Shell Programming and Scripting

Hello -- I am trying to learn to do a little sed and awk scripting to search for text and numbers in text files (text processing/manipulation). My professor gave me a piece of uncommented code and I am very unfamiliar w/ the language. Can someone help me with comments so I can understand what is happening in each line? I have cygwin running to run scripts.

thanks

Code:

BEGIN {ifreq=0; iint=0; ithresh=0.5; maxint=0.0}

/Wavenum|Frequencies/ {
  for (i=3; i<=NF; i++) {
    if ($i<freqs[ifreq-1] && ifreq>0) exit;
    freqs[ifreq]=$i;
    ifreq++;
  }
}
/Inten/ {  for (i=4; i<=NF; i++) {
    ints[iint]=$i;
    if (ints[iint]>maxint) maxint=ints[iint];
    iint++;
  }
}

END {
  if (ifreq!=iint) {
    print "Error: no. of Freqs doesn't match no. of ints.";
    print "No. freqs = " ifreq "  No. ints = " iint;
    exit;
  }
  delta=0.001;

  for (i=0; i<ifreq; i++) {
    iscale=ints[i]/maxint;
      print freqs[i], ints[i], iscale;
  }
}

Moderator's Comments:

please use code tags

It looks like some kind of frequency distribution/report.

What does the input data look like? Please provide a sample.

Attached is the frequency calculation section of an output file. The 1st section looks for a stationary point in the calculations (lowest energy state), so this code ignores that section. After the stationary point is found, the program runs through calculations for the frequencies and intensities corresponding to that stationary point structure along with some other information (population analyses,etc), so the file is a little long due to all of the other calculations completed along with frequencies, but a quick word search of the file with "frequencies" gets to the pertinent information for this code.