Rakib Fiha's questions

I have moreutils installed which provides /usr/bin/parallel, which is not useful for me. If I now want to install the parallel package (GNU Parallel) I have learnt from this answer that it would rename the existing /usr/bin/parallel of moreutils to /usr/bin/parallel.moreutils.

I was wondering what would happen if the opposite is done. For example, I have the parallel package installed and later on someone uninstalls moreutils and then reinstalls it again, will it rename /usr/bin/parallel to /usr/bin/parallel.gnu or what name would it get?

And if it does the renaming, how to avoid that?

My current Ubuntu version is:

$ lsb_release -a
No LSB modules are available. 
Distributor ID: Ubuntu 
Description: Ubuntu 18.04.3 
LTS Release: 18.04 
Codename: bionic

I also use Ubuntu 16.04 on other machines.

I am running some query commands in remote host with xargs in parallel which is working efficiently and very well but I have some problem in finding in which host I am getting the query from.

Right now the part of the script which is doing it, looks exactly like this:

export commands="cmd1; cmd2; "
hosts=("host1" "host2" "host3" "host4")
MaxInstance=10
echo_var(){
   echo "Executing in $1:"; sleep 1; echo "Output of: $commands"; return 0;
}
export -f echo_var
printf "%s\n" ${hosts[@]} | xargs -n 2 -P $MaxInstance -I {} $(command -v bash) -c 'echo_var "$1"' _ {}

which should output like the following because of sleep 1:

Executing in host1:
Executing in host2:
Executing in host3:
Executing in host4:
Output of: cmd1; cmd2; 
Output of: cmd1; cmd2; 
Output of: cmd1; cmd2; 
Output of: cmd1; cmd2;

To achieve the output that may look similar to the one shown at the end, I would have to edit the existing functions to the following to get closer to what I wanted. But even here if I use printf "%s\n%s" "$name" "$output" , it breaks sometimes at the new line. For example:

echo_var(){
 name="Executing in $1:"; sleep 1; output="Output of: $commands";
 echo -e "$name: $output" ## will work
 # echo -e "$name\n$output" ## will not work or even
 # printf "%s\n%s" "$name" "$output" ## will not work
 return 0;
}

Without sacrificing the rapidness of parallel execution, I would like to have the output like the following. Is there any option in xargs to specify to show the output of the entire instance at a time?

Executing in host1:
Output of: cmd1; cmd2;
Executing in host2:
Output of: cmd1; cmd2;
Executing in host3:
Output of: cmd1; cmd2;
Executing in host4: 
Output of: cmd1; cmd2; 

This following message shows up whenever I login via ssh.

  System load:  0.23               Processes:           163
  Usage of /:   24.1% of 58.39GB   Users logged in:     0
  Memory usage: 27%                IP address for eth0: 192.168.100.82
  Swap usage:   0%    
 * MicroK8s is Kubernetes in a snap. Made by devs for devs.
   One quick install on a workstation, VM, or appliance.   
Current zen blocks are synced at 
Last login: Wed Dec  5 09:52:41 2018 from 192.168.100.71

I added some script at /etc/update-motd.d/ to add some more message that I need it show whenever there is an ssh login.

When I run run-parts /etc/update-motd.d/ it works fine like following output:

+ printf Current zen blocks are synced at "blocks": 424076,

But when I exit and login again the message does not show up. Output below:

Current zen blocks are synced at

here is what I have added

#!/bin/sh
set -x
printf "Current zen blocks are synced at $(/usr/bin/zen-cli getinfo | grep blocks)"