Sandcat fails to start when whoami is not found

[alexanderkent]

Describe the bug Sandcat agent fails on startup when whoami command is not found on the platform. https://github.com/mitre/sandcat/blob/e903198c4e0a197e8df1e04bbf8c3324107afe6f/gocat/agent/agent_util.go#L15

To Reproduce Steps to reproduce the behavior:

1. Temp remove whoami e.g. rename, alter path etc
2. Launch sandcat agent -v

./sandcat-arm64 -v
Starting sandcat in verbose mode.
[-] Error when initializing agent: exec: "whoami": executable file not found in $PATH
[-] Exiting.

Expected behavior Not all platforms have whoami -- soft-fail instead of a terminal error?

Desktop (please complete the following information):

• arm64 / IoT / debian