Linux Administration

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How to Install SVN on Ubuntu


AWS Redhat RHEL Install LAMP

Install VPN PPTPD on RHEL 7

Install OPen VPN client on ubuntu

#setup /etc/openvpn/openvpn.conf

#manually start
sudo openvpn --config /etc/openvpn/openvpn.conf &

AWS Redhat RHEL Install Ruby and Rails

Ubuntu Install GUI

clean up linux disk space

sudo journalctl --vacuum-time=2d
sudo apt-get autoremove --purge

sudo snap set system refresh.retain=2

tar and gzip

Archive a set of files:

tar -cvf tarfile.tar /var/log/syslog /var/log/messages

Archive and compress (gzip) a set of files:

tar -cvzf file.tar.gz /var/log/syslog /var/log/messages

Archive and compress (bzip2) a set of files:

tar -cvjf file.tar.bz2 /var/log/syslog /var/log/messages

Extract a tar file:

tar -xvf file.tar
tar -xvzf file.tar.gz
tar -xvjf file.tar.bz2

Display the content of a tar file:

tar -tvf file.tar
tar -tvzf file.tar.gz
tar -tvjf file.tar.bz2

Replace a file in an existing tar file:

tar -rvf tarfile.tar filetoreplace

Update a file in an existing tar file:

tar -uvf tarfile.tar newfile

Copy all files in one directory to another directory on local host:

cd /etc; tar cf – . | (cd /etc.bak; tar xvpf -)

#parallel zip
# compress
pigz -2 ./abc.vdi
# extract / decompress
pigz -d ./abc.vdi.gz

zip with split and password


zip --encrypt -s 4g -r files


// recursive zip all folder
// with password
// split 4gb
zip --password password -s 4g -r input &
// with store only and 1gb split
zip -Z store -r -s 1g input/

no hangup even if logged out of ssh

nohup bash &> script.log &

DB backup

  1. mysqldump -u root -p [root_password] [tabdaase_name] > dumpfilename.sql
  2. mysqldump -u root -p password sugarcrm > sugarcrm.sql


  1. mysqldump -u root -ptmppassword --databases bugs sugarcrm > bugs_sugarcrm.sql

mysql -u root -p[root_password] [database_name] < dumpfilename.sql

Cron job backup mysql databse every week

# Back up db. Run once a week at midnight on Sunday morning
0 0 * * 0 mysqldump -u root -pPASSWORD DB_NAME | gzip > /tmp/wiki_database_`date +'%Y-%m-%d'`.sql.gz

Search specific text among files

grep -H "textToFind" /var/www/*
grep -H "textToFind" /var/www/sites/*/html/.htaccess

Search file

find /home/david -name 'index*'

SVN cheat sheet
Set up svn in Ubuntu

Apache Rewrite

CodeIgniter Rewrite Rules

<IfModule mod_rewrite.c>
	#Disable file listing
	Options -Indexes
    RewriteEngine On
    RewriteBase /
	#force www
	RewriteCond %{HTTP_HOST} ^hawkguide\.com [NC] 
	RewriteRule ^(.*)$1 [R=301,QSA,L] 
    #Removes access to the system folder by users.
    #Additionally this will allow you to create a System.php controller,
    #previously this would not have been possible.
    #'system' can be replaced if you have renamed your system folder.
    RewriteCond %{REQUEST_URI} ^system.*
    RewriteRule ^(.*)$ /index.php?/$1 [L]
    #When your application folder isn't in the system folder
    #This snippet prevents user access to the application folder
    #Submitted by: Fabdrol
    #Rename 'application' to your applications folder name.
    RewriteCond %{REQUEST_URI} ^application.*
    RewriteRule ^(.*)$ /index.php?/$1 [L]

    #Checks to see if the user is attempting to access a valid file,
    #such as an image or css document, if this isn't true it sends the
    #request to index.php
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php?/$1 [L]

Create User

adduser newuser

Add a existing user to a group usermod -a -G www-data jerry

ImageMagick merge images

montage f*.jpg -tile 1x22 -geometry 1576x930+0+0 tile_.jpg

listen ports

 netstat -a | egrep 'Proto|LISTEN'

