How to Open Multiple Instances of a Program in Linux

How to open multiple instances of a program in Linux

It is specific to gedit. You are likely looking for gedit --new-window &.

From man gedit:

--new-window
       Create a new toplevel window in an existing instance of gedit.

Okay to run multiple instances of the same executable?

Running multiple instances of a same executable doesn't cause any issues. In the eyes of operating system they are two different processes. Each instance have their own page tables, file descriptors, stack, PID etc.., which are independent of all other instances.

But when you are accessing a same resource on different processes then you have to synchronize the resource access by using any of the lock strategies. For example two instances writing to a same file will result in clutters in the file where one instance could possibly write in the middle of an another instance's data.

Two instances reading from a same file won't be a problem, but when one writes and other reads the result will be messy. Note: Each instance will have their own read/write pointer where they are reading/writing independent of other instances.

As you are using the file dataToRead.dat purely for reading you won't get any issues.

Overall there is no issue in running multiple instances if you have properly synchronized the resource access.

Running multiple instances of a shell function parallelly

I think you could update your script as follow:

#!/bin/bash

myfunc() {
   job_id=$1
   echo "Started job ${job_id}..."

   #do something (call a rest service)
   sleep 300
   status=$(get status of the operation performed above)
   while [ "$status" != "succeeded" ]; do
       #do something (call a rest service)
       sleep 300
       status=$(get status of the operation performed above)
   done

   echo "Terminated job ${job_id}."
}

a=0

while [ $a -lt 1000 ]
do
   echo $a
   a=(($a + 1))
   myfunc $a &
done

wait
echo "Parallel execution terminated."

How to make a bash script that creates 40 simultaneous instances of a program?

You can use a loop and start the processes in the background with &:

for (( i=0; i<40; i++ )); do
   php /home/calculatedata.php &
done

If these processes are the only instances of PHP you have running and you want to kill them all, the easiest way is killall:

killall php

How do you run multiple programs in parallel from a bash script?

To run multiple programs in parallel:

prog1 &
prog2 &

If you need your script to wait for the programs to finish, you can add:

wait

at the point where you want the script to wait for them.

Run multiple instances of gtkmm applications under linux

You have to pass the APPLICATION_NON_UNIQUE value from ApplicationFlags using the set_flags() method of your application.

Running multiple instances of a program at one time c++

Just start 3 processes, for example:

for(int i = 0; i < 3; i++)
  system("path_to_your_program");

It starts command in system command processor(bash/cmd.exe/etc).
Or use system calls.

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