Linux Administration

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How to Install SVN on Ubuntu


AWS Redhat RHEL Install LAMP

Install VPN PPTPD on RHEL 7

AWS Redhat RHEL Install Ruby and Rails

Ubuntu Install GUI

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 -)

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 16.4 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

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)\[\033[00m\] $ "