I’m writing a short bash script that involves logging into roughly 100 nodes and counting the number of processes running in top with my username, and I’m trying to combine the ssh-related processes all into one bundled command:
ssh server-1 top -bn1 | grep 'program' | grep -c 'username'
When I do this, I notice that it takes roughly 5 seconds to return the process count for a server, which is not long by itself. However, when I want to run this command about 100 times, it would be desirable to speed it up. I can edit my .bash_profile to comment out the following lines:
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
From there, I can complete the process of entering the ssh, top/grep/grep, and exit commands by hand in about 3 seconds. Given that the ssh and exit processes only take about 1 second combined (with my .bash_profile commented out) and that the top/grep/grep is nearly instant, it should be significantly faster than 3 seconds if the computer does the commands. However, keeping the .bash_profile commented out does not improve the speed of the bundled ssh command and the bundled command still takes about 5 seconds vs. 3 seconds doing it by hand. Can anyone explain why the bundled command is slower than doing the commands individually by hand, even when the .bash_profile is commented out?
