My hotplug isn't hotplugging.  Despite reassuring beeps, the pcmcia card does
not come up when it should.  Manually running 'ifup eth0' works.

Further investigation revealed this is what happens each time /sbin/ifup runs
grep, when it is kicked off by /etc/hotplug/net.agent:

execve("/bin/grep", ["grep", "eth0"], [/* 7 vars */]) = 0

...

close(1)                                = -1 EBADF (Bad file descriptor)
write(2, "grep: ", 6)                   = -1 EBADF (Bad file descriptor)
write(2, "write error", 11)             = -1 EBADF (Bad file descriptor)
write(2, ": Bad file descriptor", 21)   = -1 EBADF (Bad file descriptor)
write(2, "\n", 1)                       = -1 EBADF (Bad file descriptor)
_exit(1)                                = ?


Looks like there's no stdout or stderr.

As a temporary fix, adding

exec 1>/dev/null

to /sbin/ifup gets hotplug working again.  Not sure if this is the right fix.