title: set: Variable name must begin with a letter
body: <p>Its my code, how to set k as 17 less than j.
  It gives the error:
  set: Variable name must begin with a letter.</p>
  
  <pre><code>#! /bin/csh -ef
  
      set j =  18
      while ($j &lt;= 40)
      set k = $j-17
      set i = 18
      while ($i &lt;= 40)
      set l = $i - 17
          echo $i $j|gmx mindist -f 10ns_bit_45deg_LC3-v2.xtc -s for_prod2_POPC_24LC3-45deg.tpr -n LC3_protein_index.ndx -xvg none -od distance_p$l-LC3p$k.xvg -o distance_p$l-LC3p$k.out
      #   echo 17 14|g_dist -f ../../combined_trr/comb_10micro_LC3_310_1136lipids_MDSIM$j.trr -s ../cgmdsim1_1mer_LC3_310K_1136lipids.tpr -n GLP_a286.ndx -xvg none -o dist_protein_POPC_traj$j.xvg 
      #   awk ' { print $1, $5 }' dist_glp_protein_POPC_traj$j.xvg &gt;zaxisdist_glp_protein_POPC_traj$ju.xvg
  
  @ j++
  @ i++
  
      end
  
  exit -1
  </code></pre>