Lunetikk's IT Wiki linux:general

linux:general:awk

Anonymous (anonymous@undisclosed.example.com) — 2019-10-11T15:01:08+00:00

AWK 30 Examples for Awk Command in Text Processing

linux:general:basics

Anonymous (anonymous@undisclosed.example.com) — 2022-12-16T10:41:44+00:00

Linux Commands Command Function cd {/folder/} cd (change directory), changes the current directory to folder pwd shows current directory ls shows all files and folders in the current directory in one line -> confusing) ll = ls –al

linux:general:crontab

Anonymous (anonymous@undisclosed.example.com) — 2019-10-07T10:59:36+00:00

Cron What is Cron/ Crontab/ Cronjob? Wikipedia - Cron How to edit a cron For global use, edit “/etc/cron.d/general” For a specific user, execute “crontab -e” with that user. ┌───────────── minute (0 - 59) │ ┌───────────── hour (0 - 23) │ │ ┌───────────── day of month (1 - 31) │ │ │ ┌───────────── month (1 - 12) │ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday; │ │ │ │ │ 7 is also Sunday) │ │ │ │ │ │ │ │ │ │ * * * * * command t…

linux:general:ffmpeg

Anonymous (anonymous@undisclosed.example.com) — 2023-04-29T21:16:57+00:00

FFmpeg "FFmpeg is a free software project consisting of a vast software suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the FFmpeg program itself, designed for command-line-based processing of video and audio files, and widely used for format transcoding, basic editing (trimming and concatenation), video scaling, video post-production effects, and standards compliance (SMPTE, ITU). FFmpeg includes libavcodec, an audio/video code…

linux:general:firefox

Anonymous (anonymous@undisclosed.example.com) — 2019-10-28T23:05:55+00:00

Firefox Installation apt-get install firefox Configuration You can set different Useragents (about:config) via configfile Change to the dir, the defaultname is different for everybody cd /home//.mozilla/firefox/*default/ The default config is located in

linux:general:git

Anonymous (anonymous@undisclosed.example.com) — 2017-12-19T17:12:10+00:00

Git Commands Command Function git log --follow check_symlink shows the change history of the file “check_symlink” git remote -v verify the remote url (origin) of the current repository git config --global user.email “

linux:general:iptables

Anonymous (anonymous@undisclosed.example.com) — 2022-02-09T15:26:23+00:00

IPTables Configure List rules iptables -L #or iptables -L -n Add rule #reject connections iptables -A -d /32 -j REJECT --reject-with icmp-port-unreachable Remove rule #list rules in chain iptables -L --line-numbers #remove line 1 in chain iptables -D 1

linux:general:lvm

Anonymous (anonymous@undisclosed.example.com) — 2020-11-16T17:39:12+00:00

Logical Volume Manager (LVM) What is LVM? Wikipedia - Logical Volume Manager Create new Physical Volume (PV), Volume Group (VG) and Logical Volume (LV) First you need to create a partition on a disk with type LVM List the partitions cat /proc/partitons major minor #blocks name 11 0 1048575 sr0 8 0 31457280 sda 8 1 194560 sda1 8 2 31260672 sda2 8 16 209715200 sdb

linux:general:mailq

Anonymous (anonymous@undisclosed.example.com) — 2018-05-28T14:39:41+00:00

Remove mails from mailqueue Postfix Remove mails service postfix stop postsuper -d ALL mailq service postfix start Sendmail Remove mails Remove some mails: service sendmail stop rm /var/spool/mqueue/* rm /var/spool/mqueue-client/* mailq service sendmail start

linux:general:md5

Anonymous (anonymous@undisclosed.example.com) — 2019-11-15T10:06:22+00:00

MD5 Get MD5 sums of files Execute the following script to get md5 sums of multiple files in dir /VMDKS/lunetikk/ #!/bin/bash SYSTEM=lunetikk touch /tmp/md5sums-$SYSTEM.txt for file in /VMDKS/$SYSTEM/* do md5sum $file >> /tmp/md5sums-$SYSTEM.txt done

linux:general:mkv

Anonymous (anonymous@undisclosed.example.com) — 2026-01-20T10:09:14+00:00

Edit .mkv To edit these files, install mkvtoolnix and ffmpeg Issues Videos are working in VLC but not on TV - rebuild the container (Repack) ffmpeg -i input.mkv -map 0 -c copy -fflags +genpts output_fixed.mkv

