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Full Discussion: Ruby: "Can't convert nil into String" error
Top Forums Programming Ruby: "Can't convert nil into String" error Post 302767857 by Elvirnith on Thursday 7th of February 2013 03:20:10 PM
Old 02-07-2013
Ruby: "Can't convert nil into String" error
Hi there,

I'm relatively new to ruby and I'm trying to put together this script to process cron jobs on a server. It's almost working, except I can't figure out what exactly is wrong and how to fix it. Can anyone point me in the right direction?

Here's what I have so far:

Code:
require 'rubygems'
require 'crontab-parser'

start_time = Time.parse(ARGV[0])
end_time = Time.parse(ARGV[1])

File.open('/root/flagged_cron_jobs.log', 'w+') do |f2|

crontab_data = File.readlines(ARGV[2]).select {|line| line =~ /^[0-9*]/}
cron  = CrontabParser.new(crontab_data.join("\n"))
(start_time..end_time).each do |timestamp|
  next unless timestamp.sec.to_i == 0
  cron.each do |cron_entry|
Dir["/var/spool/cron/*"].each do |file|
  username = file.split("/").last
  crontab = CrontabParser.new(File.read(file))
  puts "User: #{username}"
    if cron_entry.should_run?(timestamp)
      f2.puts "#{timestamp}\t#{cron_entry.cmd}"

        end
      end
    end
  end
end

Here's the error:

Code:
cron_parse.rb:9:in `readlines': can't convert nil into String (TypeError)
	from cron_parse.rb:9
	from cron_parse.rb:7:in `open'
	from cron_parse.rb:7

Command being executed is like so:

Code:
ruby cron_parse.rb "Thurs Feb 7 01:00 UTC 2013" "Thurs Feb 7 01:14 UTC 2013"

I suspect it's because of the addition of
Code:
 crontab = CrontabParser.new(File.read(file))

in relation to
Code:
cron  = CrontabParser.new(crontab_data.join("\n"))

but I'm not really sure of how to deal with this.
Last edited by jim mcnamara; 02-07-2013 at 04:53 PM..
 

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LEARN ABOUT DEBIAN

racc

racc(1) 						      General Commands Manual							   racc(1)

NAME

       racc - Ruby LALR parser generator

SYNOPSIS

       racc [options] file

DESCRIPTION

       Racc is a LALR(1) parser generator.  It is written in Ruby itself, and generates Ruby program.

OPTIONS

       -g, --debug
	      output parser for user level debugging.

       -o, --output-file <outfile>
	      file name of output.  [<fname>.tab.rb]

       -e, --executable <rubypath>
		  insert #! line in output.  ('ruby' to default)

       -E, --embedded
	      output file which don't need runtime.

       -l, --no-line-convert
	      never convert line numbers.  (for ruby<=1.4.3)

       -c, --line-convert-all
	      convert line numbers also header and footer.

       -a, --no-omit-actions
	      never omit actions.

       -v, --verbose
	      create <filename>.output file.

       -O, --log-file <fname>
	      file name of verbose output.  [<fname>.output]

       -C, --check-only
	      syntax check only.

       -S, --output-status
	      output status time to time.

       --no-extentions
	      run without any ruby extentions.

       -h, --help
	      print this message and quit.

       --version
	      print version and quit.

       --runtime-version
	      print runtime version and quit.

       --copyright
	      print copyright and quit.

SEE ALSO

       /usr/share/doc/racc/html.en/index.html (English) or /usr/share/doc/racc/html.ja/index.html (Japanese).

								    April 2005								   racc(1)
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