> For the complete documentation index, see [llms.txt](https://lib.rjo.me/newlib/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://lib.rjo.me/newlib/operating-systems/linux.md). # Linux ## Finding out which Linux Version running ```sh cat /etc/issues cat /etc/os-release hostnamectl cat /etc/upstream-release/lsb-release ``` * `/etc/issues`: Linux Mint 21.1 Vera \n \l * `/etc/os-release`: more mint details * `/etc/upstream-release/lsb-release`: Ubuntu info * `lsb-release`: Here I will collect my general Tips on Linux\` ## Directories and permissions place additional package managers and executables in and config files. ```bash ~/.local/ ~/.config/ ``` Pretty Printing Path with each entry in new line as alias `ep` ```bash alias ep='echo $PATH | tr ":" "\n"' ``` ## Generate Random strings thanks to [How-to-Geek](https://www.howtogeek.com/howto/30184/10-ways-to-generate-a-random-password-from-the-command-line/) Generating 20 character long random strings. ```bash openssl rand -base64 20 ``` or ```sh < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c20 ``` On Mac prepend it with `LC_CTYPE=C`, like ```bash < /dev/urandom | LC_CTYPE=C tr -dc _A-Z-a-z-0-9 | head -c24 ``` ## Setup ssh Key connectivity Install openssh\_server ```sh sudo apt install openssh-server sudo systemctl is-enabled ssh ``` Generate a new ssh key pair ```sh ssh-keygen -t rsa -b 2048 -C "comments etc" -f ~/.ssh/outfile -N "" ssh-add ~/outfile ``` preferably store it in `/home//.ssh/` and append it into the `authorized_keys` File. Use the `-N ""` to avoid being prompted for a passphrase if desired. ```sh cat ~/.ssh/.pub >> ~/.ssh/authorized_keys ``` Update the sshd configuration to allow key based authorization. My preffered configuration checks the users .ssh directory for and `authorized_keys` File and also checks for a file per user like `/etc/ssh/authorized_keys/` Depending on the Firewall settings I sometimes have to run the openssh-server on a different port than 22 ```sh Port PubkeyAuthentication yes PasswordAuthentication no AuthorizedKeysFile %h/.ssh/authorized_keys /etc/ssh/authorized_keys/%u ``` Lastly copy the **private** `keyname` file to the machine you want to use to connect from. **The private keyfile is the key to access your host use caution and encryption when to save or share it.** ```sh scp ~/.ssh/keyname user@host:~/.ssh/ ``` ## Setting up Debian I used the debian-9.8.0-amd64-netinst.iso image. First I highlighted the *Install* option to avoid using the graphical installer. This is because I had issues in an earlier install when I was monitoring the log output and then switching back to the first console. Then I hit tab to add and additional boot parameter *netcfg/disable\_autoconfig=true*. This was because when I used automated Network Configuration, it defaulted to IPv6 and then froze when it tried to copy the apt mirrors because it didn't fell back to IPv4. I also used the following Partioning Table setup. ![Partioning Table](https://media.404founders.com/Partioning.jpg) To see the log output press `Ctrl+Alt+4` to switch back press `1` instead or use `2`or`3` to start a console terminal\ See also\ [Debian-Installer 5.1.7. The Boot Screen](https://www.debian.org/releases/stable/amd64/ch05s01.html.en#boot-screen)\ [Debian-Installer 5.3.2. Debian Installer Parameters](https://www.debian.org/releases/stable/amd64/ch05s03.html.en#ftn.idm1345)\ [Debian-Installer 6.1. How the Installer Works](https://www.debian.org/releases/stable/amd64/ch06s01.html.en) ## LVM LVM stands for **Logical Volume Management** and is used to create, display and manage **Physical Volumes(pv)**, **Volume Groups (vg)**, and **Logical Volumes (lv)** ## Installing Xen As described in [Xen Getting started](https://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide) ```sh apt-get install xen-system-amd64 lvm2 pvcreate /dev/sda7 vgcreate vg0 /dev/sda7 ``` `/dev/sda7` differs from the turorial due to my