RE: problems parsing a DHCP.leases file.
Hans,
This script works really well but, I am a bit confused on what you are doing
with this: local $/=}\n; I have not seen local used much as I thought it
was replaced by my. It almost looks like you are defining the end of each
lease entry with a closing curly brace and a new line. Does the dollar sign
indicate that is the end of the input?
As for the regex matches the first two make sense to me but I am a bit
confused on the third one
my ($client_hostname)=$record=~/^\s+client-hostname\s+([\w.-_]+)/m
I can see that we are creating a variable called $client_hostname which is
defined by a match to $record which is feed in by the filehandle. I see
that we are searching for a line starting with one or more spaces followed
by client-hostname then one or more spaces followed by one word character
and anything else but what does the -_ do? And what does the m on the
outside do?
Thanks again for the example it is really interesting and has helped me.
-angus
-Original Message-
From: Hans Meier (John Doe) [mailto:[EMAIL PROTECTED]
Sent: Monday, February 27, 2006 12:53 AM
To: beginners@perl.org
Subject: Re: problems parsing a DHCP.leases file.
Angus am Montag, 27. Februar 2006 08.25:
Hi all,
I am having some problems filling a variable based on the contents of a
dhcpd.leases file. All I want at this time is the hostname and ip
address.
My eventual goal is to create hash of hashes with this information but for
now I just want to read in the file and see that I have defined my
variables correctly. I am able to get the IP address but the $hostname
variable is always undefined. The syntax for any given host in a leases
file looks like this:
lease 10.10.97.207 {
starts 2 2005/12/20 16:10:51;
ends 2 2005/12/20 20:10:51;
tstp 2 2005/12/20 20:10:51;
binding state free;
hardware ethernet 00:0b:97:2b:ea:fe;
uid \001\000\013\227+\352\376;
client-hostname HOST1;
}
Here is what I have so far.
#!/usr/bin/perl
#
use strict;
use warnings;
my $dhcp_data = dhcpd.leases;
my %dhcpd;
my $ip;
my $hostname;
{
open (DHCPD, $dhcp_data) || die Can't open $dhcp_data $!\n;
while (my $line = DHCPD) {
next if ($line =~ /^\s*$/ or # blank line
$line =~ /^\s*#/ );
if ($line =~ /^lease (\d+\.\d+\.\d+\.\d+)/) {
$ip = $1; }
elsif ($line =~ /^client-hostname/) {
$hostname = $1; }
else {next;};
print I found IP:$ip\n;
print I found Hostname: $hostname\n;
}
}
Here is a way to process one lease { }
after another, with the possibility to extract every field you want.
I think it is easy to read, understand, and alter.
=
#!/usr/bin/perl
use strict;
use warnings;
local $/=}\n; # look here!
while (my $record=DATA) {
#print *** $record ***; # for debugging record extracting
my ($lease)=$record=~/lease\s+(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/;
my ($binding_state)=$record=~/^\s+binding\s+state\s+(\w+)/m;
my ($client_hostname)=$record=~/^\s+client-hostname\s+([\w.-_]+)/m;
print lease '$lease' (host '$client_hostname') has .
binding state '$binding_state'\n;
}
__DATA__
lease 10.10.97.207 {
starts 2 2005/12/20 16:10:51;
ends 2 2005/12/20 20:10:51;
tstp 2 2005/12/20 20:10:51;
binding state free;
hardware ethernet 00:0b:97:2b:ea:fe;
uid \001\000\013\227+\352\376;
client-hostname HOST1;
}
lease 10.10.97.208 {
starts 2 2005/12/20 16:10:51;
ends 2 2005/12/20 20:10:51;
tstp 2 2005/12/20 20:10:51;
binding state free;
hardware ethernet 00:0b:97:2b:ea:fe;
uid \001\000\013\227+\352\376;
client-hostname HOST2;
}
=
This prints out:
lease '10.10.97.207' (host 'HOST1') has binding state 'free'
lease '10.10.97.208' (host 'HOST2') has binding state 'free'
hth,
Hans
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Re: problems parsing a DHCP.leases file.
[ Please do not top-post. Please remove any quoted text that is not relevant
to your post. ]
Angus wrote:
From: Hans Meier (John Doe)
Here is a way to process one lease { }
after another, with the possibility to extract every field you want.
I think it is easy to read, understand, and alter.
=
#!/usr/bin/perl
use strict;
use warnings;
local $/=}\n; # look here!
while (my $record=DATA) {
#print *** $record ***; # for debugging record extracting
my ($lease)=$record=~/lease\s+(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/;
my ($binding_state)=$record=~/^\s+binding\s+state\s+(\w+)/m;
my ($client_hostname)=$record=~/^\s+client-hostname\s+([\w.-_]+)/m;
print lease '$lease' (host '$client_hostname') has .
binding state '$binding_state'\n;
}
This script works really well but, I am a bit confused on what you are doing
with this: local $/=}\n;
$/ is the Input Record Separator variable.
perldoc perlvar
I have not seen local used much as I thought it
was replaced by my.
It has been for user defined variables however you still have to use local for
Perl's special variables like $/.
It almost looks like you are defining the end of each
lease entry with a closing curly brace and a new line. Does the dollar sign
indicate that is the end of the input?
No, the dollar sign indicates that / is the name of a scalar variable.
As for the regex matches the first two make sense to me but I am a bit
confused on the third one
my ($client_hostname)=$record=~/^\s+client-hostname\s+([\w.-_]+)/m
I can see that we are creating a variable called $client_hostname which is
defined by a match to $record which is feed in by the filehandle. I see
that we are searching for a line starting with one or more spaces followed
by client-hostname then one or more spaces followed by one word character
and anything else but what does the -_ do?
