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Print a process tree using ps
# ps -ejH
# ps axjf
# pstree

Type the following ps command to display all running process:
# ps aux | less

See process run by user
# ps -u username

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Checking for full words, not for sub-strings using grep -w
grep -iw "is" demo_file


Match regular expression in files
$ grep "lines.*empty" demo_file
From documentation of grep: A regular expression may be followed by one of several repetition operators:

? The preceding item is optional and matched at most once.
* The preceding item will be matched zero or more times.

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ant deploy 
ant undeploy

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Hadoop File System Commands

Syntax Overview

The basic syntax of HDFS commands is as follows:

$ hadoop fs -command [extra arguments]
For example:

$ hadoop fs -ls

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$ ec2-describe-instances # figure out instance id, eg. i-72eba2a1
$ ec2-stop-instances i-xxx
$ ec2-start-instances i-xxx
$ ec2-describe-instances 
$ ec2-associate-address x.x.x.x. -i i-xxxx # set up elastic IP again

ec2-authorize default -p 22 
ec2-authorize default -p 80

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ec2-run-instances -z us-east-1a --key YOURKEYPAIR ami-1515f67c

ec2-describe-instances i-IIII1111

ec2-create-volume -z us-east-1a -s 10

ec2-describe-volumes vol-VVVV1111

ec2-attach-volume -d /dev/sdh -i i-IIII1111 vol-VVVV1111

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3j move down 3 lines
f{ find next bracket

$1, $2, $3 refers to first, second third args
$* refers to list of all args

open -a application name_of_file
cat index.html pbcopy 
pbpaste

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Code Highlighting
{% highlight ruby %}
def foo
  puts 'foo'
end
{% endhighlight %}
 
Line number
{% highlight ruby linenos %}
def foo

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wget http://wordpress.org/latest.tar.gz
gunzip latest.tar.gz 
tar xvf latest.tar

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Find files using file-name ( case in-sensitve find)
# find -iname "MyCProgram.c"

Execute commands on files found by the find command
$ find -iname "MyCProgram.c" -exec md5sum {} \;

ssh command examples
ssh -l jsmith remotehost.example.com

Debug ssh client