Hi Ben,
Am 24.08.2009 um 03:04 schrieb Ben Walton:
I've discovered an interesting bit of solaris archaeology today and I
wanted to ask those with longer solaris memory why such a thing is
still supported.
Long before I ever encountered a shell, ^ was the symbol used to
separate commands in a pipeline. It seems that solaris' /bin/sh is
still allowing this in some cases. The following script demonstrates
it.
--snip--
#!/bin/sh
LESS=
export LESS
( echo test1
echo test2
echo test3 )^
/opt/csw/bin/ggrep 2
echo test^
/opt/csw/bin/less
--snip--
The word 'test2' is spit out by ggrep and the word 'test' is sent to
the stdin of less.
Can someone provide some history on this? It's fascinating (to me) as
a bit of lore from bygone days.
This is very interesting. /bin/sh seems to be the only shell
exhibiting this
behaviour, /usr/xpg4/bin/sh (the standard compliant shell) does not.
From O'Reilleys "Learning the BASH shell":
bash is almost completely backward-compatible with the Bourne shell.
The only
significant feature of the latter that bash doesn't support is ^
(caret) as a
synonym for the pipe (|) character. This is an archaic feature that
the Bourne
shell includes for its own backward compatibility with earlier
shells. No modern
UNIX version has any shell code that uses ^ as a pipe.
So, either the authors are not well informed, or Solaris 10 is not a
modern unix ;-)
After reading a bit more I learned that this was already in the
precursor of the Bourne
Shell, the "Thompson Shell" provided with Unix v4:
<http://en.wikipedia.org/wiki/Thompson_shell>
This must have been sometime after 1971, the year I was born 8-)
Best regards
-- Dago
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