String processing

Ruby
1

Hi
i am trying to automate cacti graph

after i add the device, its give me a result like bellow

Success - new device-id: (18)

problem is : how will i just get number 18 ??

thanks for help

2

On 8/15/2012 9:43 PM, Fosiul A. wrote:

thanks for help

a regular expression match of a number can match like that
/((\d))/

Regards,
Eliezer

3

hi
I am very new to ruby
what would be the syntax ??

i get output like this

uk-xxxxxxx-Z15A14
Adding uk-xxxxx-Z15A14 (uk-xxxx-Z15A14) as “Generic SNMP-enabled Host”
using SNMP v1 with community “public”
Success - new device-id: (26)

i will be able to parse the line by

cmd each

cmd.each do |item|
if ( item =~ /((\d))/ )
getnumber = item
end
end

will it work ??

4

sorry the code i wrote that does not do anything

syntax help would be really appreciate

5

You need to also make sure that you get the right line, not just pick
out the any digits

DATA.each do |line|
if line =~ /^Success - new device-id: ((\d+))/
puts $1
end
end

END
uk-xxxxxxx-Z15A14
Adding uk-xxxxx-Z15A14 (uk-xxxx-Z15A14) as “Generic SNMP-enabled Host”
using SNMP v1 with community “public”
Success - new device-id: (26)

The $1 is the captured value, the (\d+) part.

6

On 8/15/2012 10:00 PM, Fosiul A. wrote:

will it work ??

this output should be a string and is not enumerable so you can use each
but you can use “each_line” to inspect each line but “getnumber = item”
will not extract the number.
and instead of iterating over each line you can use one regex on the
whole string like:
cmd =~ /((\d+))/

you must use “\d+” to match one or more numbers
the =~ will give bad results on a whole string and you better use the
scan method.
cmd.scan /((\d+))/
this will return array of strings array
so this:
(cmd.scan /((\d+))/)[0][0]
will give you the result with a one liner.
and i just seen that Robert gave you a nice solution.

Regards,
Eliezer

7

On Wed, Aug 15, 2012 at 9:30 PM, Peter H.
[email protected] wrote:

You need to also make sure that you get the right line, not just pick
out the any digits

DATA.each do |line|
if line =~ /^Success - new device-id: ((\d+))/
puts $1
end

Alternatively

num = line[/^Success - new device-id: ((\d+))/, 1] and puts num

I find the solution with String#[] very elegant. :slight_smile:

Btw, if there is always just one number this shorter solution will
work as well - but is not so robust against other inputs:

num = line[/\d+/]

Kind regards

robert

8

Peter H. wrote in post #1072475:

You need to also make sure that you get the right line, not just pick
out the any digits

DATA.each do |line|
if line =~ /^Success - new device-id: ((\d+))/
puts $1
end
end

END
uk-xxxxxxx-Z15A14
Adding uk-xxxxx-Z15A14 (uk-xxxx-Z15A14) as “Generic SNMP-enabled Host”
using SNMP v1 with community “public”
Success - new device-id: (26)

The $1 is the captured value, the (\d+) part.

Hi thanks

but there is a problem , I have modified this as bellow

DATA.each do |line|
if line =~ /^Success - new device-id: ((\d+))/
device_id = $1
end
end

puts #{device_id}

and this does not return anything …

how can i use the value outside of the loop ??

i will try rest of the solution as well.

thanks you guys …

9

#!/usr/bin/ruby

host=ARGV[0]
puts host

cmd=php -q /var/lib/cacti/cli/add_device.php --description="#{host}" --ip="#{host}" --template=1 --community="public"

cmd.each do |line|
if line =~ /^Success - new device-id: ((\d+))/
device_id=$i
end
end

puts device_id ======== this does not give anything …

So now i will have to use hte device_id valu to execute another

commands.

10

Fosiul A. wrote in post #1072480:

but there is a problem , I have modified this as bellow

DATA.each do |line|
if line =~ /^Success - new device-id: ((\d+))/
device_id = $1
end
end

puts #{device_id}

and this does not return anything …

how can i use the value outside of the loop ??

put:

device_id = nil

before the loop. It’s one of the ruby scoping rules that if you first
assign to a variable inside a block, it disappears at the end of that
block.

11

Eliezer C. wrote in post #1072477:

On 8/15/2012 10:00 PM, Fosiul A. wrote:

will it work ??

this output should be a string and is not enumerable so you can use each
but you can use “each_line” to inspect each line but “getnumber = item”
will not extract the number.
and instead of iterating over each line you can use one regex on the
whole string like:
cmd =~ /((\d+))/

you must use “\d+” to match one or more numbers
the =~ will give bad results on a whole string and you better use the
scan method.
cmd.scan /((\d+))/
this will return array of strings array
so this:
(cmd.scan /((\d+))/)[0][0]
will give you the result with a one liner.
and i just seen that Robert gave you a nice solution.

Regards,
Eliezer

Hi thanks

this works perfec
host=ARGV[0]
puts host

cmd=php -q /var/lib/cacti/cli/add_device.php --description="#{host}" --ip="#{host}" --template=1 --community="public"

device_id = (cmd.scan /((\d+))/)[0][0]
puts device_id