Alternative network messaging? Post: 302721601

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Top Forums Shell Programming and Scripting Alternative network messaging? Post 302721601 by DGPickett on Thursday 25th of October 2012 02:53:23 PM

10-25-2012

Registered User

Yes, kill is named for it's most popular use, termination, but it is just a signal sender.

in shell, trap is the shell signal catcher. SIGINT was available, but for apps SIGUSR1 and SIGUSR2 are most appropriate: Man Page for signal (linux Section 7) - The UNIX and Linux Forums

The signal processing is done out of sequence with the process thread(s), but in the same process so variables are passed.

So, you can push files to input-dir/unique.take-me-extension, the final step being mv and then kill to start the possibly, usually sleeping server so it processes the input.(

Code:

ssh server_host 'cat >input-dir/unique.take-me-extension.tmp
  mv input-dir/unique.take-me-extension.tmp input-dir/unique.take-me-extension
  kill -SIGUSR1 `< server-pid-file`
 ' < input-file

Of course, you have to be the same id or root to signal a process. Named pipes can stall servers that only require the writer have permission on the pipe.

Code:

$ mknod p p
$ ls -lA|grep '^p'
prw-r--r--   1 my_uid    my_group          0 Oct 25 14:54 p
$ while :
do
 cat <p
done &
[1]     19299
$ echo hi >p
$ hi
echo hello >p
$ hello

Last edited by DGPickett; 10-25-2012 at 04:01 PM..

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LEARN ABOUT DEBIAN

if.conf

NETSCRIPT-2.2.conf(5)						File Formats Manual					     NETSCRIPT-2.2.conf(5)

NAME

       /etc/netscript/network.conf - interface, firewalling, and QoS configuration file.

       /etc/netscript/if.conf - interface setup shell script file

       /etc/netscript/qos.conf - QoS setup shell script file

       /etc/netscript/ipfilter.conf - IP chains filtering shell script file

       /etc/netscript/srvfilter.conf - server IP filter shell script file

DESCRIPTION

       This manpage is a place holder until something better is written when the netscript itself has stopped changing rapidly.

       Please  see  the README file in the /etc/netscript directory, and READ the configuration files if you need to change them.  Apart from net-
       work.conf, all of them contain sh (1) shell script functions which are there so that various things can be altered  or  hooked  in  at  the
       right place. Network.conf contains the full network setup details, including special interface setup for the likes of ciped/pppd/wanconfig,
       and is fully commented with examples given.

UPGRADE PATH FROM KERNEL 2.2.X
       The firewall/IP filtering stuff in ipfilter.conf is the part that changed radically with the move to iptables and a far better way of  set-
       ting  up  the  IP filtering rules, however the QoS and interface startup/shutdown in if.conf have changed but are backwards compatible with
       the old 2.2.x ipchains version of netscript for the interface address configuration settings.  You will have to set up the filtering  again
       to use iptables by directly using the iptables commands.

       Also,  the  kernel  2.2.x version scripts are set up so that iptables is only run on a 2.4.x kernel, otherwise IP forwarding is disabled if
       beforehand you set IPFWDING_KERNEL to FILTER_ON in network.conf.

       This means that when you upgrade a box to a 2.4.x router kernel, you should then be able to reboot it and log  into  remotely  and  upgrade
       netscript  to  the version that will support 2.4.x.  In this situation, if you have set old IPFWDING_KERNEL setting to FILTER_ON beforehand
       in network.conf, all IP forwarding through the box will also be disabled.  This means that you can safely remotely upgrade a firewall.

SEE ALSO

       netscript(8), ipchains(8), iproute(8), brcfg(8).

AUTHOR

       This manual page was written by Matthew Grant <grantma@anathoth.gen.nz>, for the Debian GNU/Linux system (but may be used by others).

BUGS

       The author is lazy.  He needs to write btter man pages...

								 November 23, 2000					     NETSCRIPT-2.2.conf(5)