If you are getting the following error
“Couldn’t create temporary archive name.”
Check if you are out of disk space.
df -h
After freeing up some space, you should be able to continue increasing the disk size
lvextend -l +100%FREE /dev/redhat/root xfs_growfs /dev/redhat/root
These steps should be similar across Red Hat type distros.
Before we proceed, lets stop SNMP
sudo systemctl stop snmpd
First we are going to disable SNMP v1 and v2c
You can manually edit the /etc/snmp/snmpd.conf file and comment out or delete every line starting with com2sec, group, access. Or you can run the following sed commands to change it for you.
sudo sed -i 's/^com2sec/# com2sec/g' /etc/snmp/snmpd.conf
sudo sed -i 's/^group/# group/g' /etc/snmp/snmpd.conf
sudo sed -i 's/^access/# access/g' /etc/snmp/snmpd.conf
https://serverfault.com/questions/376688/how-to-disable-version-1-and-version-2c-in-snmpd
Follow the prompts to create a SNMP v3 user.
sudo net-snmp-create-v3-user -ro -a SHA -x AES
Start SNMP
sudo systemctl start snmpd
You should be good to go.
If you are running a firewall, you will need to allow an exception for SNMP, UDP port 161. You may also need to allow an SELinux exception. Check out the last portion of both these articles.
Bob has a computer running Fedora. When he installed Fedora he didn’t setup the root password and locked the root account. That is best practice. Right? Then one day he goes to upgrade to the latest version of Fedora and types in
sudo dnf update
and is greeted with
What happened? I had access before? Bob thinks to himself. Seems like I am not in the wheel group anymore. Bob being a smart person decides to attempt recovery mode. He’ll boot up and just readd his user to the wheel group.
Recovery mode starts up and then fails due to the root account being locked. What?!
Bob then starts talking to himself as he is in need of some expert advice. What other options do I have. I know! He runs to find his handy dandy Live Fedora pen drive. Plugs it in and boots up into a live version of Fedora. Now I can mount and access the main drive.
But wait, I can’t run “usermod -G wheel bob” because that will only affect the Live System. I could chroot into the drive. That would require mounting some extra mount points. Is there a faster way? We could maybe edit the /etc/group and add “wheel:x:10:bob”. That should add bob back to the wheel group. Right?
Wait, what about the sudoers file. We are normally supposed to use “sudo visudo” command to modify the file. Let’s check the file and see if we can just manually edit it.
$ stat -c "%n %a" /etc/sudoers /etc/sudoers 440 $
Hmm, okay I am going to need to change permissions to save the file. Let’s chmod that to 644 temporarily
$ sudo chmod 644 /etc/sudoers
Alright now I should be able to edit it.
$ sudo vi /etc/sudoers
Okay, now I need to explicitly give myself permission to use sudo. Where is that line. Ah-ha!
root ALL=(ALL) ALL
Lets duplicate that with yy and p, replace root with my username.
root ALL=(ALL) ALL bob ALL=(ALL) ALL
Save that with esc then :wq enter
Now change the file permissions back
sudo chmod 400 /etc/sudoers
Reboot the system and now lets login and test sudo.
$ sudo whoami root
Success!
Bob, satisfied that the problem is resolved, rewards himself by getting a sandwich.
sudo make me a sandwich
https://docs.fedoraproject.org/en-US/quick-docs/root-account-locked/
You sometimes need to set the coolbits value to overclock your GPU on Linux
You’ll need to install nvidia-xconfig
sudo dnf install nvidia-xconfig
Then you can set the cool bits value with the following command. Change 24 to the appropriate cool bits value. Refer to the link below.
sudo nvidia-xconfig --cool-bits=28
It’ll create a new xorg config file. Reboot to take advantage of cool bits being enabled.
Multiple GPUs
If you have multiple GPUs, you will need to do the following to enable cool bits on each GPU.
sudo nvidia-xconfig -a --cool-bits=28 --allow-empty-initial-configuration
https://wiki.archlinux.org/title/NVIDIA/Tips_and_tricks#Enabling_overclocking
List snapper BTRFS snapshots with
snapper list
If you are in recovery mode on Fedora, add –no-dbus right after the snapper command. e.g.
snapper --no-dbus list
You can use the diff command to list the changes that happened between snapshots.
snapper --no-dbus diff 108..109
And to undo a change or all the changes between a snapshot, do the following. Where 108..109 are all the changes you want to remove. So essentially going back to snapshot 108.
snapper --no-dbus -v undochange 108..109
https://documentation.suse.com/sles/11-SP4/html/SLES-all/cha-snapper.html
Installing KDE on Fedora is super simple. You can run the following command to install the whole KDE Plasma Workspace.
sudo dnf -y group install "KDE Plasma Workspaces"
Once installed, reboot and on the login screen select the Gear options and select Plasma
By default Linux and OLED displays don’t really want to play well together. icc-brightness is a handy utility that resolves the problem, but all the instructions I found online were for Ubuntu/Debian based distributions.
https://github.com/udifuchs/icc-brightness
Fortunately, after a few failed attempts to compile the program I was able to figure out which dependency was required.
