How to split a multivalue field into single values?

[alexandermunce]

I am working with a field < source_ip > containing three IP addresses and am wanting to split the values of that field into individual values.

The field data currently looks like this:

10.1.0.1 192.168.0.1, 192.168.2.1
10.1.0.1 192.168.3.1, 192.168.4.2

As you can see, the first and second IP addresses are separated by a space and the second and third is separated by , (a comma and a space).

I have tried using SPL commands to split this data, but I feel that a command which uses REGEX may be more suitable.

Is it possible to split these IP addresses into individual values in the same field, ie the < source_ip > field will then contain a list of single IP addresses (rather than splitting the three values into three separate fields).

[richgalloway · Accepted solution]

If the field always contains exactly three IP addresses then this rex command should do the job.

... | rex field=foo "(?<ip1>[^\s]+)\s(?<ip2>[^,]+),\s(?<ip3>.*)" | ...

[alexandermunce]

@richgalloway

One other question - I feel that it may likely be the case that only the 2nd or 3rd IP address may be relevant in the end - can I tweak your REGEX code so that it ignore the first and/or second IP and only extracts the third?

[richgalloway]

Extract just the third IP address with this regex

... | rex field=foo ", (?<ip>.*)" | ...

You also requested an explanation of my original regex.
(?<ip1>[^\s]+) takes everything up to the first white space and puts it into field 'ip1'
\s(?<ip2>[^,]+) skips a space then puts everything up to the next comma into field 'ip2'
,\s(?<ip3>.*) skips a comma and a space and puts the remaining characters into field 'ip3'.

[alexandermunce]

You are a gentleman and a scholar, thank you kindly!

Answer accepted and upvoted.

[alexandermunce]

@richgalloway

Thank you for your response - quick follow up question - can I extract all three of the values to the SINGLE new field - perhaps similar to the below;

... | rex field=foo "(?<ip_new>[^\s]+)\s(?<ip_new>[^,]+),\s(?<ip_new>.*)" | ...

Also - not sure if you have the time, but care to explain the logic behind your REGEX code?

[richgalloway]

Regular expressions don't allow the same group name to be used more than once so your rex command won't work.

To split the field into a new (multi-valued) field, use the split function.

... | eval bar=split(replace(foo, ",", "")," ") | ...

The replace function removes the comma. The result is a multi-valued field containing the three IP addresses. You can use mv commands to access them.