linux:general:mount

Anonymous (anonymous@undisclosed.example.com) — 2020-01-09T16:36:49+00:00

Mount networkshares Clientpackages to mount shares CIFS: apt-get install cifs-utils NFS: apt-get install nfs-common Temp. mount CIFS / SAMBA mount -t cifs //// /mnt// or with connection parameters mount -t cifs //// /mnt// -o username=user,password=pass,domain=dom

linux:general:mysql

Anonymous (anonymous@undisclosed.example.com) — 2020-01-13T22:31:04+00:00

MySQL Install apt-get install mysql-server Configure Execute the following after the installation mysql_secure_installation You can find the config in /etc/mysql/mysql.conf.d/mysqld.cnf Passwordless login If you want to automate things you might want to login without a plaintext password.

linux:general:network

Anonymous (anonymous@undisclosed.example.com) — 2022-12-16T10:51:33+00:00

Network Ports PortProtocol 20 + 21 FTP 22 SSH 25 SMTP 80 HTTP 111 + 2049 TCP/UDP - NFS 123 UDP - NTP 137 + 139 + 445 TCP/UDP - SMB/Samba 443 HTTPS 8080 Proxy 3389 RDP 3306 MySQL Configuration

linux:general:putty

Anonymous (anonymous@undisclosed.example.com) — 2019-12-10T17:11:43+00:00

PuTTY Download PuTTY This is the most common client http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html KiTTY This client is PuTTY with some extra features which are really helpful http://kitty.9bis.net/ Configuration SSH Key Download “puttygen” http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html - Select SSH-2 RSA - 2048 bit or higher - Click generate - Edit comment

linux:general:qol

Anonymous (anonymous@undisclosed.example.com) — 2023-01-22T18:20:06+00:00

Quality of life improvements VI Install VIM apt install vim Deactivate visual mode echo "set mouse-=a" >> ~/.vimrc Shell Use alias Use an alias to make long commands you need often short open /etc/.bashrc and add lines like the following

linux:general:resetroot

Anonymous (anonymous@undisclosed.example.com) — 2022-09-03T16:48:57+00:00

Reset Root Password Reboot your system and press “e” in GRUB Replace the second last line starting from “ro” to the following rw init=/bin/bash Then press “F10” to boot You should see a rootshell just like this Enter “passwd

linux:general:ssh

Anonymous (anonymous@undisclosed.example.com) — 2018-12-20T17:44:24+00:00

SSH Installation apt-get install openssh-server Configuration In “/etc/ssh/sshd_config” PermitRootLogin no RSAAuthentication yes PubkeyAuthentication yes PasswordAuthentication yes service ssh restart

linux:general:sslcert

Anonymous (anonymous@undisclosed.example.com) — 2018-12-07T21:35:11+00:00

SSL Certs Check the following sites: Certbot / LetsEncrypt tmade.de apache

linux:general:sudoers

Anonymous (anonymous@undisclosed.example.com) — 2022-08-31T10:19:02+00:00

Sudoers Configuration In “/etc/sudoers” #allow user "user1" to become root via "sudo su -" user1 ALL=(ALL) NOPASSWD: ALL #allow user "nagios" to execute the script "check_fail2ban" with root privileges nagios ALL=(ALL) NOPASSWD: /usr/lib/nagios/plugins/check_fail2ban

linux:general:swap

Anonymous (anonymous@undisclosed.example.com) — 2019-02-12T14:45:49+00:00

Swap What is Swap? Wikipedia - Paging Create a (temp.) swapfile and add it to swap Create a swapfile with blocksize 1024 and 2GB dd if=/dev/zero of=/swap/swapfile bs=1024 count=2M Format the file and set permissions mkswap /swap/swapfile chown root:root /swap/swapfile chmod 600 /swap/swapfile

linux:general:troubleshooting

Anonymous (anonymous@undisclosed.example.com) — 2020-12-03T15:12:27+00:00

Troubleshooting Removing old kernels leads to broken symlinks Description apt-get autoremove leads to a broken symlink which requires a reload of grub apt-get autoremove ... The link /vmlinuz.old is a damaged link Removing symbolic link vmlinuz.old you may need to re-run your boot loader[grub] The link /initrd.img.old is a damaged link Removing symbolic link initrd.img.old you may need to re-run your boot loader[grub]