Linux Commands

Are you looking for Linux Cheat Sheet? Or most used linux commands? I am putting up a list below for my own reference that could come in handy to you as and when you need it. I hope you like it!

System Info

• date – Display current date and time
• cal – show current month’s calender
• uptime – show current server’s uptime since last reboot
• w – display which user’s are logged in and average load on the server
• whoami – who you are logged in as (funny!)
• finder username – Get information about A specific user on the system
• uname – a – Display kernal information
• cat /proc/cpuinfo – Display CPU information
• cat /proc/meminfo – Display Memory (RAM) info
• man command – Show Manual for any “command”
• df – show disk usage
• du – show directory space usage
• df -h – show all HDD’s and their mount point
• free – show RAM and its swap usage (free -m to display in MB)
• whereis app – Find location of an app

Network

• ping – ping any IP / Host and output result
• whois domain.tld – Get whois information of any domain name
• dig domain.tld – Get DNS information of any domain
• dig -x host – Reverse lookup
• wget file-location – Download any remote file
• wget -c file – Continue a paused / stopped download

File Commands

• ls – List directories
• ls -al – Formatted listing with hidden files
• cd dir – Change to DIR
• cd – Switch to home
• pwd – Show current directory
• mkdir name – Create a new directory called “name”
• rm filename – Delete a file
• rm -r dir – Delete an EMPTY directory called “dir”
• rm -rf dir – Delete an entire directory with files called “dir”
• cp file1 file2 – Copy file1 to file2
• mv file1 file2 – Move or Rename a file
• touch file – Create or Update a file
• more file – Output the content of the file
• tail file – Output last 10 lines of a file

Compression

• tar cf file.tar files – Create a tarball compressing the folder called “files”
• tar xf file.tar – Exact the tarball “file.tar”
• gzip filename  - Compress and rename the file to filename.gz

File Permissions

• 4 – Read (r)
• 2- Write (w)
• 1- Execute (x)
• Example : “chmod 777 filename” will allocation read, write & execute permission to filename.

Searching

• grep pattern files – search for a pattern in files
• grep -r pattern dir – Search recursively for pattern in dir
• command | grep pattern – Search for pattern in output command
• locate file – Find all instances of file

Process Management

• ps – Display all current active processes
• top – Display all running processes
• top -c – Display processes using top CPU
• top -m – Display processes using top Memory (RAM)
• kill pid – Kill a process with its pid
• bg – List stopped background jobs
• fg – Bring the most recent job to the foreground

SSH

• ssh user@hostname – connect to a host as a user
• ssh -p 22 user@host – Connect to a host as a user on specific port (in this case 22)
• ssh-copy-id user@host – Add your key to host for user to enable a keyed or password-less login

Shortcuts

• Ctrl + C – Halts the current command
• Ctril + Z – Stops the current command, you can resume it with fg in the foreground and bg in the background
• Ctril + D – Logout of current session
• Ctrl + U – Erase the line
• Ctrl + R – Type to bring up a recent command
• !! – Repeat the last command
• exit – Logout of current session
• abc* – Every file / dir / etc starting with abc

I hope you liked the sheet and will make use of it. In case you think I have forgotten anything, feel free to add it in the command and I will get the main sheet updated.

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cPanel hooksadmin had an unknown error

Did you get the error “hooksadmin had an unknown error” while you were trying to add the addon domain into your cPanel account? Here’s is a solution to get this fixed.

This error mostly shows up due to incorrect resources allocated to your / any cPanel account by the “root” or the “reseller”. Fixing this error is quite simple, however, the method varies depending on the roles assigned to you on the server.

If you are a reseller client

If you have purchased reseller hosting from the parent company, then you will be able to fix this error. All you need to do is, locate the account and increase the number of “addon domains” in its package. Follow these steps to fix the problem.

1. Login to your WHM
2. Click on “Modify an Account” from the left hand navigation
3. Select the account that is facing the problem and click on “modify“
4. On this page, you should see the package that has been allocated to this account. Simply increase the “addon domains” value to “1″ or as per your requirements to fix this error.

Tip - If there are quite a few accounts using the same WHM package, then simply increase the “addon domain” value in the package to mass-fix this issue.

If you are a web hosting client

If you have purchased a web hosting package from your provider, then you would not have enough of permissions to fix this error. In this case, you’d simply have to contact your web hosting company and they will get it done for you. In case they don’t know how to, then guide them to this tutorial  .

