What is the difference between --init-file and --rcfile?

Solution 1:

They are synonymous.

From the shell.c file of bash-4.3 source:

long_args[] = {
....
  { "init-file", Charp, (int *)0x0, &bashrc_file },
....
  { "rcfile", Charp, (int *)0x0, &bashrc_file },
....
};

As you can see they are defined the same way and also works the same way.

The parameter bashrc_file stores the filename.

For further assurance, the CHANGES file in the source contains:

Added a new '--init-file' invocation argument as a synonym for '--rcfile', per the new GNU coding standards.