The hythen (-) in a character class defines a range of characters unless it is
at the beginning or end of the character class so '.-_' is the range of
characters starting at '.' and ending at '_'. That is probably a mistake but
I would have to check the RFCs to confirm that. Hans probably meant '[\w._-]'
instead?
And what does the m on the
outside do?
The /m option means that ^ will match at the beginning of a line inside the
string in $record instead of at the beginning of $record.
John
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program
fulfillment
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Re: problems parsing a DHCP.leases file.
Hi,
here is wrong:
elsif ($line =~ /^client-hostname/) {
$hostname = $1; }
for the line like that:
client-hostname HOST1;
I think maybe you should do:
elsif ($line =~ /^\s*client-hostname\s+\(.*?)\){
$hostname = $1;}
HTH.
--
Jeff Pang
NetEase AntiSpam Team
http://corp.netease.com
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Re: problems parsing a DHCP.leases file.
you need to match something.
You probably meant:
elsif ($line =~ /^client-hostname\s+([a-z0-9\-\.]+)/i) {
On the other hand, there is probably a module that already deals with
this and would save you even more coding time.
Ryan
On Feb 27, 2006, at 1:25 AM, Angus wrote:
elsif ($line =~ /^client-hostname/) {
$hostname = $1; }
RE: problems parsing a DHCP.leases file.
Ryan,
Thanks for the tip however, in this case what I am trying to do (I think) is
find a line that starts with client-hostname then match my variable
$hostname to the second thing that the regex matches in that line $1. It
works for the ip address but fails for the hostname. I did try to regex
match but it still returns an undef variable...
-angus
-Original Message-
From: The Ghost [mailto:[EMAIL PROTECTED]
Sent: Monday, February 27, 2006 12:13 AM
To: Angus
Cc: beginners@perl.org
Subject: Re: problems parsing a DHCP.leases file.
you need to match something.
You probably meant:
elsif ($line =~ /^client-hostname\s+([a-z0-9\-\.]+)/i) {
On the other hand, there is probably a module that already deals with
this and would save you even more coding time.
Ryan
On Feb 27, 2006, at 1:25 AM, Angus wrote:
elsif ($line =~ /^client-hostname/) {
$hostname = $1; }
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Re: problems parsing a DHCP.leases file.
When I change to :
...
elsif ($line =~ /^\s+?client-hostname\s+([a-z0-9\-\.]+)/i) {
...
I found IP:10.10.97.207
I found Hostname:
I found IP:10.10.97.207
I found Hostname: HOST1
Seems you have some space there. Also, you probably want to move
your my $hostname and my $ip statements. If a hostname line wasn't
found, it would show up as the previously defined hostname (same with
IP)!
Anyway, that should help, it DOES find it - this should help you
solve the problem.
Ryan
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Re: problems parsing a DHCP.leases file.
Angus am Montag, 27. Februar 2006 08.25:
Hi all,
I am having some problems filling a variable based on the contents of a
dhcpd.leases file. All I want at this time is the hostname and ip address.
My eventual goal is to create hash of hashes with this information but for
now I just want to read in the file and see that I have defined my
variables correctly. I am able to get the IP address but the $hostname
variable is always undefined. The syntax for any given host in a leases
file looks like this:
lease 10.10.97.207 {
starts 2 2005/12/20 16:10:51;
ends 2 2005/12/20 20:10:51;
tstp 2 2005/12/20 20:10:51;
binding state free;
hardware ethernet 00:0b:97:2b:ea:fe;
uid \001\000\013\227+\352\376;
client-hostname HOST1;
}
Here is what I have so far.
#!/usr/bin/perl
#
use strict;
use warnings;
my $dhcp_data = dhcpd.leases;
my %dhcpd;
my $ip;
my $hostname;
{
open (DHCPD, $dhcp_data) || die Can't open $dhcp_data $!\n;
while (my $line = DHCPD) {
next if ($line =~ /^\s*$/ or # blank line
$line =~ /^\s*#/ );
if ($line =~ /^lease (\d+\.\d+\.\d+\.\d+)/) {
$ip = $1; }
elsif ($line =~ /^client-hostname/) {
$hostname = $1; }
else {next;};
print I found IP:$ip\n;
print I found Hostname: $hostname\n;
}
}
Here is a way to process one lease { }
after another, with the possibility to extract every field you want.
I think it is easy to read, understand, and alter.
=
#!/usr/bin/perl
use strict;
use warnings;
local $/=}\n; # look here!
while (my $record=DATA) {
#print *** $record ***; # for debugging record extracting
my ($lease)=$record=~/lease\s+(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/;
my ($binding_state)=$record=~/^\s+binding\s+state\s+(\w+)/m;
my ($client_hostname)=$record=~/^\s+client-hostname\s+([\w.-_]+)/m;
print lease '$lease' (host '$client_hostname') has .
binding state '$binding_state'\n;
}
__DATA__
lease 10.10.97.207 {
starts 2 2005/12/20 16:10:51;
ends 2 2005/12/20 20:10:51;
tstp 2 2005/12/20 20:10:51;
binding state free;
hardware ethernet 00:0b:97:2b:ea:fe;
uid \001\000\013\227+\352\376;
client-hostname HOST1;
}
lease 10.10.97.208 {
starts 2 2005/12/20 16:10:51;
ends 2 2005/12/20 20:10:51;
tstp 2 2005/12/20 20:10:51;
binding state free;
hardware ethernet 00:0b:97:2b:ea:fe;
uid \001\000\013\227+\352\376;
client-hostname HOST2;
}
=
This prints out:
lease '10.10.97.207' (host 'HOST1') has binding state 'free'
lease '10.10.97.208' (host 'HOST2') has binding state 'free'
hth,
Hans
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