger
– Kevin M Granger, Commented Jul 2, 2019 at 20:25

Ben Van Camp · Accepted Answer · 2019-07-02 19:44:25Z

5

You should re-assign ${file} every time the loop runs! You're assigning it outside the loop, so you're touching the same filename every time!

x=1

while true; do
  # Assign a new name (with a new timestamp) to $file, and a file
  # with a new name will be created!
  file=$(date +%Y-%m-%d.%H:%M:%S)

  echo "screenshot $x"

  touch $file.jpg

  sleep 1

  x=$(( x + 1 ))

done

Note: Your touch command WAS working, it was just applying the same filename. Hope this helps!

answered Jul 2, 2019 at 19:44

Ben Van Camp

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2 Comments

user11731017 Over a year ago

Thank you! This works. Very logical if you think about it.

Ben Van Camp Over a year ago

No problem bigyu!

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