5 Jan
2020
5 Jan
'20
7:45 p.m.
On Sat, Jan 04, 2020 at 09:41:59PM -0500, Chet Ramey wrote:
concerning "interactive" I think instead of the V7 sh you rather have
the BSD sh in mind here.
V7 sh didn't know # at all. At ATT it came with SysIII (both modes).
And keep in mind, stty erase defaulted to # on V7, even until SySV (and 3BSD),
and this character wouldn't have been handy anyway. 4+BSD changed this.
4.1BSD implemented #, and 4.3 BSD changed it to "non-interactive only".
(And all this is not to be confused with the # hack to exec to csh on 3+BSD,
only if it's the first character in a script.)
BTW, an academic yet funny example of : side effects is this
: `echo output 1>&2`
Sven
On 1/4/20 6:53 PM, Dave Horsfall wrote:
Which reminds
me: which Shell introduced "#" as a true comment?
Define "true comment." The v7 shell had `#' as the comment character, but
it only worked when in non-interactive shells. I think it was the Sys III
shell that made it work when the shell was interactive.
This is, incidentally, why bash has the `interactive_comments' option,
which I saw in another message. BSD, which most of the GNU developers were
using at the (pre-POSIX) time, used the v7 shell and didn't have
interactive comments. When a sufficiently-advanced POSIX draft required
them, we added it.