Disable prompt when ssh to unknown host

echo -e "StrictHostKeyChecking no\n" >> ~/.ssh/config

Apache server log permission denied

In CentOS
Permission denied: [client xx:xx] AH00132: file permissions deny server access: /var/www/ Run

restorecon -R /var/www/foldername

squid 3.3 on centos

Configure SSL Bump on squid 3.3

List disk usage by directory

du -h <dir> | grep '[0-9\.]\+G'

Ubuntu create swap

sudo fallocate -l 1G /swapfile
ls -lh /swapfile
sudo chmod 600 /swapfile
ls -lh /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
sudo swapon --show

to auto mount

echo '/swapfile none swap sw,nofail 0 0' | sudo tee -a /etc/fstab

use entire disk for swap

sudo mkswap /dev/nvme4n1
sudo swapon /dev/nvme4n1

How to auto run scripts at system start in Cent OS 7

/etc/rc.local or /etc/rc.d/rc.local are no longer executed by default due to systemd-changes. to still use those, you need to make /etc/rc.d/rc.local executable:

chmod +x /etc/rc.d/rc.local
sudo vim /etc/rc.d/rc.local
# then add yout commands to run

Mac fix mongodb max file limit issue / Adjust ulimit

echo kern.maxfiles=65536 | sudo tee -a /etc/sysctl.conf
echo kern.maxfilesperproc=65536 | sudo tee -a /etc/sysctl.conf
sudo sysctl -w kern.maxfiles=65536
sudo sysctl -w kern.maxfilesperproc=65536

Then set ulimit in bash_profile

echo "ulimit -n 65536 65536" >> ~/.bash_profile

Ubuntu set timezone

sudo dpkg-reconfigure tzdata

Mac show git branch name in terminal

Add following code into ~/.bash_profile

parse_git_branch() {
  git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ (\1)/'

export PS1="\u@\h \W\[\033[32m\]\$(parse_git_branch)\[\033[00m\] $ "

Prepare extra ~/bin folder for shortcut commands

edit ~/.bash_profile add line

export PATH="~/bin/:$PATH"

Auto generate git commit message with one file name

touch ~/bin/autocommit && chmod +x ~/bin/autocommit && vim ~/bin/autocommit 


BRANCH_NAME=$(git symbolic-ref --short HEAD)
COMMIT_MSG=$(LANG=C git -c color.status=false status \
| sed -n -E -e '1,/Changes to be committed:/ d'\
            -e '1,1 d' \
            -e '/git reset/ d' \
            -e '/^Untracked files:/,$ d' \
            -e 's/^\s*//' \
            -e 's/      modified:   //' \
            -e '/./p')
git commit -m "[${BRANCH_NAME}] ${FIRST_FILE}"

usage: just type autocommit and it will generate a commit message containing the current branch name and first file changed

Auto commit and push

git config --global push.default current
echo "autocommit && git push" > ~/bin/autopush
chmod +x ~/bin/autopush

usage: just type autopush

Mount hard drive

#find uuid
sudo blkid
#mount hard drive
sudo mount /dev/sda1 /mnt/ssd1

# auto mount
sudo vim /etc/fstab
UUID=0c18cc09-0028-4cb1-97ef-6222fe477432   /mnt/ssd   ext3    defaults,nofail     0        2

Better method

UUID=$(sudo blkid /dev/${DRIVE} -sUUID -ovalue)
echo $UUID
echo "UUID=${UUID} /mnt/${FOLDER} xfs defaults,nofail 0 2" | sudo tee -a /etc/fstab
sudo mount --uuid $UUID /mnt/${FOLDER}

fix corrupt hard drive file system

sudo gdisk /dev/sdb

sudo e2fsck /dev/sdb1

using gparted for over 2tb

sudo apt-get install -y gparted xfsprogs


sudo parted /dev/${DRIVE}

mklabel gpt
mkpart primary 0G 100%

sudo mkfs.xfs /dev/${DRIVE}1
sudo mkdir -p /mnt/${FOLDER}
# mount hard drive
UUID=$(sudo blkid /dev/${DRIVE}1 -sUUID -ovalue)
echo $UUID
echo "UUID=${UUID} /mnt/${FOLDER} xfs defaults,nofail 0 2" | sudo tee -a /etc/fstab
sudo mount --uuid $UUID /mnt/${FOLDER}

