TheLOGNAMEenvironment variable holds the user’s login name. Can we rely on its value being set properly? Can we rely on what the logname reports as the user’s login name?

What will be an ideal response?

Users can change their LOGNAME environment variables, so we can’t rely on its value being accurate. The logname command, on the other hand, tends to be morereliable. It usesgetlogin(3), which tries to correlate the caller’s controlling terminal with the entries in theutmp?le.