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Full Discussion: Running function or command concurrently in a bash script
Top Forums Shell Programming and Scripting Running function or command concurrently in a bash script Post 302283869 by dj_bridges on Wednesday 4th of February 2009 09:19:44 AM
Old 02-04-2009
Otheus thanks for the rapid response. Yes you are right - I just want the script to constantly monitor the connection and start it again if it stops.

So if I run the script that you gave me it looks for the tunnel-keepalive.pid in /var/run, but nothing by this name appears there. So the script will never enter the while loop. The script doesn't seem to run based on the existence of a file in the local directory. I can only get it to run if I do this:

Code:
LOCK=/var/run/tunnel-keepalive.pid
echo $$ >LOCK #Puts the pid into a file called LOCK
LOCK=./LOCK
# start tunnel here

while [ -f $LOCK ]; do
   # Test to see if tunnel is still up, if not: start again
   sleep 5
done

I know that the above works - if I delete the file LOCK then the while loop stops, but I feel like I am missing the point or pulling the pid into a file - or could I just use the presence of any old file to maintain the while loop (and therefore the tunnel)?

Sorry in advance for my ignorance.....
Last edited by otheus; 02-04-2009 at 10:22 AM.. Reason: space between $$ >
 

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LEARN ABOUT OSF1

iptunnel

iptunnel(8)						      System Manager's Manual						       iptunnel(8)

NAME

       iptunnel - Creates, deletes, and displays configured tunnels

SYNOPSIS

       /usr/sbin/iptunnel  [operation] [args]

DESCRIPTION

       The  iptunnel  command creates configured tunnels for sending and receiving IPV6 or IPV4 packets that are encapsulated as the payload of an
       IPV4 datagram.

       The iptunnel command can perform one of the following operations: Creates a tunnel interface, which  you  must  subsequently  configure	by
       using the ifconfig command. The syntax of the create operation is as follows:

	      iptunnel create [-I int-name] [v4-dest] [v4-src]

	      Specifies  the  interface unit of the tunnel to be created. This is an optional parameter.  The int-name parameter has the following
	      form: iptx, where x is the interface unit number. By default, the interface name selected for the tunnel is iptx+1, or the value	of
	      the  interface  unit  number  of the last tunnel created plus 1.	Specifies the remote end-point to which a tunnel is to be created.
	      Sets the IPV4 source address in the encapsulating header.  The tunnel is enabled (packets are sent/received on the tunnel)  only	if
	      v4-src  is  a valid address on the system.  This is an optional parameter.  Deletes a tunnel interface.  You must disable the tunnel
	      before you can delete it by executing the following command: # ifconfig tunnel name down	delete abort Shows the	tunnel	attributes
	      (name, tunnel end points, next hop for tunneled packets).

EXAMPLES

       To create a tunnel from hobbes to calvin, enter: # iptunnel create -I ipt5 calvin  ipt5  iftype 208 src 16.140.16.86 dst 16.140.16.91

       To display the tunnel attributes, enter: # iptunnel show ipt5 interface ipt5 src 16.140.16.86 dst 16.140.16.91 gate 16.140.16.86 To config-
       uring the tunnel to encapsulate IPv6 packets, enter: # ifconfig ipt5 ipv6 up

	      IPv6 packets will be sent as payloads of IPv4 datagrams from 16.140.16.86 to 16.140.16.91.

	      The tunnel may also be used to send IPV4 packets encapsulated within IPV4 headers as follows: # ifconfig	ipt5  10.10.80.60  netmask
	      255.255.255.0

	      To verify the previous command, enter: # ifconfig ipt5 ipt5: flags=4c1<UP,RUNNING,NOARP,MULTICAST>
		   16.140.16.86 --> 16.140.16.91
		   rxmt 1000, reach time 30000, dad tries 1, mtu 1280, hops 64, token len 64
		   inet 10.10.80.60 netmask ffffff00  ipmtu 1280
		   inet6  fe80::108c:1056  To  deleting the tunnel, enter: # ifconfig ipt5 down delete abort ipt5: delete inet address 10.10.80.60
	      10.10.80.60: aborting 0 tcp connection(s)

	      Then, enter: # iptunnel delete ipt5 interface ipt5 deleted

SEE ALSO

       Commands: ifconfig(8).

       RFC 2003, IP Encapsulation within IP, Perkins, C., October 1996

																       iptunnel(8)
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