checking information of different computers in a network using bash script - linux

Question

I am trying to write a bash script to access a file (nodeNames) that contains ip addresses to different computers in a cluster network, ssh into each of these computers and output some basic information namely: Hostname, Host IPaddress, load average and the process using the most memory and append all these information into a file seperating each wit commas. Also, each of the computers have same user and password. This is my code so far but it isn't working, please I need help here
egrep -ve '^#|^$'nodeNames | while read a
do
ssh $a "$#" &
output1=`hostname`
#This will display the server's IP address
output2=`hostname -i`
#This will output the server's load average
output3=`uptime | grep -oP '(?<=average:).*'| tr -d ','`
#This outputs memory Information
output4=`ps aux --sort=-%mem | awk 'NR<=1{print $0}'`
#This concantenates all output to a single line of text written to
echo "$output1, $output2, $output3, $output4" | tee clusterNodeInfo
done

Answer 1

You need to understand what is executed on which computer. The shell script you start is executed on your host A and you want information from your host B. ssh $a "$#" & will not suddenly make all the commands execute on the remote host B. Therefore, the
output1=`hostname`
will be executed on host A and output1 will have the hostname of host A.
You may also want to put the tee outside the loop or use tee -a to prevent overwriting your output file.
For bash, use $() instead of `` .
So, that would make your script:
egrep -ve '^#|^$'nodeNames | while read a
do
output1=$(ssh $a hostname)
#This will display the server's IP address
output2=$(ssh $a hostname -i)
#This will output the server's load average
output3=$(ssh $a "uptime | grep -oP '(?<=average:).*'| tr -d ','")
#This outputs memory Information
output4=$(ssh $a "ps aux --sort=-%mem | awk 'NR<=1{print $0}'")
#This concantenates all output to a single line of text written to
echo "$output1, $output2, $output3, $output4" | tee -a clusterNodeInfo
done
(have not tested it, but it should be something like this)