[PLUG] what does &(...) do?

[Denis Heidtmann]

On Thu, Feb 16, 2012 at 5:38 AM, Michael Rasmussen <michael at jamhome.us> wrote:
...
> I don't _know_ what that does. Lack of punctuation based searching in impeding my efforts to look it up.
> Having had to work last night (jobs are useful but sometimes ...) prevented me from experimenting.
>
> So I asked.
>
> --
>            Michael Rasmussen, Portland Oregon

knowing virtually nothing about bash, I searched the Bash Reference
Manual.  I got 80 hits for & ; none for &( .  Does this apply? (I can
say that the Bash Reference Manual is as opaque as Bash itself.)

HISTIGNORE
A colon-separated list of patterns used to decide which command lines
should be saved on the history list. Each pattern is anchored at the
beginning of the line and must match the complete line (no implicit
‘*’ is appended). Each pattern is tested against the line after the
checks specified by HISTCONTROL are applied. In addition to the normal
shell pattern matching characters, ‘&’ matches the previous history
line. ‘&’ may be escaped using a backslash; the backslash is removed
before attempting a match. The second and subsequent lines of a
multi-line compound command are not tested, and are added to the
history regardless of the value of HISTIGNORE.
HISTIGNORE subsumes the function of HISTCONTROL. A pattern of ‘&’ is
identical to ignoredups, and a pattern of ‘[ ]*’ is identical to
ignorespace. Combining these two patterns, separating them with a
colon, provides the functionality of ignoreboth.

-Denis