Test disk write speed

sudo chown -R $USER:$USER ./
dd if=/dev/zero of=./test1.img bs=1G count=1 oflag=dsync && rm ./test1.img

using fio

sudo apt-get install fio

fio --filename=test --sync=1 --rw=randread --bs=4k --numjobs=1 \
  --iodepth=4 --group_reporting --name=test --filesize=2G --runtime=300 && rm test

fio --filename=test --sync=1 --rw=randwrite --bs=4k --numjobs=1 \
  --iodepth=4 --group_reporting --name=test --filesize=2G --runtime=300 && rm test

Splunk installation

download splunk then follow

Change port

sudo vim $SPLUNK_HOME/etc/system/local/web.conf


httpport = 8866

Configure to start on boot time

sudo $SPLUNK_HOME/bin/splunk enable boot-start
sudo service splunk start

List file sizes by directory (depth = 1)

du -ah --max-depth=1 | sort -n

Copy files argument list too long

echo ./* | xargs cp -r --  /target-dir

echo ./* | xargs rsync -avh -- /target-dir

echo ./* | xargs  mv -t /target-dir --

clean up journal

sudo journalctl --vacuum-time=2days
sudo journalctl --vacuum-size=100M

sudo vim /etc/systemd/journald.conf
# change 
# SystemMaxUse=200M

sudo systemctl daemon-reload

Allow pm2 run via ssh and cron

n=$(which node); \
n=${n%/bin/node}; \
chmod -R 755 $n/bin/*; \
sudo cp -r $n/{bin,lib,share} /usr/local

method 2:

sudo rm -f /usr/local/bin/pm2 && sudo ln -s $(which pm2) /usr/local/bin/pm2

control cpu fan speed


sudo apt-get install fancontrol lm-sensors
sudo sensors-detect
# answer yes to all questions

check temp


edit /etc/default/grub to add acpi_enforce_resources=lax to the GRUB_CMDLINE_LINUX_DEFAULT

then run
sudo update-grub
sudo service kmod start
sudo pwmconfig

view current config


finally start fan control

sudo service fancontrol start

auto start

sudo update-rc.d fancontrol enable

config explaination

MINTEMP: The temperature (°C) at which to SHUT OFF the CPU fan. Efficient CPUs often will not need a fan while idling. Be sure to set this to a temperature that you know is safe. Setting this to 0 is not recommended and may ruin your hardware!

MAXTEMP: The temperature (°C) at which to spin the fan at its MAXIMUM speed. This should be probably be set to perhaps 10 or 20 degrees (°C) below your CPU's critical/shutdown temperature. Setting it closer to MINTEMP will result in higher fan speeds overall.

MINSTOP: The PWM value at which your fan stops spinning. Each fan is a little different. Power tweakers can echo different values (between 0 and 255) to /sys/class/hwmon/hwmon0/device/pwm1 and then watch the CPU fan. When the CPU fan stops, use this value.

MINSTART: The PWM value at which your fan starts to spin again. This is often a higher value than MINSTOP as more voltage is required to overcome inertia.

raw disk backup

if: input file

of: output file (image)

dd if=/dev/mmcblk0 of=/media/usb500/pi_system_torrent.image

search for file name or extension

search for file name or extension find . -iname "*.jpg"

delete files by matches

find . -iname "*.jpg" -delete

rsync file from remote to local

nohup rsync -avh -e "ssh -x -T -o Compression=no"* ./ >~/rsync.log &

The above command turn off compression so it will be faster.

rsync locally

sudo rsync -aqxP /mnt/ssd1/docker/ /nvmex4/docker


grep --color -n -C 1 "search_text" lib/npm.js


grep --color -n -e "search_text[abc|abe]" lib/npm.js

search all files recursive

grep -HR --color "loan" ./

backup whole system

sudo su
dd if=/dev/sdc | bzip2 > /mnt/ssdbackup/ubuntuBackUp201803.bz2
bzcat /mnt/ssdbackup/ubuntuBackUp201803.bz2 | dd of=/dev/sdc

