How To "Gaslight" A Binary

Here is a very simple C code: int main () { uid_t uid = getuid (); struct passwd * pw = getpwuid ( uid ); printf ( "uid: %d, user: %s \n " , uid , pw -> pw_name ); return 0 ; } It simply prints your identity in the current session. Let's run it: [ local @DouLen] ~ › ./whoami uid: 0, user: root The program says I'm root, but look at the prompt: I'm logged in as local . There isn't any privilege escalation in the code, and the program isn't run with sudo or similar. But if so, why is the program t