RedHat 124 course

[UtwigMU]

I'm taking a RedHat 124 course (introductory) this week, where you learn stuff like Nautilus, Gnome, getting help, adding printers, basic bash commands, partitioning... The point is I'm supposed to teach it next month.

Even if I and most others on the course know the basics i learned a few neat thing about bash like:

CTRL+R to search history,
history, !932 (executes command with ID 932 in history)
bg, fg

If you start gui program from bash, you can suspend it with CTRL-Z and then tell it to go in background with bg and regain shell.

[Haig]

2 that I use quite often are:

- To monitor a file in realtime
tail -f


- Run a search query, save it to a txt file and email it to you

\o path to a text file
run a db query
\q
mutt -s "name" your email -a /path to file

[TransformX]

More cool stuff to know:

nohup: runs a process detached, so when you kill your terminal, the process lives
nc: VERY useful for checking connections, it's what you need right after ping.

!$ - the argument you used in the last command (mkdir Foo and then cd !$)

[UtwigMU]

LOL, he's teaching us how to do permissions and archives in Gnome (I prefer KDE and I hate Nautilus, when I played with SuSE I always made sure to yank Gnometastic file manager out of Firefox) and everyone at the course is typing in terminals. 124 is supposed to be entry level introductory course for noobs but only people who have experience and want certifications took it.

The thing I learned today: sticky permissions.

chmod +s

[dZeus]

some nice advice in this thread! Good that people use terminal/cli. GUI has no place on a server imo. In most cases it's a waste of RAM that could have been used for disk caching purposes.

Sticky permissions can be extremely usefull; especially when you've got writable samba shares.

Here's another trick:

if you can't unmount a filesystem because it's 'in use' by some program, check which programs are accessing it:

lsof /path

where /path is the start of the directory tree under which you want to see programs' access

If you want to see what a single program is using:

lsof -p `pidof program_name`

where program_name is the name of the executable (as listed in ps aux). Note the quotes, as they are forward quotes (under the thilde on a US keyboard) not regular single quotes. You can also directly type the pid of the program if you know it (ps aux again).

[UtwigMU]

Will have to take RHCSA exam on friday and I'm a bit scared.

Exam looks basically like this: You are given a live RedHat virtual machine and you're supposed first to take control over it by pausing and editing kernel parameters in grub and booting in single user mode, disable SELINUX enforcement and change root password.

Then you are given tasks such as create partition of size 200MB, formated in ext4 and mount it somewhere. You need to repartition and dabble with logical volumes in order to acomplish this. You may also create users, groups and directories with given permissions. You are allowed to use man pages and Gnome documentation. You can also install and use graphical tools but not internet.

At the end there are grading scripts similar to the course exercises and if you achieved requirements you have passed.

If you fail to gain root access to machine and don't get to exercise part you failed.

[dZeus]

how did the exam go?

[Marshmallowman]

thats what I like linux/unix, don't fix whats not broken I have flash backs from doing uni courses 20 years go with those nice(nice is good command too) commands I have forgoten... thanks for the refresher, pity you guys did not post them a few months ago, would have saved me a few days configuring an instrument logging box

[UtwigMU]

Shifted to next week. I was fixing stuff at other customers and I need to finalize tax report.

[UtwigMU]

Exam in nighbour country the morning, I need to drive there (1.5h) before that. Also yesterday and before yesterday I spent fixing customer's server which dropped, so I lost some precious last days studying time.

5 people, who are to file financial reports in 3 days or face paying penalty, watching you as you perform backup restore, knowing you are to commit harakiri on the spot if the restore doesn't work, does drain your energy.

[UtwigMU]

Exam is hard.

You are given a redhat desktop with virtual machine (both have Gnome).

First you need to take ownership of root account on the virtual machine and set network settings. Then you are presented with 17 tasks (stuff from RedHat 124 and 134 courses) you need to perform on virtual machine. Also you have a repository (which you need to configure), so you can install any graphical tool you may need if you have problems accomplishing something with CLI.

An example task would be configure a web server and download html file and put it in the document dir of the web server. You can accomplish this however you like.

You have 2.5 hours which gives you about 8 minutes per task and while you can search man pages, and online help pages in Gnome, there is not enough time to do so for every task.

You need to be well versed and be able to perform all tasks by mainly knowing what you need to do beforehand.

I was a bit underestimating it, since I expected less tasks and instructor on the course said you can find everything you need in the man pages, so I ran out of time for some tasks I could do.

[UtwigMU]

Epic fail, I'll be more prepared next time.

[dZeus]

it sounds like quite the lists of tasks for the allotted time. How are you supposed to acquire root? Do you edit the /etc/shadow file on the system partition to set root to a hash value of a known password? or are there specific tools in the hypervisor OS to gain root in virtual machine clients?

[UtwigMU]

Virtual machine is in gnome login screen, you shut it down, then you press e in grup, then add

single

to the end of first line.

After machine boots in single user mode you disable selinux by

setenforce 0

and do

passwd

.

At the end of exam the root password should be the password you are given in instructions.

You need to set root password, configure IP, mask, gateway and hostname before you can proceed to tasks.

[Marshmallowman]

I take it they don't secure single user mode, that would be a more interesting test