## getting started
git init
git add index.html
git commit -m"my first commit"
git diff
git clone public_html my_website

# git log
git status
git log
git show xxx
git diff xxx

## branching out
git branch
gi branch dev
git show-branch --more=5
git checkout dev
git checkout HEAD index.html
git merge dev
git diff
git reset --mixed HEAD^
git reset --hard ORIG_HEAD
git branch -d dev

## add shortcuts
git config --global alias.show-graph 'log --graph --abbrev-commit --pretty=online'

## plumbing commands
git ls-files --stage
git ls-files --unmerged
git cat-file -p xxx
git reflog

While the output of the top command displayed, press F, which will display all fields available for sorting, press n (which is for sorting the processes by Memory) and press enter.

press c, which will display full pathname of running processes

press 1 (number one), which will display the performance data of the individual CPUs.

You can get information about the make, model and serial number of the equipment as shown below:
# dmidecode -t system

What is the maximum RAM supported by the system?
# dmidecode -t 16

Currently installed RAM
# cat /proc/meminfo | grep -i memtotal

Memory slots occupied
# /usr/sbin/dmidecode -t 17 | grep -i size

// know more about running processes
# dstat

Consider setting up a simple Git alias for common but complex Git command that you type frequently.

git config --global alias.show-graph 'log --graph --abbrev-commit --pretty=oneline'

Add the following to the .gitconfig file in your $HOME directory.

[alias]
co = checkout
ci = commit
st = status
br = branch
hist = log --pretty=format:\"%h %ad | %s%d [%an]\" --graph --date=short
type = cat-file -t
dump = cat-file -p

Here is a quick way to send files from any server where mutt is installed.

echo "Attaching a file " | mutt -s "file attachment" -a /root/somefile.txt -- your.name@gmail.com

A few packages are dependent upon the server time. If the date is incorretly set, it will throw an exception as shown below.

# s3cmd ls
ERROR: S3 error: 403 (RequestTimeTooSkewed): The difference between the request time and the current time is too large.

/sbin/ntpdate ntp.ubuntu.com

Afer updating the date using ntpdate command, the s3cmd command started working as expected.

# date command can also be used
date +%Y%m%d -s "20130514"

We can use logger command in a crontab.

59 23 * * * /home/john/bin/backup.sh > /home/john/logs/backup.log | logger -t backup 2>&1

It is also possible to skip the standard error and let mailto send you the errors:

MAILTO=me@domain.com

Set up git:

yum install git-core
cd ~/.ssh
ssh-keygen -t rsa -C "shantanu.oak@gmail.com"

Contents of the file "id_rsa.pub" should be copied to gitHub site.
On the GitHub site Click “Account Settings” > Click “SSH Public Keys” > Click “Add another public key”

This will allow passwordless access to github site:
ssh -T git@github.com
_____

Global setup:

git config --global user.name "Shantanu Oak"
git config --global user.email shantanu.oak@gmail.com
_____

Next steps:

mkdir syllabalize_unicode
cd syllabalize_unicode
git init
touch README
git add README
git commit -m 'first commit'
git remote add origin git@github.com:shantanuo/syllabalize_unicode.git
git push -u origin master
_____

Existing Git Repo?

cd existing_git_repo
git remote add origin git@github.com:shantanuo/syllabalize_unicode.git
git push -u origin master
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clone (download) the source
git clone git@github.com:ahiguti/HandlerSocket-Plugin-for-MySQL.git
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Install MySQL

mkdir download
cd download
wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-client-5.5.20-1.linux2.6.x86_64.rpm
wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-devel-5.5.20-1.linux2.6.x86_64.rpm
wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-server-5.5.20-1.linux2.6.x86_64.rpm
wget http://files.directadmin.com/services/all/mysql/64-bit/5.5.20/MySQL-shared-5.5.20-1.linux2.6.x86_64.rpm

The commands are as follows:

rpm -iUh *

After installing mysql shared compact library, this was working as expected

wget ftp://ftp.isu.edu.tw/pub/Unix/Database/MySQL/Downloads/MySQL-5.5/MySQL-shared-compat-5.5.24-1.el6.x86_64.rpm
rpm -ihv MySQL-shared-compat-5.5.24-1.el6.x86_64.rpm
yum install php-mysql --skip-broken

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Here is how it can be achieved using remi or epel

/usr/bin/wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
/bin/rpm -Uvh *.rpm
/usr/bin/yum install --enablerepo=remi mysql-server.x86_64*

Using epel:

wget http://download.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm
rpm -Uvh epel-release-5-4.noarch.rpm
yum install python26

Tunneling an ssh connection through an ssh connection is completely lawful, but you need to pick unused ports for your forwarding listeners.

ssh user@100.100.100.100 -L 2201:192.168.25.100:22

then
ssh localhost -p 2201

You should end up on server B (unless something's already bound to local:2201, in which case, pick another port).
_____

There are times when you need to connect to a remote server through some other server. You can skip logging to an intermediate server and connect directly to remote server using SSH like this...

ssh -t -t root@192.168.1.1 "ssh -i /root/remote_server.pem ec2-1-2-3-4.compute-1.amazonaws.com"