Message-ID: <4B8DC616.9020302@columbus.rr.com>
Date: Tue, 02 Mar 2010 21:14:46 -0500
From: Paul McFerrin <pmcferrin AT columbus DOT rr DOT com>
Reply-To: pmcferrin AT columbus DOT rr DOT com
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To: Cygwin <cygwin AT cygwin DOT com>
Subject: pipes are still buggy in 1.7
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Hi folks:

I've been tryinh to get the following code to work.  What I trying to do 
is to run a ps command 2 times (with 3 secs separation) and have the awk 
program capture the output kill all processes for a shutdown script.  
Something is hanging.  It does not run and control-C & controol-\ does 
not work.  Here is the script:
.$ cat /lbin/shutdown
#!/bin/bash
#
#       Shutdown the cygwin system
#
#       First we send SIGKILL to all process NOT in our process
#       group.  Then after a 5-second sleep, we send SIGKILL.
#
#       The last step is to kill off our process group.
#
#       Written: Paul E. McFerrin  02/15/02
#

ME=`basename $0`
TMP=/tmp/${ME}_tmp # generated script name
 >$TMP
if [ -z "$CONSOLE_TTY" ]
then
        echo "You must execute $ME in the console (first) window!!"
        exit 2
fi
echo -e "\nShutting down CYGWIN ..."
PATH=/usr/local/apache/bin:$PATH
if [ -f /usr/local/apache/bin/apachectl ]
then
        apachectl stop
fi
AWKPGM='
#     PID    PPID    PGID     WINPID  TTY  UID    STIME COMMAND
#  442949       1  442949 4294461843    0  500 02:35:28 /usr/bin/KSH
#  652513       1  652513 4294323867    0  500 02:35:43 /usr/bin/RXVT
/PID/ { next }
{
        if( $1 == pid ) {
                ourpgrp = $3
        }
        pgroup[$3 ""] = $3
        #next
}
{
        nonspec[$1 ""] = $1
}
END {
        print "exec 2>/dev/null" >TMP
        print "# Our process group = " ourpgrp >>TMP
        for( g in pgroup ) {
                if( g != ourpgrp ) {
                        print "echo + kill -15 -" g >>TMP
                        print "kill -15 -" g >>TMP
                }
        }
        print "sleep 5" >>TMP
        for( g in pgroup ) {
                if( g != ourpgrp ) {
                        print "echo + kill -9 -" g >>TMP
                        print "kill -9 -" g >>TMP
                }
        }
        print "# killing off our process group" >>TMP
        for( g in pgroup ) {
                if( g == ourpgrp ) {
                        print "echo + kill -9 -" g >>TMP
                        print "kill -9 -" g >>TMP
                }
                print "echo + kill ALL -9 1 " >>TMP
                print "kill -9 1" >>TMP
        }
        print "# killing off remaining processes, if any" >>TMP
        for( pid in nonspec ) {
                if( pid != $1 ) {
                print "echo # nonspec = " pid >>TMP
                # kill all other processes, except for me
                        if (NF == 8) {
                                print "echo + kill -9 " pid >>TMP
                                print "kill -9 " pid >>TMP
                        }
                }
        }
}'
if [ -p /tmp/pipe1 ]
then
        rm -f /tmp/pipe1
fi
mknod /tmp/pipe1 p
exec 1>/tmp/pipe1   # keep shell opened into pipe1
gawk "$AWKPGM" TMP=$TMP pid=$$ </tmp/pipe1
ps -a >/tmp/pipe1
sleep 3
ps -a >>pipe1
1>&-    # now we close the pipe1
rm -f /tmp/pipe1
if [ -s $TMP ]
then
        trap '' 15 # shields up!
        #/bin/sh $TMP
cat $TMP
fi
# in theory, the exit should not be reached as we should have been killed
exit 0


Is this a bug in pipes??

- Paul

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