There are three simple steps to get a package installed, for example to install ‘build-essentials’ you would:-

apt-cdrom add
apt-get update
apt-get install build-essential

The first line tells apt to use the cd-rom as a source. Line two updates the source listings making all the packages on the cd-rom available. The third will install it as normal.

Once you have finished installing the packages you need or no longer require the the cd-rom as a source if you now have internet access you can remove it by:-

vim /etc/apt/sources

Then remove any lines that contain ‘cd-rom’, save the file and then do an apt-get update.

cat .ssh/your_key.pub | ssh user@server "cat - >> ~/.ssh/authorized_keys; chmod 700 ~/.ssh; chmod 600 ~/.ssh/authorized_keys"

Once you have run this line the next time you attempt to login (as long as your key has been loaded in to the ssh-agent) you will no longer be required to type your password.

In a future post I will be talking about further ways to secure your SSH server.

More details are available here:-

To test any website, use the great tools from ipv6-test.com

There are times you want to monitor log files and immediately see new entries as it is updated. This is easily achieved using ‘tail’.

tail is used to display the end of a file and by default shows the last 10 lines of a file using:-

tail /path/to/file

This will however not update as new entries are added to the file. To do this we add the follow option -f like this:-

tail -f /path/to file

Now this will auto update as the file is changed. We can also extend or reduce the amount of files using -n like this:-

tail -f -n 20 /path/to file

Now the last 20 lines will show. As always use the man command to find out more on what tail can do.

Zabbix is an open source, highly customisable server monitoring tool. More details are available here.

These instructions use the EPEL repository for a more upto date version than the included version in the main repos.

So lets start:-

For 32bit version use:-

$ rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-5.noarch.rpm

And for 64bit us:-

$ rpm -Uvh http://download.fedora.redhat.com/pub/epel/6/x86_64/epel-release-6-5.noarch.rpm

$ yum update

$ yum --enablerepo=epel install zabbix-server-mysql zabbix-agent zabbix-web-mysql

$ yum install mysql-server

$ /sbin/chkconfig --levels 235 httpd on

$ /sbin/chkconfig --levels 235 mysqld on

$ /etc/init.d/mysqld start

$ mysql_secure_installation

$ mysql -u root -p

mysql> create database zabbix;

mysql> grant all privileges on zabbix.* to zabbix@localhost identified by 'password';

mysql> exit

$ cd /usr/share/doc/zabbix-server-mysql-*/create/schema

$ cat mysql.sql | mysql -u root -p zabbix

$ cd ../data

$ cat data.sql | mysql -u root -p zabbix

$ cat images_mysql.sql | mysql -u root -p zabbix

$ vi /etc/zabbix/zabbix_server.conf

# line 110: uncomment and add DB password for Zabbix
DBPassword=password

$ vi /etc/zabbix/zabbix_agentd.conf

# line 91: change to your hostname
Hostname=zabbix.server.com

$ vi /etc/php.ini

# line 440: change to Zabbix recomended
max_execution_time = 600

# line 449: change to Zabbix recomended
max_input_time = 600

# line 457: change to Zabbix recomended
memory_limit = 256M

# line 729: change to Zabbix recomended
post_max_size = 32M

# line 878: change to Zabbix recomended
upload_max_filesize = 16M

# line 946: uncomment and add your timezone
date.timezone = Europe/London

$ /etc/rc.d/init.d/zabbix-server start

$ /etc/rc.d/init.d/zabbix-agent start

$ /etc/rc.d/init.d/httpd restart

$ chkconfig zabbix-server on

$ chkconfig zabbix-agent on

Once complete, open your browser and navigate to http://serveraddress/zabbix
Don’t forget to open port 80, 10050 and 10051 on your firewall.

Credit to Server-world for initial instructions, the above have been tweaked for a few things that did not work for me.

The script will parse each URL from your Instapaper account though Instapaper Mobalizer before adding it to your Evernote notebook to tidy things up a little. The page title of the website becomes the note title.

These are the steps:-

1. In Evernote create a new notebook e.g. Instapaper.
   
   
2. In instapaper, in the right hand column select ‘Export CSV…’ then ‘Download CSV file’.
3. Once downloaded, open the csv file in a spreadsheet and select only the column containing the URL’s, don’t include the 1st row titled URL. Copy the contents to clipboard.
4. Open TextEdit.
5. Create a new document then select ‘Format’ and then ‘Make Plain Text’.
6. Go ‘Edit’ -> ‘Paste’
7. Make sure you only have a text file containing a single URL perline (you may need to increase window size as long URLs will be wrapped on to a new line).
8. Save the document as ‘instapaper.txt’ to you Desktop (can be anything with a .txt file extension).
9. Open ‘Applescipt Editor’ from ‘Applications’ -> ‘Utilities’ Folder.
10. Paste the code below in to the document.
11. Modify the first line to include the name of the notebook you created in Evernote in step 1.
12. In Applescript Editor click ‘Run’. The script will then provide a file selection box where you specify the file created in step 8.
13. Once you a selected the file the script will begin running through each line of the text file, parsing it through Instapaper Mobalizer first before adding the article in to your Evernote notebook. The script waits 5 seconds before running the next line to allow time for processing. The script will automatically sync evernote when every line is done.

set myNotebook to "Instapaper"

tell application "Finder"
set Names to paragraphs of (read (choose file with prompt "Pick text file containing URLs"))
repeat with nextLine in Names
if length of nextLine is greater than 0 then
tell application "Evernote"
create note from url "http://www.instapaper.com/m?u=" & nextLine notebook myNotebook
end tell
delay 5
end if
end repeat
end tell

tell application "Evernote"
synchronize
end tell

All going well you should now have all of your Instapaper articles stored and synced with Evernote.

curl -s http://checkip.dyndns.org/ | sed 's/[a-zA-Z<>/ :]//g'

As you can see you will require curl installed, if you don’t have it type:-

apt-get install curl

nohup nice split --line-bytes=500m foo.tar.gz foo_ &

To break it down, ‘nohup nice’ runs the task in the background, ‘split’ is the command we are using, ‘–line-bytes=500m’ this defines the size of each piece, in this case 500MB each, ‘ foo.tar.gz’ the file you want to split, ‘foo_’ the starting part of each piece of the filenames, then finally ‘&’ part of the nohup.

This will create files 500mb in size named, foo_aa, foo_ab, foo_ac…….and so on.

To piece the files back together we use:-

nohup nice cat foo_a* > foo_FULL.tar.gz &

This time we use ‘cat’ and specify ‘foo_a*’ as the input files and ‘foo_FULL.tar.gz’ as the resulting combined file.

To start you can use the following command:-

find /directory/to/start/of/permission/change -type d -exec chmod 755 {} ;

In this command we are using the find command and specify our starting directory. We then specify -type d this specifies we only want directories then -exec chmod 755 {} ; is saying we want to execute chmod 755 on the results found. This will recursivly travel through our folder structure from our starting point and change the chmod on all our folders.

Likewise we can do:-

find /directory/to/start/of/permission/change -type f -exec chmod 644 {} ;

By changing -type d to -type f it will change only files to 644 and leave all the directories alone.

If you run a command and get an error such as ‘rm: Test/Downloads: Permission denied’ and you know you should have used sudo at the beginning of the command there is a quick way to correct this. Instead of retyping the command or pressing up to show the previous command and then move the cursor to the beginning and add sudo, all you need to do is type:-

sudo !!

This re-runs the previous command with sudo. Simple.