Set tab width in VIM to 4 spaces or a single tab


Vim by default adds two tabs when you indent something. It also messes up the whole thing if you paste a large code block with tabs into it.

Here's how you can set the tabs to 4 space width, and fix that messing up issue.

Edit your vim config file and add this at the bottom of it.

vim ~/.vimrc

and add the following.

set tabstop=4

Now save and quit. Start vim to see that it now indents your code only by a single tab :)

Convert putty ppk key file to public, private key pair to use in SSH client Ubuntu

Convert putty ppk key file to public, private key pair to use in SSH client Ubuntu


Today, a friend asked me to login to a Linux server and he sent me a PPK file which he uses with his Putty client in Windows. I had to generate a Public / Private key pair from that PPK file in order to use it with my SSH client in Ubuntu. It was really easy and took me only a few minutes. I thought I should post this in my blog so it would be helpful to somebody, and it would also be useful to me as a quick reference in future whenever I need it again.

This is how to convert your PPK file to an OpenSSH keypair.
  1. First, if you don't have putty tools installed in your computer, you have to install it. This will help us when dealing with PPK files.

    sudo apt install putty-tools
  2. Now we can use the puttygen utility to generate an OpenSSH private key from this ppk key file. To do that, run the following command.

    puttygen <your-key-file>.ppk -O private-openssh -o <new-key-file>
    Ex: puttygen key.ppk -O private-openssh -o id_rsa
    Here the -O option stands for "output-type" and it specifies the type of file we want to generate. By giving it as "private-openssh", we tell it to generate an OpenSSH private key file. You can see the manual page by running man puttygen if you want to learn more about the other output types. (But they aren't required now).

  3. Okay, now we have the private key. We can use ssh-keygen to generate the relavent public key for this private key file.

    ssh-keygen -y -f <new-key-file> > <new-key-file>.pub

    Ex: ssh-keygen -y -f id_rsa > id_rsa.pub

    Here the -y and -f options mean the following: (taken from the Manual page)

    -y = This option will read a private OpenSSH format file and print an OpenSSH public key to stdout.
    -f filename = Specifies the filename of the key file.


    I hope it's clear. We are almost done.

  4. Last step is to set the right permissions for the new key pair. Usually, the SSH client expects the Key files to have permission as 400 or 600. So let's set it.

    chmod 400 id_rsa
    chmod 400 id_rsa.pub
    Now we should be able to login to our server using the new key pair we generated.

    ssh -i .ssh/do_server/id_rsa root@xxx.xxx.xxx.xxx

I hope this will be useful to somebody in future :) If this post helped you, don't forget to leave a comment and let me know !

GMAIL Mailbox names for IMAP connections?

GMAIL Mailbox names for IMAP connections

I worked on something interesting today. That was "creating a simple email client for Gmail", using the PHP's built-in IMAP library. I know there is an official PHP library provided by Google for that, and I have even wrote a blog post about it sometime back (explaining about a bug I found in it). But this time I wanted to do it with the Imap library instead.

So soon after finishing the Inbox, I started working on listing the "Sent Items". But to my suprise, I had a bit hard time finding the right mailbox name for the sent items. I assumed a few names like "Sent", "Sent Items", "Sent Messages", but none of them worked. So I turned to Google and did some search, and then I found this page on the Google Developers website.

https://developers.google.com/gmail/imap/

It explains everything about Gmail and the IMAP protocol, and how to actually use IMAP with Gmail. In the IMAP Extensions page, they have listed all the mailbox names and it was just a matter of using the right name.

Here's the list:


a004 LIST "" "*"
* LIST (\HasNoChildren) "/" "INBOX"
* LIST (\Noselect \HasChildren) "/" "[Gmail]"
* LIST (\HasNoChildren \All) "/" "[Gmail]/All Mail"
* LIST (\HasNoChildren \Drafts) "/" "[Gmail]/Drafts"
* LIST (\HasNoChildren \Important) "/" "[Gmail]/Important"
* LIST (\HasNoChildren \Sent) "/" "[Gmail]/Sent Mail"
* LIST (\HasNoChildren \Junk) "/" "[Gmail]/Spam"
* LIST (\HasNoChildren \Flagged) "/" "[Gmail]/Starred"
* LIST (\HasNoChildren \Trash) "/" "[Gmail]/Trash"


https://developers.google.com/gmail/imap/imap-extensions

The mailbox name should be the name you see inside the square brackets. ex: [Gmail]/Sent Mail

Here's how to use it:

$hostname = '{imap.gmail.com:993/imap/ssl}[Gmail]/Sent Mail';

I thought I should post this in my blog, hoping that it would save someone else's time :) Please don't forget to leave a comment if it helped you. :)

Change prompt in Ubuntu terminal - Hide hostname and working directory.

Oftentimes, I use Tmux to split my terminal windows to save time from switching between them. Although that was quite nice and useful, I always had one problem when working inside some directories located deep down my directory hierarchy. That is, whenever I split up my terminal, I'm always left with a small window for each terminal. So when I'm inside the deeper directories, the prompt takes much longer space to show the path and my prompt was always kept at the end of the window. That was really inconvenient.

