uses both shell and python codes in one script.
On 2019-10-04 09:15:41 +1000, Chris Angelico wrote:
> On Fri, Oct 4, 2019 at 9:08 AM Cameron Simpson <cs at cskk.id.au> wrote:
> > On 03Oct2019 23:55, Chris Angelico <rosuav at gmail.com> wrote:
> > >In the shell, the first two are an empty string, then ':' is a
> > >colon, which introduces a label (the fact that it's in quotes is
> > >irrelevant to the shell). So there's an empty label followed by a
> > >shell comment.
> > No. ":" is a synonym for "true". (Like "[" is a synonym for "test".)
> > There aren't labels in the shell. This is just a dummy "true" command,
> > with a comment.
> My bad. I remember using a leading colon-space as a multi-shell
> comment, and in at least some of them, it's a label
You may actually be onto something here. I came across this interesting
GOTO, : (v2 pages 37-38)
Goto manipulated the standard input to give the illusion of a
programmable shell (Thompson, v2) The associated : command, which
thanks to ASCII collating sequence boasted the first page in the
manual, was a big nop.
It doesn't explicitely say what : was used for, but since it was
associated with goto, it was very likely used to mark a label.
The Bourne shell, introduced with v7, doesn't have goto, but retained :
as a no-op.
 To Unix history afficionados.
_ | Peter J. Holzer | we build much bigger, better disasters now
|_|_) | | because we have much more sophisticated
| | | hjp at hjp.at | management tools.
__/ | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
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