LOGNAME(1) General Commands Manual LOGNAME(1)
logname – display user's login name
The logname utility writes the user's login name to standard output
followed by a newline.
The logname utility explicitly ignores the LOGNAME and USER environment
variables because the environment cannot be trusted.
The logname utility exits 0 on success, and >0 if an error occurs.
who(1), whoami(1), getlogin(2)
The logname utility conforms to IEEE Std 1003.2-1992 (“POSIX.2”).
The logname command appeared in 4.4BSD.
BSD 4.4 June 9, 1993 BSD 4.4