Shell Programming and Scripting

  input clock;
  input a; //reset all
  input [9:0] b;

  //input comment
  output c;
  output d;
  output [1:0] e;
  input   [4:0] f;
  //output comment

\\Inputs
clock
a
b
f[4:0]
\\Outputs
c
d
e[1:0]

gawk '\
  {
  gsub(/(^ *|^\t)/, "", $0) \\ for cutting one or more space OR tab
  if( match($0,/^input/) ){
          print $0 > "del1"
  }
  if( match($0,/^output/) ){
          print $0 > "del2"
  }
}' file

gawk ... file && cat del1 del2 >>final_output && rm -f del1 del2

gawk '\
  {
  gsub(/(^ *|^\t)/, "", $0) \\ for cutting one or more space OR tab
  }
  /^input/ {
          inputs[++in]=$0;
  }
  /^output/) {
          outputs[++out]=$0;
  }
  END { 
      print "Inputs:"
      for (x=0; x < in; ++x)
         print inputs[x];
      print "Outputs:"
      for (x=0; x < out; ++x)
         print outputs[x];
  }
}' file