man argv0 (1): run a program with a specified 0th argument

SYNOPSIS

argv0 realname zero [ arg ... ]

argv0 runs the program stored as realname on disk, with the given arguments. It sets the 0th argument of the program to zero.

For example,

argv0 /bin/csh -bin/csh

runs /bin/csh with a 0th argument of -bin/csh. csh will think it is a login shell and behave accordingly.

argv0 can be used to run some inetd wrappers under tcpserver.