Here's how it looked like:

Change prompt in Ubuntu terminal - Hide hostname and working directory.

I came up with this solution to get rid of that problem. I decided to change my prompt so it would only show my username and current directory instead of the full path. That would make my prompt very shorter and hence I would have enough space to type in my commands and see it all clearly. I was a little bit concerned about this as I still wanted to see my host name whenever I'm connected to a remote server through ssh because I often connect to multiple servers at once so it's important to see which server I'm in before running any commands. Anyway I realized I could make this change available only for my local user account so the usual prompt will be available to me whenever I'm connected to a ssh session.

Here's how to do that.

First edit your .bashrc file in your home directory.

vim ~/.bashrc
Locate the following code block.

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

You need to change the PS1 line to change the prompt. By default it is in username@host:workingDirectoryPath format. Here's how I have changed them.

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u:\[\033[01;34m\]\W\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@:\W\$ '
fi

If you notice well, you will see that I have removed the h and replaced w with W (which means hostname is removed and the full directory path is replaced by the current directory).

Save the file and quit vim.

Now we need to reload the bash configuration for our current terminal session. Just run the following command to load your new configs.

source ~/.bashrc
Once you run the above command, you should immidiately notice that your prompt is changed :) But now you won't see the full directory path in your prompt. You can still see it by running the following command.

pwd
Here's how it looks now.

Change prompt in Ubuntu terminal - Hide hostname and working directory.

That's it !! I hope this will be useful to someone. Please feel free to comment and let me know if I have missed anything or if you know a better way to do this.

Maria DB Fix - ERROR 1698 (28000): Access denied for user 'root'@'localhost' on a new installation.

Maria DB Fix - ERROR 1698 (28000): Access denied for user 'root'@'localhost' on a new installation.


Today I installed MariaDB on my laptop and faced this weird issue. After the installation, I tried to login to the DB shell using the user 'root' and the blank password. Then it returned me this error message stating:

ERROR 1698 (28000): Access denied for user 'root'@'localhost'
My first guess was that they might have changed the default password and set it to something else. So I did some research and realized it was not the case here. The actual problem was related to the authentication process of MariaDB.

MariaDB uses a plugin called UNIX_SOCKET to authenticate users, which allows them to use the operting system credentials to login. If I wanted to login to MariaDB using the root user, it first requires me to logged into my system as root (which I can temporarily take access using the sudo command.)

But since I'm logged in as the user nimeshka, I cannot request MariaDB to login as another user (in this case, root). So if I enter the command,

mysql -uroot -p
it would tell me that I have no permissions to login. Why? because I'm authenticated to the Ubuntu system as nimeshka, so MariaDB won't trust me when I ask it to login as root :P So it is clear that if I enter the following command, it would allow me to log in.

sudo mysql
You should also note that If I had created a user in mysql with the username nimeshka, I could have logged in to the shell by just entering the mysql command (it will take my current system username and will log me in as the particular mysql user)

Another thing to note: As I was concerned why I didn't face this issue when I installed MariaDB earlier, I looked for a bit more details in their documentation and found a satisfying answer. It says that they use the UNIX_SOCKET plugin by default in new installations of Ubuntu 15 and later (I used to install MariaDB in Ubuntu 14 earlier and today I tried it in Ubuntu 16, which makes sense!).

So here is how to disable the UNIX_SOCKET plugin for root user.

# First we will login with sudo (means root)
$ sudo mysql -u root

# Then switch to the mysql DB.
MariaDB [(none)]> use mysql

# Then we will update the authentication plugin for root user by running the following query.

MariaDB [(none)]> update user set plugin='' where User='root';

# We need to flush privilages and exit the session.
MariaDB [(none)]> flush privileges;
MariaDB [(none)]> quit


That's it guys, hope this will be useful for someone :)

Hide recent files in Ubuntu Dash search.

By default Ubuntu shows file results and recently accessed files in the dash. Although it's useful, there are times it becomes annoying to the point that you wish if you have an option to disable / hide these files from the dash.

Luckily, it's something very easy to achieve. Here's how to do it.

Just press your super key (Windows key) and type privacy into the dash search box. You will see a result similar to the image shown below. (Icons could be different depending on your theme. However, you need to select the "Security and Privacy" app.



Hide recent files in Ubuntu Dash search.

Then once you open it, click on the "Files & Applications" tab (second tab). Here you can disable the "Record file and application usage" option to ask Ubuntu to not remember your actions. If you still want it, and just want to ignore specific file types, you just have to uncheck the file types you want from the list shown below in this window. 



Hide recent files in Ubuntu Dash search.


You can also clear all your recorded usage data so your dash will not have any past data :)

That's it guys. I hope it's clear and helpful. Please don't forget to leave a comment if this was helpful to you!!

Customize Gmail's new Material UI to look better!

gmail-new-material-design
Good news folks, Gmail launched it's new user interface with a cool material design a few days ago and I promptly switched to it. Like every other web developer who questioned "why Google doesn't introduce the material design UI to Gmail?", I too was concerned on the same, and I knew it would be there someday soon. Now it's released and I'm happy with the new version so far. It looks good, user friendly and not so heavy on the browser (surprisingly).

