Author: Maurice Ruckman

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SSH Onto a Remote Server to Run Commands

Refer: http://malcontentcomics.com/systemsboy/2006/07/send-remote-commands-via-ssh.html

The basic form looks something like this:

ssh systemsboy@rhost.systemsboy.edu 'ls -l'

where "systemsboy" is actually your username on the remote host, and "rhost.systemsboy.edu" is your remote system. The command you're sending is contained in single quotes.

Here is an example sending multiple commands:

ssh systemsboy@rhost.systemsboy.edu 'ls -l; ps -aux; whoami'

wherein each command is separated by a semicolon.

Finally, here is an example sending a command that requires user interaction:

ssh -t systemsboy@rhost.systemsboy.edu 'top'

Note the -t flag. That tells ssh that you'll be interacting with remote shell. Without the -t flag top will return results after which sshwill log you out of the remote host immediately. With the -t flag, ssh keeps you logged in until you exit the interactive command. The -t flag can be used with most interactive commands, including text editors like pico and vi.

Sending remote commands via ssh is incredibly handy when writing shell scripts as it allows you to run your scripts locally even if those scripts are meant to effect changes on a remote machine. I just wrote a script, for instance, that sets up vacation mail forwarding for staff members. Without these remote commands I would have had to have staff members log directly onto the mail server and run the scripts from the command line, which I don't think they'd be too happy about. With ssh remote commands, I can give them the scripts and they can run them right from their Desktops. Believe me, they much prefer this.

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Flash Video Download In Ubuntu

After you do the below you can install the downloader:

The Download Program Itself (sudo apt-get install youtube-dl)
Refer: http://www.techdrivein.com/2013/08/best-youtube-videos-downloading-tool-for-ubuntu-youtube-dl.html

Usage:
youtube-dl -f mp4 https://www.youtube.com/watch?v=pdz5kCaCRFM

Ideas for Download Solutions:
Refer: http://www.techdrivein.com/2013/08/best-youtube-videos-downloading-tool-for-ubuntu-youtube-dl.html

How to Upgrade to Get Latest Version:
Refer: http://askubuntu.com/questions/429746/youtube-dl-stopped-working

Youtube updates his anti-download security system quite offen. You should keep your youtube-dl up-to-date. The version Ubuntu 12.04 Precis installs by default is 2012.02.27 (two years old).

You can subscribe to the WebUpd8 PPA to get new releases when they're out (that is once or twice a week) :

$ sudo add-apt-repository ppa:nilarimogard/webupd8 -y
$ sudo apt-get update
$ sudo apt-get dist-upgrade

You'll also find the .deb package of the latest youtube-dl release on that PPA (here and search for youtube-dl). Install it with a GUI-tool like gdebi or Ubuntu Software Center, or with these command lines :

$ cd directory/where/you/downloaded/the/package
$ dpkg -i youtube-dl*
$ sudo apt-get install -f

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Simple replace with sed command

Here's an example to scan/replace recursively:

grep -lr -e ' ' * | xargs sed -i 's/ //g'

Another sample:

echo "/tmp/testme.txt" | xargs sed -i 's/XXX/YYY/g'

Another sample, the dash i parameter makes it replace inline

sed -i 's|/bin/zip|/usr/bin/zip|g' testme.txt

Using sed with an input file:

sed -f sed.txt input.txt

input.txt

1 two three 1
four 5 six

sed.txt

s/1/one/g
s/5/five/

With the following sed commands

  • delete lines with [Control]
  • replace ? with a space
  • delete any lines that contain ONLY white space
  • delete any trailing white space
  • replace Word dash with a simple -
  • replace > < with ><
  • G tells sed to double space the output file

sed.txt

/\[Control\]/d
s/?/ /g
/^\s*$/d
s/:space:*$//
s/–/-/g
s/> </></g
G
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Simple Python Folder in Ubuntu

Use a bridge server to allow access to a server on your home network.