Hope this helps you fix the problem, in case if the problem persists feel free to comment below and I will help you troubleshoot it further.

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cPanel Error: Sorry, that domain is already setup (remove it from httpd.conf)

Have you received this error while trying to create an account in your WHM? You will find a lot of long methods to fix it online. However, I was pretty amazed to see the solution is very simple but not discussed anywhere. So I decided to drop a little post.
All you have to do is, run the following commands in the Shell (SSH).

/scripts/rebuildhttpdconf
/scripts/restartsrv_httpd

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How to install PDO on cpanel-WHM servers with centOS

PDO is a component that is used by CMS scripts like joomla, drupal etc. Most of the web servers would not have it enabled by default. For some reason, cPanel guys have decided to switch it off by default. Hence, if you are a server administrator and get a complaint from a client stating they are getting “PDO” related errors, then here are the steps that you can follow to get it installed. This tutorial assumes that you have a server with cPanel/WHM installed on it.

How to install PDO

• Login to WHM
• Find “easyapache (apache update)” from the left hand panel
• Click on “Start customizing based on profile”
• Select the Apache version you require. I would advise 2.2
• Seclect the PHP verson. I would recommend PHP 5.
• Seclect the PHP Build, I would advise 5.2.17
• Now scroll down to the bottom and select “Exhaustive Options List”
• Seclect “PDO” by checking the tick box next to it.
• Proceed with the recompile

Recompile may take anywhere between 10 to 45 minutes depending on the server’s capabilities. After it has been done, you need to execute following commands to restart the services:

/etc/init.d/cpanel restart
/etc/init.d/httpd restart

Now if you refresh the pages with error, it shouldn’t be there anymroe. Feel free to comment below if you have any questions or confusion.

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How to increase file upload limit wordpress on cPanel servers

Have you ever faced this problem when you’re trying to upload some file, image or anything through your wordress admin interface and it shows an error displaying very low upload limit? Well, here’s the answer to the problem which should fix it immediately.

• Copy the global php.ini from /usr/lib/php.ini to /home/*accountnamehere*/public_html. (If you do not have ‘root’ access to the server then get sample php.ini by Google’ing!)

• Nano into the php.ini file with following command. Nano is just an editor like Notepad.
  

  nano /home/*accountnamehere*/public_html/php.ini

• Now, “find” for “upload“. You can do that by hitting “ctrl+w” in nano.

• Locate the entry called upload_max_filesize and update its value to whichever you prefer.

• You will need then need to add this entry suPHP_ConfigPath/home/*accountnamehere*/public_html/ to the .htaccess file to make the server pull the information from the custom php.ini instead of the global php.ini

After making these changes, the domain should now reference the new values.

Note -

1. If you do not have “nano” installed then you can either installing by using “yum install nano” command in centOS OR “apt-get install nano” in Ubuntu. Alternatively, you can simply use cPanel code editors to perform those tasks.

2.Replace all occurance of *youraccountnamehere* to your actual cPanel account name.

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How to Install Google Chrome on Backtrack 5

This is a quick tutorial to install Google Chrome on Backtrack. A lot of people are trying to learn security these days and backtrack being one of the most used distros they download it and find themselve stuck in a dillema to use it. Here are the steps you need to follow in order to install Chrome Browser on your Backtrack 5.

How to Install Google Chrome on Backtrack 5

1. Open the Konsole – Terminal (or whatever funky name you call it with)
2. Execute the following command to download the program (apt-get install chromium-browser)
3. We need to make a few changes in the system to make it work. So switch to Chrome’s directory with following command (cd /usr/lib/chromium-browser)
4. This is the step you need to follow in order to be able to run Chrome as root user:
   - Open Hex editor with the command (hexedit chromium-browser)
   - Now search for geteuid with the command (ctrl+s geteuid)
   - Replace it with getppid and save with the command (getppid ctrl+x)

Now you should be able to run Google Chrome on your Backtrack 5 along with root privileges.

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How to hire an SEO expert?

Search Engine Optimization is now being considered as one of the most important marketing strategies by in all kinds of industries. A lot of people think that SEO is a simple process and try to do it themselves, a few days later, they realize that this ain’t their piece of cake. Now its time to hire someone who can do it for them. While drafting this paragraph, I remember my uncle so I am going to bore you with a short story.