different partion tables I re-installed Linux-Mint on a setup with existing LVM settings. I mounted a data volume in `/etc/fstab` with `lvdisplay` revealed the `$` **LV Path** as `/dev/vg-01/data01` ```sh /dev/vg-01/data01 /data ext4 defaults 0 0 :/volume1/ /mnt/ nfs _netdev,nofail,x-systemd.automount,x-systemd.idle-timeout=600,timeo=50,retrans=2 0 0 ``` see `man mount` for more settings | option | description | | -------------------------- | ----------- | | \_netdev | | | nofail | | | x-systemd.idle-timeout=600 | | | timeo=50 | | | retrans=2 | | ## NFS Issues Make sure the `/etc/exports` file on the nfs server has the right ip addresses. They did not get updated when the ip address of the server changed due to a change of my ISP. The shared folder on the NasDrive needs to have nfs Permissions: | Setting | Value | | ----------------------- | ---------------------- | | - Client: | 10.0.0.\* | | + Privilege: | Read/Write | | \* Squash: | Map all users to admin | | \* Asynchronous: | No | | \* Non-privileged port: | Denied | | \* Cross-mount: | Allowed | Install **nfs-common** to mount nfs ```sh sudo apt-get install nfs-common ``` In `/etc/fstab` mount it with, make sure to ues **tabs** for separation (no spaces!) ```sh 192.168.1.152:/volume1/pullovas /home/wolle/nasghoul nfs defaults 0 0 ``` ## Mount Usb stick Find device location with `fdisk` and look for the flash drive, use the `exfat-fuse` if the stick is *exfat* formatted. To find out about the filsystem run `blkid`, then make the mount point and mount the drive. ```sh sudo fdisk -l sudo apt install exfat-fuse sudo blkid sudo mkdir /media//usbreb sudo mount /dev/sdc1 /media//usbreb -o uid=1000 ``` ## rsync Copying folders recursively with rsync\ `rsync --recursive --progress -v source/path destination/path` ## Mountpoint android phone The phone is mounted to the Computer through `mtp` and the SD-Card is in the phone\ `ls -lah /var/run/user/1000/gvfs/mtp:host=%5Busb%3A002%2C003%5D/SD\ card` ## Change screen brightness Install xbacklight and set screen brightness to 60% ``` sudo apt-get install xbacklight xbacklight -get display 60 ``` ## Install deb package run `sudo dpkg -i .deb` ### Check installed Ubuntu Version For Linux Mint ```bash optiplex in Library on  master [$!] ➜ cat /etc/upstream-release/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=22.04 DISTRIB_CODENAME=jammy DISTRIB_DESCRIPTION="Ubuntu Jammy Jellyfish" optiplex in Library on  master [$!] ➜ cat /usr/lib/os-release NAME="Linux Mint" VERSION="21.1 (Vera)" ID=linuxmint ID_LIKE="ubuntu debian" PRETTY_NAME="Linux Mint 21.1" VERSION_ID="21.1" HOME_URL="https://www.linuxmint.com/" SUPPORT_URL="https://forums.linuxmint.com/" BUG_REPORT_URL="http://linuxmint-troubleshooting-guide.readthedocs.io/en/latest/" PRIVACY_POLICY_URL="https://www.linuxmint.com/" VERSION_CODENAME=vera UBUNTU_CODENAME=jammy ``` ## Printing from the commandline ``` ~/Documents pyenv 🐍 system ➜ lpstat -p -d printer HP_LaserJet_M15w_0725E9_ is idle. enabled since Sun 22 Dec 2019 09:37:15 AM EST printer HP_LaserJet_M15w_0725E9_@NPI0725E9.local is idle. enabled since Sun 22 Dec 2019 09:39:27 AM EST no system default destination ~/Documents pyenv 🐍 system ➜ lpoptions -d HP_LaserJet_M15w_0725E9_ device-uri=ipps://HP%20LaserJet%20M15w%20(0725E9)._ipps._tcp.local/ printer-info='HP LaserJet M15w (0725E9)' printer-location printer-make-and-model='HP HP LaserJet M14-M17' printer-type=16781316 ~/Documents pyenv 🐍 system ➜ lp D\&B-E-card.pdf request id is HP_LaserJet_M15w_0725E9_-2 (1 file(s)) ~/Documents pyenv 🐍 system ➜ ``` ## Firewall Use `ufw` to allow firewall request for port and protocol. ``` sudo ufw allow 53 sudo ufw allow 53/tcp sudo ufw allow 53/udp ``` ## Pseudo stresstest forkbomb ```bash t(){for ((i=1; i<=100; i++ )) { (curl www.URL.com > /dev/null ; echo $i );next} & ; t } ``` Only blows your system without putting real stress on a server, but might get you banned or blocked.