Awk Rules Sample

  awk 'NF != 0 {++count} END {print count}' list

* Awk is useful for performing simple iterative computations for which a more sophisticated language like C might prove overkill. Consider the Fibonacci sequence:

   1 1 2 3 5 8 13 21 34 ... 

 
   awk 'BEGIN {a=1;b=1; while(++x<=10){print a; t=a;a=a+b;b=t}; exit}'

This generates the following output data:

   1
   2
   3
   5
   8
   13
   21
   34
   55
   89 

* Sometimes an Awk program needs to be used repeatedly. In that case, it's simple to execute the Awk program from a shell script. For example, consider an Awk script to print each word in a file on a separate line. This could be done with a script named "words" containing:

   awk '{c=split($0, s); for(n=1; n<=c; ++n) print s[n] }' $1 

The method for achieving this is also simple, and involves using a variable named "skip". This variable is set to "1" every time a blank line is skipped, to tell the Awk program not to skip the next one. The scheme is as follows:

   BEGIN {set skip to 0}
   scan the input:
      if skip == 0    if line is blank
                         skip = 1
                      else
                         print the line
                      get next line of input
      if skip == 1    print the line
                      skip = 0
                      get next line of input

This translates directly into the following Awk program:

   BEGIN      {skip = 0}
   skip == 0  {if (NF == 0) 
                {skip = 1} 
               else 
                {print}; 
               next}
   skip == 1  {print; 
               skip = 0;
               next}

My awk try :

 ls | gawk '{for(i=0;i<=NF;i++) {if(i==0) {print $i}}}'