Since the
interpreter is passed the filename containing the file, it is useful for
it to interpret the
hash sign (
#) as introducing a comment.
A short self-reproducing "program" in such systems (actually not properly a program, unless all executable files are considered one language) is
#!/bin/cat
This "script" copies itself when executed!
Store this in a file "self", then
chmod +x self. Executing
self will print the contents of the file.