Processes
Displaying alive processes
The simplest way to get the list of running processes is to use the ps
command:
$ ps
PID TTY TIME CMD
1866 pts/0 00:00:00 bash
2247 pts/0 00:00:00 ps
In this example, there are only 2 processes running:
- bash (the shell interpreter)
- ps
Importantly, the first column is the process id (or PID), which is be useful when it comes to kill the process (see next section).
The top command displays all running processes with associate resources.
Similarly, htop does the same thing in a prettier fashion.
Stopping a process
When running a series of analyses which take some time, it may be useful to stop it if, for example, we notice an mistake in the script.
If the job is running in foreground, you can stop it by hitting Ctrl-C.
If the job is in background or runs in another terminal, you will have to
kill it with the command kill [options] PID, with PID the process id.
You can also kill a process using its name with killall [options] PROCNAME.
Importantly, and as its name suggests, this tool will kill all processes
named PROCNAME.
Meaning that you cannot use this tools to kill only one instance of a program
if you have multiple instances running (you have to use kill instead).