script to test a file.

[Rick Bragg]

Hi,

I want to write a script that will test the contents of a file.

The file being tested will pass only if it contains nothing more than an
ip address on one line. Does anyone have a sample of a simple regex to
accomplish this?

Thanks
Rick

[Andrew Gaffney]

Rick Bragg wrote:

> Hi,
>
> I want to write a script that will test the contents of a file.
>
> The file being tested will pass only if it contains nothing more than an
> ip address on one line. Does anyone have a sample of a simple regex to
> accomplish this?

/\d+\.\d+\.\d+\.\d+\n?/s

--
Andrew Gaffney

[Wiggins D Anconia]

> Rick Bragg wrote:

> > Hi,
> >
> > I want to write a script that will test the contents of a file.
> >
> > The file being tested will pass only if it contains nothing more

than an

> > ip address on one line. Does anyone have a sample of a simple regex to
> > accomplish this?

>
> /\d+\.\d+\.\d+\.\d+\n?/s
>

Beware of insufficient regexes in regex clothing. The above will
certainly find one or more digits followed by a dot, followed by one or
more digits followed by a dot, etc. But it does *NOT* match an IP
address...

/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/

Is at least closer, but it is still not sufficient, as IP addresses are
bounded, I believe, at 255 so 336.47.894.0, will match the above, but is
not a valid IP address.

How strict do you need to be, how sure are you about the data in the files?

[url]http://danconia.org[/url]

[Jerry Rocteur]

On Wednesday, Oct 29, 2003, at 19:43 Europe/Brussels, Wiggins d Anconia
wrote:

>
>

>> Rick Bragg wrote:

>>> Hi,
>>>
>>> I want to write a script that will test the contents of a file.
>>>
>>> The file being tested will pass only if it contains nothing more

> than an

>>> ip address on one line. Does anyone have a sample of a simple regex
>>> to
>>> accomplish this?

>>
>> /\d+\.\d+\.\d+\.\d+\n?/s
>>

>
> Beware of insufficient regexes in regex clothing. The above will
> certainly find one or more digits followed by a dot, followed by one or
> more digits followed by a dot, etc. But it does *NOT* match an IP
> address...
>
> /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/
>
> Is at least closer, but it is still not sufficient, as IP addresses are
> bounded, I believe, at 255 so 336.47.894.0, will match the above, but
> is
> not a valid IP address.
>
> How strict do you need to be, how sure are you about the data in the
> files?
>

Doing it with plain regexp won't work in one go, you could put the
above between (),(),() and check with $1,$2,$3 etc that you don't have
an 894..

However, you could also use Regexp::Common


Jerry

[Robert Citek]

At 11:43 AM 10/29/2003 -0600, Andrew Gaffney wrote:

>Rick Bragg wrote:

>>Hi,
>>I want to write a script that will test the contents of a file.
>>The file being tested will pass only if it contains nothing more than an
>>ip address on one line. Does anyone have a sample of a simple regex to
>>accomplish this?

>
>/\d+\.\d+\.\d+\.\d+\n?/s

Slightly more complex and slightly more robust:

cat <<EOF | perl -lne "print if /^(\d{1,3}\.){3}\d{1,3}$/"
hello
1.2.3.4.5
1.2.3
1.2.3.4
1.2.3.4 hello
hello 1.2.3.4
123.123.123.123
1234.123.123.123
EOF

Regards,
- Robert

[Brian Gerard]

And the clouds parted, and Wiggins d Anconia said...

>
>

> > Rick Bragg wrote:

> > > Hi,
> > >
> > > I want to write a script that will test the contents of a file.
> > >
> > > The file being tested will pass only if it contains nothing more

> than an

> > > ip address on one line. Does anyone have a sample of a simple regex to
> > > accomplish this?

> >
> > /\d+\.\d+\.\d+\.\d+\n?/s
> >

>
> Beware of insufficient regexes in regex clothing. The above will
> certainly find one or more digits followed by a dot, followed by one or
> more digits followed by a dot, etc. But it does *NOT* match an IP
> address...
>
> /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/
>
> Is at least closer, but it is still not sufficient, as IP addresses are
> bounded, I believe, at 255 so 336.47.894.0, will match the above, but is
> not a valid IP address.
>
> How strict do you need to be, how sure are you about the data in the files?
>

Good point.

At it's most basic, to match any valid IPv4 address alone on a line, I would
use
/\A((1?\d{1,2}|2([0-4]\d|5[0-5]))\.){3}(1?\d{1,2}|2([0-4]\d|5[0-5]))\z/

Which will match a string containing only a dotted quad from 0.0.0.0 to
255.255.255.255, inclusive. Note that I'm assuming the string in
question contains the _entire_ contents of the file.

A couple of things to note, though:
* A valid IP is actually any 32 bit integer from 0 to 4294967295 (try
putting 3639555427 in Mozilla (or supposedly any other well-behaved
browser... in other words, _not_ IE)... it will take you to Google
because that number is actually 216.239.53.99 - the address for
[url]www.google.com[/url] - in base-10).
* This pattern doesn't exclude RFC1918 reserved addresses (10/8,
172.16/12, and 192.168/16), or multicasts.
* It doesn't take netmasks into account. 1.2.3.255/16 is a valid
host address, while 1.2.3.255/24 is not (it's a broadcast).

Taking these sorts of things into account could make for a bit hairier
solution. ;) Caveat user.



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