How to grep success in a for loop - loops

Question

Struggling with this...
for i in `cat services.txt`
do
if ! grep -q $i; then
echo " $i Is NOT Running"
else
echo " Checking $i on `hostname`..."
ps aux | grep -i $i | awk '{print $1, $11}'| cut -d' ' -f1-2| sort
echo -e " "
sleep 4
fi
done
The block just hangs - Ive not been able to capture the success/failure of grep
If a string in services.txt is NOT found ... the script hangs... Id like for grep to skip it if not found
services.txt contain just single words
thanks!

Answer 1

The reason your script hangs is beacuse the command grep -q $i is waiting for an input. You can try running that command separately in a shell and verify that it prompts for an input.
Changing your command to ps aux | grep -i $i in the if statement should fix your issue.
NOTE: ps aux | grep -i $i lists grep also as one of the process. Make sure you exclude that process by piping it to another grep ps aux | grep -i $i | grep -v 'grep'

Answer 2

here is the working code
checkservices() {
cat >$HOME/services.txt <<EOF
ganglia
hbase
hdfs
hive
hue
livy
mapred
test-missing-service
mysql
oozie
presto
spark
yarn
zeppelin
EOF
for i in `cat $HOME/services.txt`
do
if `ps -ef | grep ^$i | grep -v grep >/dev/null`
then
i=$(echo "$i" | awk '{print toupper($0)}')
echo "$i -- is running on `hostname`"
echo ""
sleep 2
else
i=$(echo "$i" | awk '{print tolower($0)}')
echo "$i -- IS NOT running on `hostname` error"
echo ""
fi
done
}