program_invocation_name, program_invocation_short_name - obtain name used to invoke calling program

program_invocation_name  contains the name that was used to invoke the calling program.  This is the same
       as the value of argv[0] in main(), with the difference  that  the  scope  of  program_invocation_name  is
       global.

       program_invocation_short_name contains the basename component of name that was used to invoke the calling
       program.  That is, it is the same value as program_invocation_name, with all text up to and including the
       final slash (/), if any, removed.

       These variables are automatically initialized by the glibc run-time startup code.

       Standard C library (libc, -lc)

       program_invocation_name, program_invocation_short_name - obtain name used to invoke calling program

proc(5)

Linux man-pages 6.9.1                              2024-05-02                         program_invocation_name(3)

       GNU.

#define_GNU_SOURCE         /* See feature_test_macros(7) */
       #include<errno.h>externchar*program_invocation_name;externchar*program_invocation_short_name;

       The Linux-specific /proc/pid/cmdline file provides access to similar information.