awk and sed.

16th March, 2006     Linux,

Another of my subjects this semester at uni, had me using a bit of awk and sed this week just gone, and I must say, that I now do have a more understanding knowledge of both of these tools.

Before I did understand how to do rather small things with each (like change instances of words, to another word, and pull out every 4th word from a sentence to use elsewhere), I never did try and go any more into either of them.

As you can see from the following code snippets, I think I have dug a bit more into these tools.

sed: Change the order, of the first two parameters called by a function

s/somefunc((.*),(.*)(,.*))/somefunc(2,13)/g

awk: add line numbers to each line of a source file, without skipping numbers. Comments should not be numbered.

   { if ($1 ~////) { printf("%5st%sn", "", $0); next } }
   { if ($1 ~//*/) { z = 1; printf("%5st%sn", "", $0); next } }
   { if ($1 ~/*//) { z = 0; printf("%5st%sn", "", $0); next } }
   { if (z > 0) { printf("%5st%sn", "", $0); next } }
   { printf("%5st%sn", (NF? ++a ":" :""), $0) }
   

A sample output for this awk script would be:

      1:   #include 

    // main routine
   2:   int main(int argc, char argv[])
   3:   {
                / Incredibly complex function here --
                    * it prints hello world
                    */
      4:           printf("%s", "Hello, world");
      5:           return 0; // return zero!
      6:   }
   

And comparing what I did, to some other features of these tools, this is still only the beginning of their abilities.