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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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how output ps aux | grep aUser and keeping Newline ? (lemmy.ml)

submitted 3 months ago by [email protected] to c/[email protected]

4 comments fedilink hide all child comments

Hi,

by doing a

ps aux | grep UserName

The output do not keep the LF[^1] 😡

I've found some solution online by they involve 3 or more pipe | !

On my side, I've made this

ps -fp $(pgrep -d, -u UserName)

But still I found it not super human readable.

Is their a native way with ps to filter users ? or to grep it but the keep the LF ?

[^1]: linefeed https://en.wikipedia.org/wiki/Linefeed#Representation

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[–] RavuAlHemio 8 points 3 months ago (1 children)

ps outputs a newline after every entry. What are you trying to accomplish?

Do you have a username that contains a newline character? If so… why?!

[–] [email protected] 3 points 3 months ago (1 children)

Security by overcomplication

[–] RavuAlHemio 2 points 3 months ago

Kinda hard to encode it in /etc/passwd, which separates entries with newlines and fields of an entry with colons.

Of course, you can activate some alternative user database in /etc/nsswitch.conf and then you can have your usernames with newlines in them, but at least half of the tools on your system that process usernames will take that personally…

[–] Para_lyzed 2 points 3 months ago* (last edited 3 months ago)

I'm not really sure what it is you're asking for here. As another commenter said, ps outputs a list of newline separated entries (using \n, the standard LF character). I even ran some sanity checks to make sure it wasn't using \r\n (CR LF) with the following:

$ ps aux | grep $USER | tr -cd "\n" | wc -m
14
$ ps aux | grep $USER | tr -cd "\r" | wc -m
0

The output of ps aux | grep $USER is consistent with the formatting of ps aux. I also found that ps aux | grep $USER was consistent with ps -fp $(pgrep -d, -u $USER) except that ps -fp $(pgrep -d, -u $USER) shows the header (UID PID PPID C STIME TTY TIME CMD), does not show the processes related to the command (entries of ps aux and grep --color=auto $USER), and does not show grep's keyword matching by highlighting all matches within a line. It is otherwise completely identical.

Can you provide the output that you are getting that is unsatisfactory to you? I don't think I can otherwise understand where the issue is.