A till-end-of-line comment begins with a single slash that appears either –
- at the start of a non-empty line,
/ this line is ignored /so is this one
- is preceded by a space:
foo: 47; / this is also a comment 42+/1 2 3 / The first / does NOT start a comment!
In the last example, the first slash functions as the adverb over.
Begin a block comment with a lone backslash at the start of a line, and finish it with sole slash –
\ All of this is a block comment. Even /\ this is OK. / x: 47 / this line (before the slash) is code
or the reverse:
/ The opposite works, too. Using block comments to comment out code can be confusing unless you pick one way and stick to it. \
A \ does not have to be matched; it then serves as an end-of-file indicator:
\ all lines below are i g n o r e d
Lastly, if a script’s first line begins with ‘#!’, that line is skipped, e.g.:
#! blah.. blah..