title: Linux Shell Script execute without save to temporary variable
body: <p>If I want to execute a command with variables in it, I always have to store the string first in a variable and then can execute it...</p>
  
  <p>Example:</p>
  
  <pre><code>path_fasta="/home/xxx/yyy/zzz/qqq/"
  name_fasta="CTA_Mix_DNA.fna"
  path_outp"/some/Path/"
  
  temp='find . -maxdepth 1 -not -name '$name_fasta' -not -name letsgo.sh -delete'
  $temp
  
  temp=$path_mothur'mothur #set.dir(output='$path_outp');summary.seqs(fasta='$path_fasta''$name_fasta')'
  $temp
  </code></pre>
  
  <p>How do I do this directly <strong>without storing it first in temp</strong>? Must be easy, but did not find a solution...</p>