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Path: utzoo!decvax!decwrl!pyramid!nsc!hplabs!sdcrdcf!curt
From: curt@sdcrdcf.UUCP (Curt Dodds)
Newsgroups: net.unix
Subject: Re: Can a trap survive an exec /bin/sh?
Message-ID: <2367@sdcrdcf.UUCP>
Date: Fri, 27-Sep-85 19:06:31 EDT
Article-I.D.: sdcrdcf.2367
Posted: Fri Sep 27 19:06:31 1985
Date-Received: Mon, 30-Sep-85 23:48:09 EDT
References: <668@ihu1h.UUCP>
Reply-To: curt@sdcrdcf.UUCP (Curt Dodds)
Distribution: na
Organization: System Development Corp. R+D, Santa Monica
Lines: 52
Keywords: trap .profile

In article <668@ihu1h.UUCP> takao@ihu1h.UUCP (John Takao Collier) writes:
>Is there a way to get a trap to survive the exec of the shell?
>What I want to do is set a trap, exec a shell, continue on with
>an interactive session in the exec'ed shell, and have the trap
>turned on in the exec'ed shell.
>
>This comes in handy if you want to set a trap in a .profile, but
>want to exec a new shell in the .profile.
>
>For example, if the following commands are invoked:
>
>trap 'echo bye' 0
>exec /bin/sh
>
>the trap disappears.
>
>I have tried various parameters to the shell, such as "-c" and "-i",
>but these experiments have failed, e.g.:
>
>exec /bin/sh -c 'trap "echo bye" 0'
>
>will exec the shell, read the string specified by the the "-c" parameter,
>reads the trap, then exits the exec'ed shell.  I do not want to exit
>the shell.
>
>If you have a solution, be it elegant or ugly, I would very much like to
>see it.
>
>Thanks.
>-- 
>
>---
>John Takao Collier   ..ihnp4!ihu1h!takao   1-312-979-3278
>AT&T Bell Laboratories,  Naperville-Wheaton Road,  Naperville,  IL   60566


Any time you do an exec you lose whatever you've done up to that point
(except the environment I suppose).

Sounds like what you want is the following:

--------------------------------------------------
trap 'echo bye;sleep 2;trap 0;exit' 0 1 2 3 15
/bin/sh
exit
--------------------------------------------------

If signals 1,2,3 or 15 occur while /bin/sh is running or if /bin/sh exits
the sequence of instructions within single quotes will be executed.
-- 
Curt Dodds
sdcrdcf!irdmega!curt


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