Splunk Dev

Doing my first scripted lookup, trying a basic hello world ... where do I start?

daniel333
Builder

All,

Trying to make a basic scripted python lookup. The examples and tutorials were just way over my head. So trying to do something simpler. I coped the example file and tried to simplify the problem a little. What I am aiming to do here is pass a field called 'mystring' and get back a field called 'myoutput'.

I am passing hello as the field value for mystring and expecting world as the value in the new field myoutput.

When I execute this I get the following

index=*
| head 1
| eval mystring = "hello"
| lookup mylookup mystring

I get" Script execution failed for external search command '/opt/splunk/etc/apps/TA-myapp/bin/mylookup.py'."

here is my python.

#!/usr/bin/env python

import csv
import sys


def main():

    if len(sys.argv) != 3:
        print("Usage: python mylookup.py [mystring] [myoutput]")
        sys.exit(1)

    # always passing hello as a eval mystring = "hello"
    mystring = sys.argv[1]
    myoutput = sys.argv[2]

    infile = sys.stdin
    outfile = sys.stdout

    r = csv.DictReader(infile)
    header = r.fieldnames

    w = csv.DictWriter(outfile, fieldnames=r.fieldnames)
    w.writeheader()

    for result in r:
            result[mystring] = "hello"
            result[myoutput] = "world"
            w.writerow(result)

main()
Labels (1)
0 Karma

harsmarvania57
Ultra Champion

Hi,

Have you configured transforms.conf for external lookup ?

Like

[mylookup]
external_cmd = mylookup.py mystring
fields_list = mystring,myoutput
0 Karma
Got questions? Get answers!

Join the Splunk Community Slack to learn, troubleshoot, and make connections with fellow Splunk practitioners in real time!

Meet up IRL or virtually!

Join Splunk User Groups to connect and learn in-person by region or remotely by topic or industry.

Get Updates on the Splunk Community!

At .conf26, Don’t Just See What’s Next. Help Shape It at Innovation Labs.

Long before a new capability reaches the keynote stage, it begins as an idea waiting to be tested. At ...

Forwarder Topology Guidance: Intermediate HF vs Intermediate UF

Why Universal Forwarders Should Not Be Used as Intermediate Forwarders A practical Splunk forwarding topology ...

Data Management Digest – August 2026

Data Management Digest   Welcome to the August 2026 edition of Data Management Digest! August was a big month ...