When using a shell script on my splunk server I am able to access variables with no problem ie
java -jar custom.jar -val $(date +%Y%m%d_%H%M)
However, when using the same script with the Universal Forwarder as a .path file the it does not execute.
Any suggestions on how to achieve this as a scripted input with the UF?
Is it possible you need to use absolute paths to the java and date commands? I'd suspect that the PATH in use by Splunk might not include the location of java (date should work as such).
Alternatively perhaps try set -x in the script and watch to output to see what is happening?
Finally, I'm assuming you have execute permissions on the script...