The line of code in red is what I am asking about. Could you tell me what output from the line of code in red would yield on the three examples given. I think I understand that the $zone will be the first field and $ip will be the second. I am sure you could do some sort of print statement to get that info but I just don't know how.
The issue is it appears that the script is ignoring the line in the config with a "-" dash in it.
If I way off base on this I will not be surprised.
The line of code in red is what I am asking about. Could you tell me what output from the line of code in red would yield on the three examples given.
...
The regular expression in red will *NOT* match any of the 3 lines, as the following adaptation of your script into a Perl one-liner shows:
Code:
$
$ # display the content of the config file
$ cat config.txt
3.crakatxr.com 12.245.255.67
01o02n8cf01.com 12.254.235.231
543-lwp-277.mxtosehp.com 12.222.246.212
$
$
$ # run a Perl one-liner that has the relevant regex, on the config file
$
$ perl -lne 'if (m/^\s*([a-zA-Z][a-zA-Z0-9.]+)\s+(\d+\.\d+\.\d+\.\d+)/){print "Matched: zone = $1, ip = $2"} else {print "No match"}' config.txt
No match
No match
No match
$
$
As to why it does not match - you'd see it quickly if you break down the regex:
Code:
/^\s*([a-zA-Z][a-zA-Z0-9.]+)\s+(\d+\.\d+\.\d+\.\d+)/ => Match a line in the input stream if:
(1) ^ = At the beginning of the line, (there exist)
(2) \s* = Zero or more occurrences of whitespace i.e. blanks or tabs
(3) [a-zA-Z] = followed by a single upper or lower case letter of the English alphabet
(4) [a-zA-Z0-9.]+ = followed by one or more occurrences of any combination of uppercase letters, lowercase letters, digits from 0 to 9, the period (.) character
[
Remember the matched result of (3) appended by (4) above and assign it to a "special" variable called "$1"
]
(5) \s+ = followed by one or more occurrences of whitespace i.e. blanks or tabs
(6) \d+\.\d+\.\d+\.\d+ =
one or more occurrences of digits (0-9) followed by the period (.) character,
followed by
one or more occurrences of digits (0-9) followed by the period (.) character,
followed by
one or more occurrences of digits (0-9) followed by the period (.) character,
followed by
one or more occurrences of digits (0-9)
[
Remember the matched result of (6) above and assign it to the next "special" variable called "$2"
]
If a match does happen, then assign the value of "$1" to $zone, and "$2" to $ip.
Now, as you can see, token no. (3) above would fail because none of the 3 lines in your config file have a upper or lower case English letter at the beginning. (All the 3 lines have digits at the beginning.)
Quote:
...
The issue is it appears that the script is ignoring the line in the config with a "-" dash in it.
...
As to how this can be fixed. You may want to be explicit and specify all the characters that you could encounter in the "zone" value, in your regex.
Here's one way to do it:
Code:
$
$ # display the content of the config file
$ cat config.txt
3.crakatxr.com 12.245.255.67
01o02n8cf01.com 12.254.235.231
543-lwp-277.mxtosehp.com 12.222.246.212
$
$
$ # run a Perl one-liner that has the relevant regex, on the config file
$ perl -lne 'if (/^\s*([a-zA-Z0-9.-]+)\s+(\d+\.\d+\.\d+\.\d+)/){print "Matched: zone = $1, ip = $2"} else {print "No match"}' config.txt
Matched: zone = 3.crakatxr.com, ip = 12.245.255.67
Matched: zone = 01o02n8cf01.com, ip = 12.254.235.231
Matched: zone = 543-lwp-277.mxtosehp.com, ip = 12.222.246.212
$
$
I've specified all the different characters that I expect in "zone", in the first token of the regex which is within parenthesis. That gets stored in special variable "$1". The remaining part of the regex is identical to yours.
Of course, there are other ways of writing the regex as well, depending on how strict you want your matching pattern to be. You could even use the split function and thereby avoid the regex. As it usually happens with Perl, there's more than one way to do it.
tyler_durden
This User Gave Thanks to durden_tyler For This Post:
Thank you very much for the your time spent explaining this to me is the detail that you did. I don't understand it all yet but will review to see if I can make this work. I want to understand it and not just plug the code in. I do appreciate it.
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