Processes

The Processes screen lists everything running on your computer, refreshed every sampling interval (one second by default). It opens as a table and switches to a tree when you want to see which process started which.

What each process shows

Field	Details
PID and parent PID	The process ID and the ID of the process that started it
Name and command line	The executable name and the full command it was started with
User	The account the process runs as
Status	Running, sleeping, stopped or zombie
CPU	Current usage and a rolling average, so a brief spike doesn’t hide a steady load
Memory	Resident memory (actually in RAM) and virtual memory (address space reserved)
Started and running for	Launch time and how long it has been running
Threads and open files	Thread count and open file descriptors (handles on Windows)
Priority	Nice value on macOS and Linux, priority class on Windows
Executable path	Where the program file lives on disk

Sort by any column, filter the list and search to narrow it down. Rows that use a lot more CPU or memory than the rest of your system get a subtle red tint. The threshold is relative to what else is running, so on a busy machine only the real outliers stand out, and on an idle one a moderate process still catches your eye.

Tree view

The tree view shows parent and child processes with indentation and connecting lines. Collapse a branch to hide a browser’s dozens of helper processes behind one row, or expand it to find the one tab process that’s misbehaving.

Process details

Select a process to open its detail panel:

• every field above, including the full command line
• a graph of the last 60 seconds of its CPU and memory use
• the files it has open
• its open network connections, with the same data as the Network screen

Some details belong to other users or to the system. macOS, Linux and Windows restrict what an ordinary user may read from those processes, typically open files and sometimes the command line. Sentinel shows these fields as not available instead of leaving them blank or guessing.

Actions

Every action opens a confirmation that restates the process name and PID and says exactly what will happen before you choose.

Action	macOS	Linux	Windows
End process	Asks apps to quit normally, otherwise sends SIGTERM	Sends SIGTERM	Asks the process’s windows to close; a process with no windows is ended with TerminateProcess, and the confirmation says so
Force kill	SIGKILL	SIGKILL	TerminateProcess
Change priority	Sets the nice value	Sets the nice value	Sets the priority class
Reveal executable	Selects it in Finder	Opens your file manager at it	Selects it in File Explorer
Copy command line	Copies the full command to the clipboard	same	same

End process gives the program a chance to save and clean up. Use Force kill only when a process ignores that request; it stops immediately and loses anything unsaved.

On macOS and Linux, lowering a process’s nice value (giving it more priority) requires root. Lowering its priority works for your own processes.

When the process changes under you

Process IDs are recycled. If a process exits while the confirmation is open, the operating system can hand its PID to a completely different program. Sentinel guards against killing the wrong one:

• When it prepares the action, Sentinel records the process’s identity, including its start time.
• When you confirm, it checks again. If the process is gone, you get “process not found”. If the PID now belongs to a process with a different start time, you get “process changed” and nothing is sent.
• A prepared action expires after five minutes. Confirming an expired one asks you to start over.

You can see the result of every attempt, including refused ones, on the Activity screen.