Parsing data with ruby (Page 1 of 2)

If your priority is to learn Ruby,  that's one answer,  if you just want to get it done with as little effort as possible,  I'd use awk and call awk from ruby.

If you want to learn more about Ruby, if you google

Ruby Awk

You'll find several examples of people who have done things in pure Ruby that they formally had done with AWK,  it should provide you with lots of examples.

OK, if you are that new to programming,  forget AWK,  it's just another learning curve you don't need right now.

First thing is to write a ruby program opens a file, reads each line, the just write that line back out.

file = File.new("crontab.out", "r")
while (line = file.gets)
    puts line
end
file.close

Get that to work and let me know

No you have it right,  I left off two of the array elements, thinking you could fill in the ... with the appropriate code,  an exercise left to the reader :>

Let's clean it up so it's complete and easier to read:

file = File.new("crontab.out", "r")
while (line = file.gets)
    parts = line.split(' ')
    puts "min = #{parts[0]}, hour = #{parts[1]}, day of month = #{parts[2]}, month = #{parts[3]}, day of week = #{parts[4]}"
end
file.close

Last edited by BradHodges (2011-11-08 19:45:20)

Not a problem,  in my last post there was a minor syntax error,  I've since corrected the post,  but see if you can figure it out first befor you look at the corrected post.

To explain what's ging on,  the split function of a string will split the string into an array based on the argument,  so

line.split(' ')

will split the String 'line' on the space character,

parts = "1 2 3 4 5".split(' ')

will return an array, (zero based index),  so after that call:

parts[0] = "1"
parts[1] = "2"
parts[2] = "3"
...

parts = "1,2,3,4,5".split(',')

would produce the same result

OK, now it get's tricky,  each part can have several formats

*
*/x  where x is a number
x,y,z...   where x or y or z or ??? are numbers
x-y  where x and y  are numbers

* means do nothing based on the position,  so if parts[0] = "*',  the cronjob is not based on minutes

*/2 means repeat,  so if parts[1] = "*/4", it means every four hours

x,y,z means each,  so if parts[4] = "0,2,5" it means every Sunday, Tuesday and Friday

x-y means all in the range,  so if parts[1] = "8-18", it means every hour from 8 AM to 6 PM

Do you want to decode and present all of that detail?

Yeah, this is the hard part. The only thing I want to achieve with this script is to have it output a Y if there is anything but a * in that column. If there's a *, it should just be a N.

I want to do this with multiple files simultaneously, as well. The times will vary on each of the servers, but the actual cron job itself and the appropriate columns should be the same (for example, said cron job will always execute at the interval of 10,25,40,55 * * * * except the 10,25,40,55 columns will all be different).

To make this simple, without needing to input specific times, and because getting more complicated than this would probably be over my head, just outputting a Y or a N for an entry in the results is sufficient for my purposes here.

Thanks! I need a bit of a brain break, but I'll tackle it later tonight or tomorrow and let you know. I really appreciate all your help so far with this project. I realize you're doing the vast majority of the work, so once this is over and done with I'm going to try and code something on my own to apply all that I've learned.

Yeah, that's the idea. Say I have 10 servers with the raw crontab output in each file - all in files named server.log, server2.log, etc. I'm parsing all of them to come up with the output I mentioned in my original post.

If actually counting the number of times a cron job shows up and outputting a total sum is too difficult, I could at least get the raw output from each file and do the addition myself to get the total amount a cron job shows up.

So, say I have 10 servers with:

/some/cron/here/

And 8 servers with:

/another/cron/here/

The final format I'm aiming for would be like so:

Cronjob | # of Servers | Every minute | Every hour | Every day | Every week | Every month
-----------------------------------------------------------------------------------------
CronHere| 10 | N | N | Y | Y | Y
CronHere| 8 | Y | N | N | Y | Y

The only dynamic variable here would be the number of servers that have each cron in their crontab. The other entries of N or Y should be static amongst each individual cron job as they are all setup the same way. The only thing that varies amongst the same cron job on each server is the time it executes, but since we're just adding a Y or N that's of no consequence.

Edit:

Here's the output of the latest version of the script with the missing bits added in to get it to display right:

$ ruby parse3.rb 
Minutes   Hours  DayOfMonth  Month DayOfWeek
min = Y, hour = N, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = N, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = N, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = N, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = N, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N
min = Y, hour = Y, day of month = N, month = N, day of week = N

And here's the code:

#!/usr/bin/ruby 

def doYorN(part)
  if part == "*"
     "N"
  else
     "Y"
   end
end
file = File.new("cn.log", "r")
puts "Minutes   Hours  DayOfMonth  Month DayOfWeek"
while (line = file.gets)
    parts = line.split(' ')
    puts "min = #{doYorN(parts[0])}, hour = #{doYorN(parts[1])}, day of month = #{doYorN(parts[2])}, month = #{doYorN(parts[3])}, day of week = #{doYorN(parts[4])}"
end
file.close

Last edited by Striketh (2011-11-08 23:42:30)