title: "&" in for loop in bash shell
body: <p>I am using &amp; to run multiple programs together in for-loop in bash shell script</p>
  <p>for example,</p>
  <pre><code>for ((i=1;i&lt;=45;i=i+1))
  do
      
      python pythonfile.py --gpu 4 --seed ${i} &amp;
      python pythonfile.py --gpu 4 --seed ${i} &amp;
      python pythonfile.py --gpu 5 --seed ${i} &amp;
      python pythonfile.py --gpu 5 --seed ${i} &amp;
      python pythonfile.py --gpu 6 --seed ${i} &amp;
      python pythonfile.py --gpu 6 --seed ${i} &amp;
      python pythonfile.py --gpu 3 --seed ${i} &amp;
      python pythonfile.py --gpu 3 --seed ${i} 
  
  
  done
  </code></pre>
  <p>and I did not put &amp; in that last sentence,
  because it would be terrible if I run &amp;... 45*8 programs together</p>
  <p>but It still runs more programs than 8 programs together.</p>
  <p><a href="https://i.stack.imgur.com/Cct0G.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Cct0G.png" alt="enter image description here" /></a></p>
  <p>Why this problem is happening?</p>