Explainshell and dangerous commands of Linux

!!! · 12-17-2017, 12:45 PM

Quote:

Originally Posted by !!!

Edit note added: I'm slow: I started compsing this while Thread on ZRT.

Hello my friend!!! Remember LQ is for more of Q&A, than discussions,
Especially possibly controversial discussions. I hope my suggestion of:
reddit (For more like 'social chat') isn't against LQ rules.

Yes, there's tons of 'damaging' cmds in any os, depending on privs.
That's why I suggested mll. Did you try it, in your VBox? Slackware?
I suggest mimimal Slackware installs, VBox 'snapshots'
Or much easier with mll, because you have only the cd, no hdd!!!

Tell us something we can reproduce, that didn't give the result you expected,
and the exact result differnce. Best wishes for comfort&fun, in all of Life

Edit append: more: @pn: I have a useful question/project for you:
Using mll in a 128MB VBox (no .vdi), with your CPU, how many seconds before it is 'wedged' to the point that Ctrl+c won't work? My N270: a few I think I remember; your cpu probably faster. What ulimit will 'nicely' prevent this? What echo > /{sys,proc}/... ?
Write a nice tutorial about: what reasonable&useful 'setting' could stop a fork bomb, without blocking any other 'reasonable' things?

@pn: Again, you are breaking my heart, by ignoring me!!! I need a friend, and asked you nicely. But you ignore me, and just consume all the 'food' you receive from all the others!

Please: 'HELP ME'!!! Or Jeremy will get mad again (probably at both of us) unless we produce some interesting&useful Q&A. Thank you & best wishes always.

p.s. Edit append: @pn: See, this is for reddit:
https://www.reddit.com/r/linux/comme...on_a_mistyped/
More @pn: could you please write a LQblog tutorial for me, on creating the 'docker' of that. Thanks.

Quote:

Update 2017-07-04
Suicide Linux is now a Docker image. Here's the source.
docker run --rm -it -t tiagoad/suicide-linux

Code:

/ # echo '#root::0:0::/:/bin/sh'>/etc/passwd
/ # id
uid=0 gid=0
/ # cat /etc/passwd
#root::0:0::/:/bin/sh
/ # ls -l /etc/passwd
-rw-r--r--    1 0        0               22 Dec 10 00:16 /etc/passwd
/ # rm -rf / 2>/dev/null
/ # ls -l /etc/passwd
ls: /etc/passwd: No such file or directory
/ # id
uid=0 gid=0
/ # pwd
/
/ # ls -la
total 0
/ # uname -a
Linux minimal 4.4.44 #1 SMP Fri Jan 20 21:34:35 EET 2017 i686 GNU/Linux
/ # ps |egrep -v ']|dhcp|sh$'
PID   USER     TIME   COMMAND
    1 0          0:09 init
 3187 0          0:00 ps
 5433 0          0:00 nc -l
 5648 0          0:07 telnetd -l /bin/sh -p 32769
/ # netstat -t
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 ::ffff:10.0.2.15:32769  ::ffff:10.0.2.2:2095    ESTABLISHED
/ # mkdir . .. / bin
mkdir: can't create directory '..': File exists
mkdir: can't create directory 'bin': File exists
/ # ls -laR
.:
total 0
/ #

Note well: per the Ubuntu link: do NOT try this on any distro other than mll!!!

Code:

/ # mkdir . .. / bin
mkdir: can't create directory '..': File exists
mkdir: can't create directory 'bin': File exists
/ # ls -laR /
.:
total 0
/ #

Is there any way to fix this (without rebooting)? ?? ???

pompous ninja · 12-17-2017, 12:47 PM

Quote:

Originally Posted by astrogeek

In my personal opinion, you shouldn't.

The examples given are not dangerous Linux commands, they are examples of short programs contrived for the purpose of causing harm to a Linux system. If you were to ask "How many ways can I break into a Linux system?", the discussion would not be allowed under LQ rules:

In my opinion, promoting a discusion of "How many ways can I harm a Linux system?", outside any otherwise useful context, should fall under that same rule and not be allowed.

On that basis I am reporting this thread to other moderators for comment and possible action.

Thank you, astroogeek!

Why the Ubuntu forums say that these commands are dangerous?

Reference: https://ubuntuforums.org/announcement.php?f=326

If these commands are dangerous or not, I want to be well informed to avoid "all dangerous Linux command".

If I am not answered here in Linux Questions, what should I study to know the answers?

astrogeek · 12-17-2017, 12:52 PM

Quote:

Originally Posted by pompous ninja

Why the Ubuntu forums say that these commands are dangerous?

