Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!mcvax!hp4nl!philmds!leo
From: leo@philmds.UUCP (Leo de Wit)
Newsgroups: comp.unix.wizards
Subject: Re: shell script puzzler
Keywords: /bin/sh
Message-ID: <998@philmds.UUCP>
Date: 8 Apr 89 09:49:24 GMT
References: <995@etnibsd.UUCP> <16489@mimsy.UUCP> <3286@ttrdc.UUCP>
Reply-To: leo@philmds.UUCP (Leo de Wit)
Organization: Philips I&E DTS Eindhoven
Lines: 35

In article <3286@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes:
    []
|If you want to see that pid at the END of the subshell, just
|
|(
|...
|exec echo '$$'
|#nothing from here on will be executed
|...
|)

Script started on Sat Apr  8 11:30:51 1989
philmds> (exec echo '$$')
$$
philmds> ^D

script done on Sat Apr  8 11:31:20 1989

A pid of '$$'? C'mon 8-).

What you can do:

	 $ (eval echo '$$')  # or perhaps just (echo $$)

but this will evaluate to the parent's pid (since $$ is set only once,
in the parent; the child is just a forked off copy).
Alternatively,

	 $ sh -c "echo \$\$"

does give its pid correctly. Note however that this requires an exec,
and does not preserve the current shell's context (like shell variables
etc.).

	 Leo.