Re: Reading a value from a hash using a variable for the key
If so, how print TTL = $line\n does give me the right value ! (I
get TTL = 125 if ping to Windows machine.
Thanks, for your answers.
On Jan 21, 4:30 pm, rob.di...@gmx.com (Rob Dixon) wrote:
On 21/01/2011 05:50, Erez Schatz wrote:
On 20 January 2011 15:38, Eyal B.ewinst...@gmail.com wrote:
I'm getting an error on the line where I should use the TTL variable -
and take the right value from the hash (%list) :Use of uninitialized
value in print at D:\system\perl\os-rec\os-rec5_.pl line 24
,HANDLE line 3.
Any idea ?
if($line =~ TTL=)
{
$line =~ s/.*TTL=//;
print TTL = $line\n;
print $list{$line} ;
# print Machine $machine_IP is
$list{$line} ;
last; }
Assuming a specific line is made of nothing but TTL=, then $line =~
s/.*TTL=//; will erase the line, leaving you with an empty
(uninitialized) $line variable.
No it won't, it will leave $line containing a null (zero-length) string.
There is no way to change a string value to uninitialized (undef) by
deleting characters from it.
- Rob
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Re: Reading a value from a hash using a variable for the key
On Jan 21, 11:42 pm, ewinst...@gmail.com (Eyal B.) wrote:
On Jan 21, 4:30 pm, rob.di...@gmx.com (Rob Dixon) wrote:
On 21/01/2011 05:50, Erez Schatz wrote:
On 20 January 2011 15:38, Eyal B.ewinst...@gmail.com wrote:
I'm getting an error on the line where I should use the TTL variable -
and take the right value from the hash (%list) :Use of uninitialized
value in print at D:\system\perl\os-rec\os-rec5_.pl line 24
,HANDLE line 3.
Any idea ?
if($line =~ TTL=)
{
$line =~ s/.*TTL=//;
print TTL = $line\n;
print $list{$line} ;
# print Machine $machine_IP is
$list{$line} ;
last; }
I found the issue, and resolve it
This regex clean unnecessary, extra digits: $line =~/.*TTL=\s*(\S+)\s*$/;
Assuming a specific line is made of nothing but TTL=, then $line =~
s/.*TTL=//; will erase the line, leaving you with an empty
(uninitialized) $line variable.
No it won't, it will leave $line containing a null (zero-length) string.
There is no way to change a string value to uninitialized (undef) by
deleting characters from it.
- Rob
ok. So why on print TTL = $line\n; I do get TTL = 125, if it's
undefined ?
Thanks, Rob, for your answer.
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Re: Reading a value from a hash using a variable for the key
On Jan 21, 4:30 pm, rob.di...@gmx.com (Rob Dixon) wrote:
On 21/01/2011 05:50, Erez Schatz wrote:
On 20 January 2011 15:38, Eyal B.ewinst...@gmail.com wrote:
I'm getting an error on the line where I should use the TTL variable -
and take the right value from the hash (%list) :Use of uninitialized
value in print at D:\system\perl\os-rec\os-rec5_.pl line 24
,HANDLE line 3.
Any idea ?
if($line =~ TTL=)
{
$line =~ s/.*TTL=//;
print TTL = $line\n;
print $list{$line} ;
# print Machine $machine_IP is
$list{$line} ;
last; }
Assuming a specific line is made of nothing but TTL=, then $line =~
s/.*TTL=//; will erase the line, leaving you with an empty
(uninitialized) $line variable.
No it won't, it will leave $line containing a null (zero-length) string.
There is no way to change a string value to uninitialized (undef) by
deleting characters from it.
- Rob
ok. So why on print TTL = $line\n; I do get TTL = 125, if it's
undefined ?
Thanks, Rob, for your answer.
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Re: Reading a value from a hash using a variable for the key
Tried to implement your recommendations step by step .
#! C:\Perl\bin\perl
use strict;
use warnings;
my %list = (60=linux,61=linux,62=linux,63=linux,
64=linux,65=linux,125=Windows,126=Windows,127=Windows,
128=Windows,250=Unix,251=Unix,252=Unix,253=Unix,
254=Unix,255=Unix, 256=Unix,257=Unix,258=Unix,
259=Unix,260=Unix);
my $path = hosts.txt ;
# open (MACHINES,$path) or die Couldn't open file for writing;
open my $input_fh, , $path
or die Could not open '$path' - $!;
# Shlomi, you wrote : Use three args open and don't use bareword file
handles...
