On 03/25/2010 01:32 PM, Siddhesh Poyarekar wrote: > In a terminal, execute a script which does basically this: > > trap '' SIGTERM > ... > bash > > According to the above explanation, the resultant bash prompt I get on > execution of this script will allow me to override the ignored SIGTERM > since it was set in its non-interactive parent.
No. In that case, you ended up with an interactive shell, where POSIX is silent on the expected behavior. Or, put another way, by stating nothing explicit about interactive shells, POSIX has implicitly stated that the resulting bash prompt MAY, but not MUST, allow you to override the ignored SIGTERM, and that you, as the interactive user, have no guarantees on which behavior was chosen by bash. On the other hand, change that last line to 'bash ./program', where './program' is a bash script, and then POSIX is clear that ./program MUST be prohibited from changing SIGTERM because it is non-interactive and inherited an ignored SIGTERM. > So any signal that GETORIGSIG is called for and is inherited as > ignored from parent will automatically be hard ignored. Yes. POSIX requires this for non-interactive shells, and does not forbid it for interactive shells. Technically, this code could be modified to exempt interactive shells from hard-ignores, or left as is by treating both classes of shells identically in keeping things hard-ignored; either approach still meets POSIX. -- Eric Blake ebl...@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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