This uncle of mine doesn’t know a lot about computers, yet he has the desire to learn everything and become “Expert of all“. He would sit on his laptop all day god knows what he does. One day he called me asking if I can help him a bit with SEO. I told him that “the process of SEO is simple, however, the order of the procedure varies depending on the market, compeition etc etc.” A month later, I get another call from him “Beta, I spoke to google guys over the phone (kidding me?) and they said they can get my website on top of Google within a month, it is guaranteed. Since my business can do well if its doing good on Google, I paid themRs.50,000/- for 1 month. Now, my site is no where near even the 3rd page and they are not picking up my phone calls.” All I had to say was “I will write a small blog post to guide you and other fellows like you”. Which I thought of doing tonight!

Getting back to the business, I always advise my friends , relatives to not to play around with the productive stuffs. For example, if you want to learn SEO then simply set up a new domain and do whatever the heck you want with it, instead of screwing over your business website. As SEO evolved into a whole new industry creating thousands of jobs, a lot of scammers also jumped in the wagon as there are no specific metrics for SEO. In this article, I will discuss a few points you can consider before hiring someone for Optimizing your website.

Preparations

1. Analyzing the scope:

Having your website listed on top of Google pages could be good for your business, however, not every industry gains expected economical benefits from it. The very first thing you need to do is “CALCULATE”.

• If you spend X amount on SEO for X months, and you get X visitors per month, how much could you actually make?
• Is it even worth distracting yourself from core business?
• Estimating the months it could take to recover your investment for optimization (afterall, its all money right?)
• If your website ranks #1 on Google, what benefits will you get?

Once you have answer to these questions, the picture would be much more clear to you. You would have exact idea about the amount you’re to invest and returns you’re expecting. Ofcourse both the amounts are variable, but having an “idea” is always better then “A blind date with SEO expert”! 

2. Resources to tweak the website:

I assume you already know that SEO is done onsite as well as offsite. Offsite is pretty much handeled by your SEO expert and doesn’t require any changes to your websites in most of the cases. However, ONSITE SEO (being an important factor) would require a lot of changes within your website’s structure. Here, you need to ensure that you do have the resources to tweak your website accordingly, in case you don’t then you need to confirm it with your SEO Expert that he will have someone do it for you.

Hiring Procedure:

1. Shortlising Companies:

There are a lot of local SEO companies available these days in almost every part of the world (The part thats on Internet). As per my knowledge, most of the Local companies are not worth spending your money. Ofcourse there could be exceptions to this, however, most of the SEO companies that I’ve come across in Mumbai & Delhi were pure bullsh1t. The simple solution to this problem is , Google! – Since you are trying to hire someone who will help you rank your website in Google, why not just search on Google and make a list of people who’ve already done it for themselves! Afterall, a Doctor who can’t cure his wife’s fever is of no use right?

2. Call them:

You never want to fall in trap of those “one man show SEO” type of companies. They are mostly run by a single person who has multiple projects in hand. Those kind of companies would always be nice when you are in the “negotiation” phase, but once the money is paid, you will see totally changed man! Hence, its always better to call the companies directly and have a word with them to understand how serious they are.

3. Ask for references:

Almost every SEO company would have glittering “its all good” kind of testimonials on their websites. Being a businessman, you already know that its more of marketing then actual appraisal. While you’re on the phone with your potential SEO vendor, you should ask them to provide you with a couple of references around the same location as yours. Be clear that you’re willing to discuss further only in case they are willing to fulfill your reuqest of reference. Otherwise, this deal stops right here.

4. What can they do for you?

Almost every SEO expert guarantees to rank your website in top 3, which is not the case. So don’t just hold him accountable for the 100% ranking gurantee. Ask him questions, where should you see your website in a couple of months. Ofcourse, SEO ain’t simple as math, so results may vary, but its good to have a goal and then chase it. In case your SEO expert asks you to leave the technicalities to him and just enjoy the results, ensure atleast you know what is he going to do. There are a few companies which execute unethical methods to rank your website. Their methods do work, however, a few months later, your website would not be seen on google at all (Search for “sandbox” to understand).

I hope this article was a gist of what you were looking for. Hiring an SEO expert is really a task because the person you hire will decide the fate of the online presence of your product / brand. If you are a businessman and don’t know technical stuffs, involve your friends , relatives. Ask your Son! If he’s good with computers, he would know more about SEO then you do. Feel free to comment below if you have any questions. Not that you can’t comment otherwise! 

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