ssh + ksh + grep + wc - bash

Question

I'm trying to "ping" if some applications are running in some remote machines.
To do that I have a file with the servers and applications, like:
server1:application1
server2:application1
server3:application2
Etc.
I expect to obtain the number of applications with this name that are running in the server.
To connect and to check I need a ssh connection.
My script is a bash and is like this:
Ping_Applications () {
SetParam
cat $APPFILE | while read next
do
server=`echo $next | cut -d : -f1`
app=`echo $next | awk -F":" '{print $2}'`
commando="/bin/ssh $server '/bin/ps -fea | /bin/grep $app | /bin/grep -v grep | /bin/wc -l'"
eval COMA=\$\($commando\)
echo $commando
if [ $COMA != 0 ]
then
echo -e "$TIME : Application $app of on server $server is \E[32m[ RUNNING ]\E[0m";
else
echo -e "$TIME : Application $app of on server $server is \E[31m[ NOT RUNNING ]\E[0m";
fi
done;
}
My problem is that when I send
ssh $server 'ps -fea | grep $app | grep -v grep | wc -l'
This returns the number, but when is sent by using the script, I have not answer, because (I think) the pipe open a new shell.
I don't know how to solve this.
Any idea?
Thanks
Luis

Answer 1

This is Bash FAQ 50
You want to put the command in an array, and not use eval to invoke it:
commando=( /bin/ssh $server '/bin/ps -fea | /bin/grep "'"$app"'" | /bin/grep -v grep | /bin/wc -l' )
COMA=$( "${commando[#]}" )
commando is an array with 3 elements, so the last element can be passed to the remote server as a single word. Note the careful quoting around $app
Also, since $COMA will be a number, use numeric comparison: if [ $COMA -ne 0 ]

Answer 2

You might want to separate the /bin/ssh command and its arguments. Also put the "commando" in double quotes:
Instead of:
commando="/bin/ssh $server '/bin/ps -fea | /bin/grep $app | /bin/grep -v grep | /bin/wc -l'"
eval COMA=\$\($commando\)
Try this:
commando="/bin/ps -fea | /bin/grep $app ..."
/bin/ssh $server "$commando"
Bash variables gets expanded in double quotes, but not in single quotes.

Answer 3

Thanks for your help
I mixed the answers from Eric Renouf and Glenn Jackman and the solution es like this:
Ping_Applications () {
SetParam
cat $APPFILE | while read next
do
server=`echo $next | cut -d : -f1`
app=`echo $next | awk -F":" '{print $2}'`
commando=( /bin/ssh $server '/bin/pgrep -f "'"$app"'" | /bin/wc -l' )
COMA=$( "${commando[#]}" )
if [ $COMA -gt 0 ]
then
echo -e "$TIME : Application $app of on server $server is \E[32m[ RUNNING ]\E[0m";
else
echo -e "$TIME : Application $app of on server $server is \E[31m[ NOT RUNNING ]\E[0m";
fi
done;
}
Now i have a different problem:
This solution works, but only for the first input, then the script stops.
I have around 10 different applications in my $APPFILE, but only the first one is executed.
Regards.
Luis