Permission Denied in bash script

I'm new to SW, trying to read a log file at /var/log in ubuntu 20.04.

i've add a bash monitor script to a template in SAM to get metrics from a MTA.

if the log file is in the home of the linux user declared in the User Name of credential its read perfect , but when i read from the place where must be (/var/log) it returns "permission denied".

so the question is , sorry for the obvious, What should i modify ?

Thank you very much in advance.