Hey there! Let's break down exactly what ps -aux does, clarify each option, and fill in the gaps from your initial understanding—you're mostly on the right track, but there's a key correction and extra context to cover.

First, a quick overview: ps -aux is one of the most common commands on Linux/Unix systems for statically listing nearly every running process on the system. It combines three distinct options to deliver a detailed, user-focused view of process activity.

Let's break down each option individually:

• a option: You’re right that this shows "all processes," but more precisely, it displays all processes associated with any terminal—including those launched by other users, not just your own. On its own, ps a won’t catch background processes that aren’t tied to a terminal, though.
• u option: This isn’t just about "users"—it enables a user-oriented output format that adds critical context about each process. The output will include columns like the process owner (USER), CPU usage percentage (%CPU), memory usage percentage (%MEM), start time (START), and the full command/arguments used to launch the process (COMMAND). It’s far more detailed than the default ps output.
• x option: Your initial interpretation here was off—this doesn’t relate to "execution." Instead, x tells ps to display processes that aren’t attached to any terminal (tty). These are typically background system daemons (like network services or cron) or processes launched in the background without a terminal tie-in. Combining a and x ensures you see every process running on the system, terminal-associated or not.

Putting it all together, ps -aux gives you a comprehensive list of:

Every process from every user on the system, regardless of whether it’s tied to a terminal, displayed in a human-readable format that includes resource usage and ownership details.

One quick side note: You might sometimes see ps aux (without the dash) used interchangeably—this works too, as ps accepts both BSD-style (no dash) and System V-style (with dash) option formats for these flags.

内容的提问来源于stack exchange，提问作者John Friday