$0
The name the script was called by — itself, on the label.
Inside a script, $0 is the path used to invoke it — raw material for usage messages: usage: $0 file…. In an interactive shell, it is the shell's own name.
It stays out of the positional dance: shift moves $1, $2 and onward, but $0 does not budge.
$ cat identifica.sh
#!/bin/bash
echo "eu sou $0"
$ ./identifica.sh
eu sou ./identifica.sh