Monitor CPU/Memory usage of remote Linux machines

Question

I have done some research but I have not found a good solution yet. I am looking for a simple program which shows me CPU/memory usage of remote Linux (Slackware) machines (20-30) to which I can login via passwordless ssh. I do not want to install any software on the machines. I just want something like: - ssh into every machine - run e.g. top - return reduced output (only CPU/memory usage) - nicely align this into a table - update the status every e.g. 2 seconds

I do NOT need to log anything or get any notifications of events. I just want this program for quick checks.

I already found the program "dtop" from clusterit but it won't run on my machine (Ubuntu 16.04) - giving me seg faults. And it does not seem to be maintained any longer (https://github.com/garbled1/clusterit).

I would be happy for any recommendations! Thanks in advance!

Answer 1

So I hacked together a solution from various places, which works for me. I actually forgot, which sources I used - please tell me, if you feel I should link a post/website! I use the following script.

#!/bin/bash 

input=$1

declare -a addresses
declare -a cpu_last
declare -a cpu_last_sum
declare -a cpu_usage

# read in the list of addresses to ssh in
i=0
while IFS= read -r line
do
  addresses[$i]=$line
  i=$i+1
done < "$input"


while :; do
  for i in "${!addresses[@]}"; do

    # Get the first line with aggregate of all CPUs 
    cpu_now=($(ssh ${addresses[$i]} head -n1 /proc/stat)) 

    # Get all columns but skip the first (which is the "cpu" string) 
    cpu_sum="${cpu_now[@]:1}" 
    # Replace the column seperator (space) with + 
    cpu_sum=$((${cpu_sum// /+})) 
    # Get the delta between two reads 
    cpu_delta=$((cpu_sum - cpu_last_sum[$i])) 
    # Get the idle time Delta 
    cpu_idle=$((cpu_now[4]- cpu_last[$i])) 
    # Calc time spent working 
    cpu_used=$((cpu_delta - cpu_idle)) 
    # Calc percentage 
    cpu_usage[$i]=$((100 * cpu_used / cpu_delta)) 

    # Keep this as last for our next read 
    cpu_last[$i]="${cpu_now[4]}"
    cpu_last_sum[$i]=$cpu_sum 
  done

  # print the results
  for i in "${!addresses[@]}"; do
    printf "${addresses[$i]}: ${cpu_usage[$i]}     \n"
  done

  # Wait a second before the next read
  sleep 1 

  # clear the previous lines
  for i in "${!addresses[@]}"; do
    tput cuu1 # move cursor up by one line
  done


done

There is probably lots of room for improvements. I would be thankful for any suggestions!