Grow linux partitions on live system

Start socks proxy server

see use docker-compose

Install fusion io drive2 driver in ubuntu

fusionio driver

Port Forwarding Simple TCP Traffic

use rinetd

rinetd simple tcp traffic forwarding

This is useful for forwarding traffic to server behind vpn

Auto restart process if exit

echo $RIGID
STATUS=`ps -A | grep gethbsc`
# change channel to slack webhook
if [ ! -z "$STATUS" -a "$STATUS" != " " ] ; then
  echo $STATUS
  echo "Restart service"
  cd ~/bsc && bash ~/bsc/
  curl -X POST -H 'Content-type: application/json' --data "{\"text\":\"server=${RIGID} node down\"}" $CHANNEL

RDMA NDS system via infiniband

this only works in centOS8

on server

change nfs disk array server ib ip to

change client server ib ip to

vim /etc/exports
# edit and add

sudo exportfs -a
sudo modprobe xprtrdma
sudo modprobe ib_ipoib
echo "rdma 20049" | sudo tee -a /proc/fs/nfsd/portlist

on client

sudo modprobe xprtrdma
sudo modprobe ib_ipoib
sudo mount -o rdma,port=20049 /mnt/nfs

LVM disk merged drive

follow instructions at

sudo apt-get -y install lvm2
sudo lvmdiskscan
sudo pvcreate /dev/${DRIVE}
sudo vgcreate nvmeg /dev/nvme2n1 /dev/nvme3n1 /dev/nvme4n1 /dev/nvme5n1 /dev/nvme0n1 /dev/nvme1n1
sudo vgextend nvme4 /dev/${DRIVE}
# create logical volume to take 100% space
sudo lvcreate -l 100%FREE -n main nvmeg
sudo fdisk -l
# Disk /dev/mapper/nvmeg-main: 9.1 TiB, 10001997365248 bytes, 19535151104 sectors
sudo lvmdiskscan
sudo fdisk -l
# extend volume and grow
sudo lvextend -l +100%FREE /dev/mapper/nvme4-nvme4t
sudo xfs_growfs -d /mnt/nvme1

setup frp

Setup FRP

setup apache reverse proxy

Setup apache2 reverse proxy



Github Action Runner

Github Action Runner

Squid https proxy

Squid proxy docker


enable oled and fan

systemctl enable --now kvmd-oled
systemctl enable --now kvmd-fan
# set admin login password
kvmd-htpasswd set admin


update routing table on boot

echo "route del default wlp2s0" > /path/to/

sudo vim /etc/systemd/system/myrouting.service




sudo systemctl enable myrouting.service

set iterm2 terminal proxy

export http_proxy=socks5://
export https_proxy=socks5://

dell open manage OSMA install

sudo apt install vim net-tools -y
# choose one
echo 'deb bionic main' | sudo tee -a /etc/apt/sources.list.d/
echo 'deb focal main' | sudo tee -a /etc/apt/sources.list.d/
echo 'deb jammy main' | sudo tee -a /etc/apt/sources.list.d/

sudo apt-key add 0x1285491434D8786F.asc
sudo apt-get update
sudo apt-get install srvadmin-all -y

echo -e "\n${USER}     *     Administrator" | sudo tee -a /opt/dell/srvadmin/etc/omarolemap
sudo service dsm_om_connsvc restart
sudo systemctl start dsm_sa_datamgrd && sudo systemctl start dsm_sa_eventmgrd

upgrade linux kernel to low latency

sudo apt install linux-lowlatency

sudo grep menuentry /boot/grub/grub.cfg

sudo vim /etc/default/grub
# change to 

sudo update-grub
sudo reboot

vnc server

vnc server

install openssl 3 on ubuntu

sudo apt-get install make cmake

tar -xzvf openssl-3.0.10.tar.gz
cd /openssl-3.0.10
sudo make install
sudo ldconfig

install cuda 11.7 with pytorch ubuntu 22

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt update
sudo apt-get remove --purge nvidia*
sudo apt-get autoremove

sudo apt-get install nvidia-driver-535

sudo apt-key adv --fetch-keys
sudo bash -c 'echo "deb /" > /etc/apt/sources.list.d/cuda.list'

sudo apt update

sudo apt-cache search cuda*
sudo apt install cuda-11-8

pip3 install torch torchvision torchaudio --index-url

# test pytorch cuda
import torch