# I'm asking : Trying to implement that (Though, didn't understand
what is bareword)where do I indicate the MACHINES handle ?
my $machine_IP ;
while ($machine_IP = MACHINES)
{
chomp($machine_IP) ;
my $line ;
my $cmd ;
$cmd = ping $machine_IP;
open(HANDLE,$cmd|);
# Shlomi, you wrote : You should use three-args open, lexical
filehandles and or die.
# I'm asking : Can you pls show me how should I write that ?
# Furthermore, use $cmd is not needed here as you can interpolate
directly from $cmd.
# I didn't understand what that means.
while ($line = HANDLE)
{
if($line =~ TTL=)
# No need for wrapping $line in double quotes here as $line is a
string.
# as mentioned above
{
$line =~ s/.*TTL=//;
print TTL = $line\n;
print $list{$line} ;
last;
}
# You can do all that in one regex match.
# I didn't reach so far ... Is that
# if (my ($ttl) = $line =~ m{TTL=(\d+)})
# print Machine $machine_IP is
$list{$line} ;
}
}
close HANDLE;
close MACHINES;
# Without make the changes about the File Handle -
I still got the error : Use of uninitialized value within %list in
print at C:\system\Perl\OS-recognize\os-rec5.1_.pl line 35, HANDLE
line 4.
Thanks, Shlomi,
Eyal.
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Re: Reading a value from a hash using a variable for the key
On Jan 21, 7:50 am, moonb...@gmail.com (Erez Schatz) wrote:
On 20 January 2011 15:38, Eyal B. ewinst...@gmail.com wrote:
I'm writing a scripts that check the TTL of the ping and found the OS.
According the TTL - the script should let me know which OS it is :
Linux/ Windows or Unix (Hash table)
I'm getting an error on the line where I should use the TTL variable -
and take the right value from the hash (%list) :Use of uninitialized
value in print at D:\system\perl\os-rec\os-rec5_.pl line 24
, HANDLE line 3.
Any idea ?
if($line =~ TTL=)
{
$line =~ s/.*TTL=//;
print TTL = $line\n;
print $list{$line} ;
# print Machine $machine_IP is
$list{$line} ;
last; }
Assuming a specific line is made of nothing but TTL=, then $line =~
s/.*TTL=//; will erase the line, leaving you with an empty
(uninitialized) $line variable.
A way to debug this will be to include a print $line just before the
substitution, so you could find what is happening in each stage of the
iteration.
--
Erez
La perfection soit atteinte non quand il n'ya plus rien à ajouter,
mais quand il n'ya plus rien à retrancher.
Hi Erez
print TTL = $line\n; Does give me the right value ! (I.e TTL = 125)
Also print $list{125} ; return the right value
But this is not working : print $list{$line} ;
What can happen for the variable ?
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Reading a value from a hash using a variable for the key
I'm writing a scripts that check the TTL of the ping and found the OS.
According the TTL - the script should let me know which OS it is :
Linux/ Windows or Unix (Hash table)
I'm getting an error on the line where I should use the TTL variable -
and take the right value from the hash (%list) :Use of uninitialized
value in print at D:\system\perl\os-rec\os-rec5_.pl line 24
, HANDLE line 3.
Any idea ?
#! C:\Perl\bin\perl -w
use strict;
use warnings;
my %list = (60,linux,61,linux,62,linux,63,linux,64,linux,
65,linux,125,Windows,126,Windows,127,Windows,128,Windows,
250,Unix,251,Unix,252,Unix,253,Unix,254,Unix,255,Unix,
256,Unix,257,Unix,258,Unix,259,Unix,260,Unix);
my $path = hosts.txt ;
my $machine_IP ;
my $cmd ;
# read machines hosts names List from the txt file c:1.txt and take
the TTL data to th e variable: $line
open (MACHINES,$path) or die Couldn't open file for writing;
while ($machine_IP = MACHINES)
{
chomp($machine_IP) ;
my $line ;
$cmd = ping $machine_IP;
open(HANDLE,$cmd|);
while ($line = HANDLE)
{
if($line =~ TTL=)
{
$line =~ s/.*TTL=//;
print TTL = $line\n;
print $list{$line} ;
# print Machine $machine_IP is $list{$line} ;
last; }
}
}
close HANDLE;
close MACHINES;
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