How to interrupt my script?
2014-04
I use the following script (which I start from at
command) as an alarm:
#! /bin/sh set -m while true; do paplay /usr/share/sounds/phone.wav done &
I want to bind a key to stop this alarm. Please help to write a script which could locate and kill this process.
Add the following to the end of your script:
PID=$!
echo $PID > /tmp/wakeupalarm.pid
Then your killing script will be
#!/bin/bash
PidFile=/tmp/wakeupalarm.pid
[ -f $PidFile ] && kill $(< $PidFile) && echo > $PidFile
You should also run the killing script at the start of the alarm script, to ensure a single instance of the process.
This should work
#!/bin/bash
pid=$(ps aux | grep scriptname.sh | awk -F ' ' ' { print $2 } '
kill $pid
I'm sure there are better ways though.
I have create a script to start a server(my first question). Now I want it to run on the system boot and start the defined server. What should I do to get this done?
My findings tell me put this file in /etc/init.d
location and it will execute when the system will boot. But I am not able to understand how the first argument on the startup will be start
? Is this predefined somewhere to use start
as $1
? If I want to have a case startall
that will start all the servers in the script, then what are the options I can manage.
My Script is like this:
#!/bin/bash
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
$0 stop
$0 start
;;
*)
echo "usage: $0 (start|stop|restart)"
;;
esac
/etc/init.d
is the script directory, in which the executable scripts appear. However, in order to run scripts in a particular order after your system starts, you need to add files to the /etc/rc#.d
directory. Entries that appear here tell your system in what order and at what run level scripts in /etc/init.d
should be run. The number after the rc indicates what run level the machine is running at, according to this chart:
http://en.wikipedia.org/wiki/Runlevel
So if you have:
/etc/init.d/importantscript
Then you need the (empty) files:
/etc/rc.d/rc3.d/S20importantscript
/etc/rc.d/rc6.d/K20importantscript
The S means start, and the K means kill. When your machine starts, the system will say "Ah, I'm running at RunLevel 3, let's pop over to rc3.d to see what scripts in '/etc/init.d' need to be run and in what order." In this case, the system will sort by 'S' and then the number after 'S' and will execute '/etc/init.d/importantscript start'. The 20 is just for ordering purposes... your script will run behind 'S19' and in front of 'S21'. You can create these files simply by doing:
sudo touch /etc/rc.d/rc3.d/S20importantscript
Here's a nice summary as well: http://www.linux.com/news/enterprise/systems-management/8116-an-introduction-to-services-runlevels-and-rcd-scripts
You don't have to --- and shouldn't --- create files in /etc/rc.d/rcN.d/
; what you should do instead is put a comment in your init script reading
# chkconfig NNN A B
where NNN
is the set of run-levels in which you want the script active (e.g., 345
if it's active in runlevels 3
, 4
, and 5
), and A
and B
are the start and stop priorities. Then chkconfig --add foo
(assuming your script is named foo
) will create the files in /etc/rc.d/rcN.d/
with the appropriate names.
You can then use service foo bar
to send the bar
message to your script (e.g., start
, stop
, whatever -- that's where your $1
comes from).
The $1 is the command line argument that is passed to your script, it is one of start, stop or restart. In Opensuse, I don't remember having an option to pass other arguments into the script when useing the runlevel editor thingy so I think that these are probably the only ones you should use.
I don't use Centos myself, but it seems that the program to control what is started at which runlevel is ntsysv.