Simple script to build and start Python server:
cd ~/Documents/bookingflow
grunt
cd ~/Documents/bookingflow/build
python -m SimpleHTTPServer

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Sharing Ubuntu VirtualBox Folder with Windows

Refer #1: http://www.howtogeek.com/116309/use-ubuntus-public-folder-to-easily-share-files-between-computers/
Refer #2: https://help.ubuntu.com/community/Samba/SambaServerGuide

To start you need to right-click the folder to share and then install the software

Afterwards you'll need to change the settings to share the files:

sudo nano -w /etc/samba/smb.conf

# By default, the home directories are exported read-only. Change the
# next parameter to 'no' if you want to be able to write to them.
read only = no

# File creation mask is set to 0700 for security reasons. If you want to
# create files with group=rw permissions, set next parameter to 0775.
create mask = 0775

# Directory creation mask is set to 0700 for security reasons. If you want to
# create dirs. with group=rw permissions, set next parameter to 0775.
directory mask = 0775

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Example of a Deployment Cycle

SCHEDULE and TASKS for web deploys:

1. Start drain Cluster 1 Previous day
- Sysadmin: set node halprdjbs01/02 to disabled in mod_jk

2. Deploy eCommerce (BE) code Cluster 1 1:15pm - 1:30pm
- Sysadmin: set node halprdjbs01/02 to shutdown in mod_jk
- Sysadmin: shutdown JBoss on halprdjbs01/02
- Webdev: execute Hudson job hal_prod_cluster1_wcs_(xxx)
- Sysadmin: set node halprdjbs01/02 to disabled in mod_jk
- Webqa: smoke test HAL/SBN BE cluster 1

3. Release Cluster 1 and start drain Cluster 2 1:30pm - 1:45pm
- Sysadmin: set node halprdjbs01/02 to enable in mod_jk
- Sysadmin: set node halprdjbs03/04 to disabled in mod_jk

4. Deploy eCommerce (BE) code Cluster 2 7:00pm - 7:15pm
- Sysadmin: set node halprdjbs03/04 to shutdown in mod_jk
- Sysadmin: shutdown JBoss on halprdjbs03/04
- Webdev: execute Hudson job hal_prod_cluster2_wcs_(xxx)
- Sysadmin: set node halprdjbs03/04 to disabled in mod_jk
- Webqa: smoke test HAL/SBN BE cluster 2

5. Release Cluster 2 7:15pm - 7:30pm
- Sysadmin: set node halprdjbs03/04 to enable in mod_jk

6. Deploy code WebRes 8:00pm - 8:15pm
- Sysadmin: shutdown JBoss on halresjbs01/02
- Webdev: execute Hudson job sbnfe-prod

7. Validation testing by QA team 8:15pm - 10:00pm

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Unescape or Escape with JavasScript Solutions

Solution for JavaScript

function unescapeHTML(html) {
var htmlNode = document.createElement("DIV");
htmlNode.innerHTML = html;
if(htmlNode.innerText !== undefined)
return htmlNode.innerText; // IE
return htmlNode.textContent; // FF
}

Solution for JQuery

function unescapeHTML(html) {
return $("<div />").html(html).text();
}
function escapeHTML(html) {
return $("<div />").text(html).html();
}

JavaScript unescape() Function

var str = "Need tips? Visit W3Schools!";
var str_esc = escape(str);
document.write(str_esc + "<br>")
document.write(unescape(str_esc))

The output of the code above will be:
Need%20tips%3F%20Visit%20W3Schools%21
Need tips? Visit W3Schools!

The unescape() function was deprecated in JavaScript version 1.5. Use decodeURI()

JavaScript decodeURI() Function

var uri = "my test.asp?name=ståle&car=saab";
var enc = encodeURI(uri);
var dec = decodeURI(enc);
var res = enc + "<br>" + dec;

The result of res will be:
my%20test.asp?name=st%C3%A5le&car=saab      // Encoded URI
my test.asp?name=ståle&car=saab             // Decoded URI