I recently tried naming two procs "mon" and "!mon".
In most cases executing !mon on the console executed mon.
It appears this is a feature of the history package,
however I'm not finding any mention of it in the manual page.
Does anyone know where it is documented?

daveb

clt.to.davebr@dfgh.net wrote:
> I recently tried naming two procs "mon" and "!mon".
> In most cases executing !mon on the console executed mon.
> It appears this is a feature of the history package,
> however I'm not finding any mention of it in the manual page.
> Does anyone know where it is documented?

The exclamation point for history expansion is used by GNU readline, so
if the history package is generally trying to emulate readline, that
would be where to look for documentation.

The docs for ! in the bash manpage are:

Event Designators
An event designator is a reference to a command line entry in
the history list. Unless the reference is absolute, events are
relative to the current position in the history list.

! Start a history substitution, except when followed by a
blank, newline, carriage return, = or ( (when the extglob
shell option is enabled using the shopt builtin).

On 12/26/2022 9:04 PM, clt.to.davebr@dfgh.net wrote:
> I recently tried naming two procs "mon" and "!mon".
> In most cases executing !mon on the console executed mon.
> It appears this is a feature of the history package,
> however I'm not finding any mention of it in the manual page.
> Does anyone know where it is documented?
>
> daveb
>

Good question. I could not find it documented in the Tcl manpages either.

Of course, the Unix shell pages document it so you could use that as a
(rough) reference. Still, this tclsh feature is not Unix-specific and
should probably be documented if it isn't.

/Ashok

On 26/12/2022 16:34, clt.to.davebr@dfgh.net wrote:
> I recently tried naming two procs "mon" and "!mon".
> In most cases executing !mon on the console executed mon.
> It appears this is a feature of the history package,

This is not a feature of the history package. It is the `unknown`
command that jumps in when a command line does not match an existing
command. So the behavior is described in the unknown man page:
"First, it sees if cmd has one of the following three forms: !!, !event,
or ^old^new?^?. If so, then unknown carries out history substitution in
the same way that csh would for these constructs."

However, if you have defined a !mon proc, then that should always be
found and the `unknown` command would not be invoked. I have no
explanation for the behavior you describe.

Schelte.