Current instance of Shell ignoring SIGTERM Post: 302729691

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Top Forums Shell Programming and Scripting Current instance of Shell ignoring SIGTERM Post 302729691 by mirni on Saturday 10th of November 2012 10:38:27 PM

11-10-2012

Registered User

trap is used to trap signals within a *running script*. So while your script is running, it can catch a signal received (except for SIGKILL).
However, when you fork a new process from within your script it has its own PID with its own signals. So something like this won't do what you want:

Code:

#!/bin/bash

trap 'echo trapped' SIGTERM
/bin/bash -i  #will fork a new process, parent script keeps running and doesn't get to process the signal received until this child process is finished and flow returns to the script
echo Done #you won't see this until /bin/bash is finished. If this script  received a SIGTERM, you will see the trap message before "Done"

AFAIK it is not possible to catch a signal sent to a running executable, without inserting the trap into its source code and recompiling.

So what you see (guessing, since you never posted your code on how you are calling the shell and how you specify the trap), is that shell process is forked with its own PID, and parent script that you are calling it waiting for it to finish before it can process the signals. You can see that by running the example above.

mirni

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cpanplus::shell

CPANPLUS::Shell(3perl)					 Perl Programmers Reference Guide				    CPANPLUS::Shell(3perl)

NAME

       CPANPLUS::Shell - base class for CPANPLUS shells

SYNOPSIS

	   use CPANPLUS::Shell; 	    # load the shell indicated by your
					    # config -- defaults to
					    # CPANPLUS::Shell::Default

	   use CPANPLUS::Shell qw[Classic]  # load CPANPLUS::Shell::Classic;

	   my $ui      = CPANPLUS::Shell->new();
	   my $name    = $ui->which;	    # Find out what shell you loaded

	   $ui->shell;			    # run the ui shell

DESCRIPTION

       This module is the generic loading (and base class) for all "CPANPLUS" shells. Through this module you can load any installed "CPANPLUS"
       shell.

       Just about all the functionality is provided by the shell that you have loaded, and not by this class (which merely functions as a generic
       loading class), so please consult the documentation of your shell of choice.

BUG REPORTS

       Please report bugs or other issues to <bug-cpanplus@rt.cpan.org<gt>.

AUTHOR

       This module by Jos Boumans <kane@cpan.org>.

COPYRIGHT

       The CPAN++ interface (of which this module is a part of) is copyright (c) 2001 - 2007, Jos Boumans <kane@cpan.org>. All rights reserved.

       This library is free software; you may redistribute and/or modify it under the same terms as Perl itself.

SEE ALSO

       CPANPLUS::Shell::Default, CPANPLUS::Shell::Classic, cpanp

perl v5.14.2							    2014-09-29						    CPANPLUS::Shell(3perl)