[admin@local icc-brightness]$ sudo make
cc -W -Wall icc-brightness-gen.c -l lcms2 -o icc-brightness-gen
icc-brightness-gen.c:9:10: fatal error: lcms2.h: No such file or directory
9 | #include <lcms2.h>
| ^~~~~~~~~
compilation terminated.
make: *** [Makefile:10: icc-brightness-gen] Error 1
admin@local icc-brightness]$
We are missing the lcms2-devel package. Not sure if the utils package is required, but installed it anyway.
sudo dnf install lcms2-utils lcms2-devel
With that installed we can now make and install icc-brightness
sudo make install
Reboot the laptop and it should automatically start icc-brightness in the background and the brightness controls should work
You can find more information for installing on Debian based systems at the following link.
We are going to setup a Samba/CIFS share on Fedora Server that we will then access from Windows 10.
First we need to install the samba package.
sudo dnf install samba
Next, lets enable the Samba service so it automatically starts when the server boots up.
systemctl enable smb nmb systemctl start smb
nmb is a “NetBIOS name server that provides NetBIOS over IP naming service to clients”
https://www.samba.org/samba/docs/current/man-html/nmbd.8.html
We now need a user to connect to the Samba share with. You can use the commands below to to create a new user.
pdbedit only configures a current Linux system user for Samba. You can skip creating a new Linux user, but only if there is one already created that you can use.
sudo useradd -m sambaUser sudo passwd sambaUser sudo pdbedit -a sambaUser
Configure SELinux permissions with the following command.
sudo setsebool -P samba_enable_home_dirs on
You can also just disable SELinux. Although it is not necessarily recommended.
How To Enable/Disable SELinux
sudo setsebool -P samba_enable_home_dirs on sudo firewall-cmd --add-service=samba --permanent sudo firewall-cmd --reload
You can now test to see if the share works. Open up Windows Explorer. Type in the IP address of the server and connect.
\\ip-address\sambaUser
It should prompt you for a login. Enter the user and password you set up.
If it loads, then congratulations! You have successfully setup a Samba/CIFS Share on Fedora Server. Create new directories or files or whatever else you need.
Check out the following links for more information about setting up Samba.
https://fedoramagazine.org/fedora-32-simple-local-file-sharing-with-samba/
https://jewelhuq.wordpress.com/2017/12/08/how-to-install-samba-server-in-fedora/
https://fedoramagazine.org/fedora-32-simple-local-file-sharing-with-samba/
There are a few different ways to view RAID information on Fedora. Here are two commands that can help.
You can copy and past the following command to print the mdadm configuration.
cat /etc/mdadm.conf
It should return something similar to the following.
$ cat /etc/mdadm.conf # mdadm.conf written out by anacondaMAILADDR root AUTO +imsm +1.x -all ARRAY /dev/md/Boot level=raid0 num-devices=6 UUID=21ce258a:015d0dd4:90d5b80e:ab04b7f7 ARRAY /dev/md/Root level=raid0 num-devices=6 UUID=4be32ad0:f3aa77bd:139d749d:4a6aab60
We see from the above output that we have two raid arrays. Both RAID 0 over 6 drives.
You can show the mdstats by running
cat /proc/mdstat
Should get output similar to the following.
$ cat /proc/mdstat
Personalities : [raid0]
md126 : active raid0 sdc2[0] sdf2[5] sde2[4] sdd2[1] sda2[2] sdb2[3]
5856552960 blocks super 1.2 512k chunks
md127 : active raid0 sdc1[0] sdf1[5] sde1[4] sdd1[1] sdb1[3] sda1[2]
3133440 blocks super 1.2 512k chunks
unused devices:
This shows us the RAID size. About 5TB on one and 3GB on the other. The 3GB is used for the boot partition.
Apparently there is a difference between “mdadm” and “dm-raid”
Mdadm is for managing and creating software raids, while dm-raid interacts if a device like a laptop has a “fake RAID”
https://superuser.com/questions/721795/how-fake-raid-communicates-with-operating-systemlinux/721796#721796
https://stackoverflow.com/questions/23164384/what-is-the-difference-between-dm-and-md-in-linux-kernel
For more information on managing RAID with Mdadm, you can refer here.
CentOS/Fedora/RedHat
Add sudo privileges
usermod -a -G wheel LinuxUsername
remove
sudo deluser username wheel
Ubuntu/Debian
Add sudo privileges
usermod -a -G sudo LinuxUsername
remove
sudo deluser username sudo