sfloess/Linux.md

## Linux.md

      
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              Linux.md
            
          
    Linux

Helpful tips and tricks for Linux.
How-To

Quickies


NetworkManager

Setup bridge

nmcli connection add type bridge autoconnect yes con-name [bridge name] ifname [bridge interface name]
nmcli con add type bridge-slave ifname [ethernet name] master [bridge hame]
Example

nmcli connection add type bridge autoconnect yes con-name bridge ifname bridge
nmcli con add type bridge-slave ifname enp34s0u2u1u2 master bridge


gvim doesn't resize:

edit ~/.bashrc
export GVIM_ENABLE_WAYLAND=true


Change MAC Address:  macchange -r [interface].  For example:  macchange -r wlp3s0
Display max supported RAM:  dmidecode --type 16
Check RAM speed:  dmidecode --type 17
List open ports and proceses that own them:

lsof -i
netstat -lptu
netstat -tulpn


Don't use a dnsmasq lease file:  --leasefile-ro
NIS:  domainname:  /etc/defaultdomain
Ensure laptop doesn't sleep/hibernate when lid is closed:  systemctl mask suspend.target
When booting headless, ensure console goes blank:  /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT="... consoleblank=[seconds to blank]"

Example: GRUB_CMDLINE_LINUX_DEFAULT="quiet consoleblank=20"
Make sure once edited, you run the following to ensure it "sticks" after next boot:

Debian:  update-grub
Fedora:  grub2-mkconfig -o /boot/grub2/grub.cfg


ISO

Mount:  mount -o loop [full path to ISO]/[ISO file name].iso [full path to mount point].  Example:  mount -o loop /path/to/disk1.iso /mnt/disk
Write an ISO to a USB stick:  dd if=[ISO file] of=/dev/[usb].  For example:  dd if=red_ribbon_lxde_14.03.iso of=/dev/sdb
Create from CD-ROM/DVD:  sudo dd if=/dev/cdrom of=/tmp/cdimg1.iso


mkv to mp4:  ffmpeg -i [mkv file].mkv -codec copy [new name].mp4
webm to mp4:  ffmpeg =i [webm file].webm -max_muxing_queue_size 200000 [new name].mp4

_Not sure about the 200000 - it's just what I am using


Disable notification-daemon/notify-send
Screen

Move to new position:  ctrl-a [: number X].  Example:  ctrl-a :number 3
Session in a session:  ctrl-a-a
Scroll with Mouse:  ~/.screenrc:  termcapinfo xterm* ti@:te@


Generate ssh host keys:  /usr/bin/ssh-keygen -A
BASH

printf:  %s, %b, %d, %x and %f


Alternatives

editor:  update-alternatives --config editor

Fedora:  export EDITOR=[path to editor]/[editor]  Example:  export EDITOR=/usr/bin/vim


java:  update-alternatives --config java
javac:  update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/open-jdk-11/bin/javac 1


Remove journaling ext4:  tune2fs -O ^has_journal /dev/[drive].  Example:  tune2fs -O ^has_journal /dev/sda1 
Emojis

Install
Latest Versions
Manal Installation

wget https://github.com/eosrei/emojione-color-font/releases/download/v1.4/EmojiOneColor-SVGinOT-Linux-1.4.tar.gz
tar zxf EmojiOneColor-SVGinOT-Linux-1.4.tar.gz
cd EmojiOneColor-SVGinOT-Linux-1.4
./install.sh
apt-get install ttf-bitstream-vera


Find default gateway:  ip route show

Look at the default line.
Example:

default via 24.211.184.1 dev brwan 
24.211.184.0/21 dev brwan proto kernel scope link src 24.211.184.21 
192.168.168.0/24 dev br0 proto kernel scope link src 192.168.16


Add Swap Space

Directions can be found here.

dd if=/dev/zero of=[swap file] bs=1MiB count=$(([number of GB]*2014))
sudo chmod 600 [swap file]
mkswap [swap file]
swapon [swap file]

Example


dd if=/dev/zero of=swapfile bs=1MiB count=$((2*2014))
sudo chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile

Cron

When run, to have emails sent to an address, add to /etc/crondtab:
MAILTO=[user]@[domain]
For example:  MAILTO=sfloess@mail
The basic structure can also be added to any individual user's crontab entries in the user's crontab file.
Include Git Repo in Your Prompt

.bashrc:
__compute_git_info() {
    local GIT_INFO="`git remote 2> /dev/null | tr -s '\n' '/' | rev | cut -c2- | rev` `git branch 2> /dev/null | grep -e '\* ' | sed 's/^..\(.*\)/\1/'`"

    if [ "${GIT_INFO}" != "/" ]
    then
        echo " ${GIT_INFO}"
    fi
}

__prompt_command() {
    local GIT_INFO=`__compute_git_info`

    PS1="[${GIT_INFO}] \`pwd\`> "
}

export PROMPT_COMMAND=__prompt_command
TLP

Adjusts power settings (here is a link for installing).  For max performance, here are a few notable settings:
TLP_ENABLE=1
TLP_DEFAULT_MODE=AC
DISK_IDLE_SECS_ON_AC=0
CPU_SCALING_GOVERNOR_ON_AC=performance
CPU_HWP_ON_AC=performance
CPU_MIN_PERF_ON_AC=100
CPU_MAX_PERF_ON_AC=100
CPU_BOOST_ON_AC=1
SCHED_POWERSAVE_ON_AC=0
ENERGY_PERF_POLICY_ON_AC=performance
SATA_LINKPWR_ON_AC="max_performance max_performance"

Additionally, there are two settings for CPU scaling that'll be dependent upon your CPU:  CPU_SCALING_MIN_FREQ_ON_AC and CPU_SCALING_MAX_FREQ_ON_AC
To list your CPU settings invoke the following:  tlp-stat -p
As an example, one of my servers lists the aforementioned as:   /sys/devices/system/cpu/cpu1/cpufreq/scaling_available_frequencies = 3000000 2667000 2333000 2000000 [kHz]
For this machine, I have these settings:
CPU_SCALING_MIN_FREQ_ON_AC=3000000
CPU_SCALING_MAX_FREQ_ON_AC=3000000

Apps


nexus.service

[Unit]
Description=Nexus Service
After=network.target

[Service]
Type=forking
WorkingDirectory=/opt/nexus/bin
ExecStart=/opt/nexus/bin/nexus start
ExecStop=/opt/nexus/bin/nexus stop
Restart=on-abort
TimeoutStartSec=600
TimeoutStopSec=600
RestartSec=600

[Install]
WantedBy=multi-user.target


activemq.service

[Unit]
Description=ActiveMQ Service
After=network.target

[Service]
Type=forking
PIDFile=/opt/apache-activemq/data/activemq.pid
WorkingDirectory=/opt/apache-activemq/bin
ExecStart=/opt/apache-activemq/bin/activemq start
ExecStop=/opt/apache-activemq/bin/activemq stop
Restart=on-abort
TimeoutStartSec=600
TimeoutStopSec=600
RestartSec=600

[Install]
WantedBy=multi-user.target
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