Random Musings

The ps command in Linux has two main styles for options: dash-options and no-dash-options, each adhering to different standards:

Dash-Options (e.g., -e, -f)

• POSIX-compliant.
• Options are preceded by a single dash (-).
• Example: ps -e shows all processes.

No-Dash-Options (e.g., aux)

• BSD-style syntax.
• Options are not preceded by a dash.
• Example: ps aux shows all processes with additional user and memory details.

Key Difference

• Dash-options often require options to be combined or separated explicitly (-ef).
• No-dash-options are generally more concise but less portable across UNIX variants.

Can I use ps -aux?

You can use ps -aux, but it is not technically correct and may produce unintended results:

• -a, -u, and x are BSD-style options. They should be used without a dash, as in ps aux.
• Using -aux invokes POSIX-style syntax, which may cause ps to interpret -u as an invalid user name depending on the system.

Correct Usage:

• For BSD-style: ps aux
• For POSIX-style: ps -e or ps -ef

It’s recommended to follow the correct style for clarity and portability.

Can you make an extensive list of ps with dash and no-dash options

Here’s an extensive list of common ps options categorized by dash (-) and no-dash usage styles:

---

With Dash (-): POSIX Style

Option	Description
-a	Show processes from all users (except session leaders).
-e	Display all processes. Equivalent to -A.
-f	Full-format listing, including user, PID, PPID, start time, and command.
-l	Long-format listing.
-u <user>	Display processes for a specific user.
-x	Include processes without a controlling terminal.
-p <pid>	Display specific processes by their process IDs (PIDs).
-o <fields>	Specify output format by selecting fields (e.g., PID, %CPU, %MEM).
-H	Show processes in a hierarchical tree view.
--forest	ASCII-art process tree for visualizing relationships.

---

Without Dash: BSD Style

Option	Description
a	Show all processes for all users (interactive and non-interactive).
x	Include processes without a controlling terminal.
u	Display user-oriented output format.
ax	Show all processes regardless of terminal association.
aux	Display all processes with detailed information (user, CPU, memory usage).

---

Key Differences

1. Dash Style (-): Follows POSIX conventions; options can be combined (e.g., -ef) or written separately.
2. No-Dash Style: Follows BSD conventions; options are written together as a single string (e.g., aux).

Example Comparisons

• ps -e (POSIX): Display all processes.
• ps ax (BSD): Equivalent to ps -e, but shows all processes using BSD style.

For consistent cross-platform usage, POSIX style (ps -e, ps -f) is preferred, as not all systems support BSD syntax.