pkill -signal usr2 someprocess
pkill: invalid session id: ignal
From the output the command is unable to interpret -signal, actually the command should look something like:
pkill -SIGUSR2 <process name>
Am not sure if USR2 signal is available, you can check that by running the following command:
If it show that as available then you can use it.
Let me give you an example:
1. dd if=/dev/zero of=/dev/null & (it will start the DD process in background)
2. To kill it using pkill you can run: pkill -SIGKILL dd , where -SIGKILL is the signal, you don't have to use -signal to mention the signal, just use "-" with kill signal.
EDIT: I misunderstand usr2, Gazl is right it should be SIGUSR2