$0 can accept piped data, STDIN redirection [<filename.txt], text strings following the command as arguments, or filenames as arguments. Only one of these methods can be used at a time, so please see the note on precedence. Also, note that using a pipe or STDIN redirection will treat tabs as spaces, or disregard them entirely (if they appear at the beginning of a line). So I suggest using a filename as an argument if tabs are important either to the function or readability of the code.
* PRECEDENCE *
STDIN redirection has precedence, then piped input, then a filename as an argument, and finally text strings as an arguments.
In this example, the contents of file_as_stdin_redirection.txt would be uploaded. Both the piped_text and the file_as_argument.txt are ignored. If there is piped input and arguments, the arguments will be ignored, and the piped input uploaded.
* FILENAMES *
If a filename is misspelled or doesn't have the necessary path description, it will NOT generate an error, but will instead treat it as a text string and upload it.