How to use Regex to trim the field?

[kiran331]

Hi, I have a field with DNS names, how to extract a host name from them?

for example,

abc123.ab.com
aca12.ba.xy.com

output i need

abc123
aca12

[DalJeanis · Accepted solution]

One way is

| rex field=mydnsfield "^(?<hostname>[^.]+)"

That will get everything that isn't a period, from the beginning, up to but not including the first period.

[adonio]

give this a try:
... | rex (?<field1>\w+)\.(?<field2>\w+)\.(?<field3>\w+)
https://regex101.com/r/uWt0Mf/1

hope it helps

[DalJeanis]

@adonio - (1) That's going to fail if any of the host names don't have three or more nodes. You should probably make the last one optional. (2) What's the purpose of the final .?

[adonio]

Thanks @DalJeanis!
wanted to demonstrate flexibility in case s/he needs more fields extracted
as always, great comments, appreciate it!
i guess the . implies i am writing more in my journal lately and i am trying to end a sentence with a .
edited the answer