You should ask in the Ubuntu forums, not LQ.

Quote:

Originally Posted by pompous ninja

I want to be well informed to avoid "all dangerous Linux command"... what should I study to know the answers?

You should study Linux/Unix/Computing general knowledge and best practices, that will cover all bases, known and not yet encountered.

You should ask yourself, "How can I promote useful, helpful discussion, beneficial to all?" and leave off from seeking out everything negative and harmful.

pompous ninja · 12-17-2017, 01:17 PM

Quote:

Originally Posted by astrogeek

In my personal opinion, you shouldn't.

The examples given are not dangerous Linux commands, they are examples of short programs contrived for the purpose of causing harm to a Linux system. If you were to ask "How many ways can I break into a Linux system?", the discussion would not be allowed under LQ rules:

In my opinion, promoting a discusion of "How many ways can I harm a Linux system?", outside any otherwise useful context, should fall under that same rule and not be allowed.

On that basis I am reporting this thread to other moderators for comment and possible action.

I posted this topic because I believed in Ubuntu Forums.

Ubuntu Forums says that these commands are dangerous: https://ubuntuforums.org/announcement.php?f=326

If these commands are not dangerous, I should not have posted this topic.

astrogeek and moderators, sorry me!

If is better to lock the topic, please lock!

ntubski · 12-17-2017, 01:22 PM

Quote:

Originally Posted by pompous ninja

I posted this topic because I believed in Ubuntu Forums.

Believing things written on the internet is dangerous though

pompous ninja · 12-17-2017, 01:31 PM

Quote:

Originally Posted by ntubski

Believing things written on the internet is dangerous though

Believe in things written on the academic books is also dangerous?

Believe in the academic teachers is also dangerous?

!!! · 12-17-2017, 01:50 PM

Yes; yes(1)

Quote:

/ # mkdir . .. / bin
mkdir: can't create directory '..': File exists
mkdir: can't create directory 'bin': File exists
/ # ls -laR /
.:
total 0
/ #

Is there any way to fix this (without rebooting my mll VBox)? ?? ???

(I'll loose everything if I reboot, because I have no .vdi)

I guess I must be on everyone's 'ignore list'

. I give up. Bye.

pompous ninja · 12-17-2017, 02:37 PM

Quote:

Originally Posted by !!!

Code:

/ # mkdir . .. / bin
mkdir: can't create directory '..': File exists
mkdir: can't create directory 'bin': File exists
/ # ls -laR /
.:
total 0
/ #

Is there any way to fix this (without rebooting)? ?? ???

@!!!

Why do not you ask this to Theo de Raadt and all official OpenBSD developers?

Why do not you put this question in OpenBSD misc mailing list?

Reference: (misc@openbsd.org): https://marc.info/?l=openbsd-misc

OpenBSD is the operating system most secure of world.

ntubski · 12-17-2017, 03:02 PM

Quote:

Originally Posted by pompous ninja

Believe in things written on the academic books is also dangerous?

Of course; you don't think people burn books just for fun, do you?

Quote:

Believe in the academic teachers is also dangerous?

Yup, that's why they executed Socrates.

ondoho · 12-18-2017, 12:43 AM

just a word of warning, the op is a classical troll.

this is not name-calling; i'm stating a fact. look up the definition in the above link.

it never gets abusive, that's the clever part, but apart from that: its threads have no meaning except pushing well-known buttons, relentlessly.
look at their backlog here on LQ; now it also opened an account "supreme ninja" over at debian forums and created a thread IDENTICAL to this one.

Trihexagonal · 12-18-2017, 01:21 AM

Quote:

Originally Posted by pompous ninja

...I want to avoid all the dangerous Linux commands!

Then stick with Windows, or have someone else Admin your *NIX machine for you and permit you access to a usr account only.

cynwulf · 12-18-2017, 03:11 AM

Quote:

Originally Posted by pompous ninja

an ignorant user may be fooled

Yes, this is the case. It doesn't just apply to Linux either. Logging into any *nix like system as root and running commands copied and pasted from the WWW has the potential to be destructive.

Similarly in Windows, running some random batch files as an admin level user, or just downloading and running malware 'infected' files has the potential to be destructive or compromise the system.

Listing "dangerous commands" won't change any of this.

onebuck · 12-18-2017, 06:09 AM

This thread is being closed for violation of the LQ Rules for potential dangerous action to LQ & members.

jeremy · 12-18-2017, 11:49 AM

pompous ninja,

You're forming a pattern here, and multiple consecutive threads of yours have now been closed. If you'd like to continue participating at LQ, please change this behavior.

--jeremy