However, reminding us all that nothing is perfect, I found that a few elements of the new UI are not up to my tastes (Seems a bit difficult to read, specially the bold subjects and the font size). So I changed it to make it look how I like. If you too want to make some changes to it, this is how I did it. It's really easy, but I did this in Firefox <3 only.

So what we are going to do here is apply a custom style sheet on top of the Gmail interface. You can do it easily in Firefox. Remember, we apply the changes to the browser, not to the web page itself. So we need to change the browser's style sheets, which will be applied to the websites we ask on it.

First select Help -> Troubleshooting information from Firefox tool bar. It will open you a page with some configuration values table. In the table, under the Profile Directory row, you will see a button named "Open Directory".

Firefox-troubleshoot-information




Click on it and you will be taken to your Firefox profile directory. Now create a new directory and name it as "chrome" (If this directory already exists, you can skip this step.)

Additional Info: For those who wonder, "chrome? in Firefox? why?". Here's the answer: In GUI terms, a window of an interface is usually known as a chrome. So this is not making any references to Google Chrome ;)

Now, inside the new directory you created, make a new file and call it as "userContent.css". You can add the following styles to it to make any changes you wish to see in Gmail interface.


@-moz-document domain('mail.google.com') {
    .yW {
        font-size: 15px !important;
    }
   
    .zA > .a4W {
            font-size: 15px !important;
    }

    .zF, .bqe, .bq3 {
            font-weight: 500 !important;
    }
}


What's important here is that, you have to write all your styles for Gmail within the outer css rule. That is: @-moz-document domain('mail.google.com') {}.

Now if you restart Firefox and access Gmail, you will see your fonts are a little bit expanded and very readable. I also changed the font-weight to 500 to reduce the boldness.



If you are used to the old Gmail interface and it's fonts, I recommend to change the fonts to "Sans Serif", but if you do so, remember to change the font-weight ;)

As you might have already guessed, you can use this same method to apply custom styles to any website you want :) Just change "mail.google.com" to  whatever the domain name you wish.

That's it guys! I hope this post is clear. Please feel free to ask anything on comments and don't be hesitant to point out if I have done anything in a wrong way :)

Download a list of files using a shell (bash) script.

Download a list of files using a shell (bash) script.


Today I'm going to share something interesting which will help you to download a large number of files at once. For one of my projects, I had to find images from Google, and upload them one by one to a particular website and create posts. At first, this was not much difficult as the number of images I needed was very little. But it kept growing and growing and I had to manually do the same thing repeatedly. Since I'm a lazy person by nature, I wanted to automate the process and here is a part of it, which I did to download the images quickly.

Unfortunately I couldn't automate the Googling part because it needed some human eyes to find quality images (I didn't want to go to the level of automation using computer vision ;) ). So however I searched for images, then whenever I found an interesting image, I right clicked on it and opened the image in a new tab (using ctrl + click). I kept doing this until I had enough images.

Here's the interesting part:

I installed this awesome Firefox extension in my browser, which allowed me to copy all of the URLS which were currently open in my brower. That was very convenient given that I had to copy each URL one by one when I began this task.

So now I have a list of URLS of the images I wanted to download. Now what? I pasted the copied list to a text document and opened another text document to write my shell (bash) script. So here it is.

#!/bin/bash

file="urls.txt"

while IFS= read line
do
    echo "$line"
    wget "$line"   
done <"$file"

Explanation: First I assign the name of the file I want to read into the file variable. Then I simply read the file line by line and run a wget command with the url to download the file.

To run this script, all I had to do was fire up a terminal, grant the execute permissions to the file and run it using the following command.

$ ./download.sh

download.sh is the name of your shell script.

That's it folks. I hope this will help someone :) Please leave a comment if you think this helped you or if you think I miss anything.

Solved - How to exit a telnet session?

How to exit a telnet session?
How to exit a telnet session?
It's funny, but I was fumbling with the terminal to exit a telnet session today. I rarely have to use telnet so I'm not much experienced with it. But if someone ever want to exit from a telnet session this is what you have to do.

Basically when you start a telnet session, this is what you would see most of the times:

~$ telnet localhost 80
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.


Now what? Pressing Ctrl + c, z, x, d will not do anything. I was too lazy that I didn't pay much attention to what was printed in the console. If I had read that, I would have easily exit the session.

It says:  Escape character is '^]'.

So that's it. You need to press Ctrl + ] keys and it will take you back to the telnet prompt where you can either press Ctrl + D or enter the command "quit" and press enter.

~$ telnet localhost 80
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
^]
telnet> quit
Connection closed.


One thing to note is that I use Terminator as my terminal emulator and this method doesn't work in it. I Still can't exit from that (: But this definitely works in the gnome terminal.

I hope this will help someone :) Please don't forget to leave a comment if you ever come across this post. Feel free to correct me or add any methods you know other than this.

Fix libQt5Charts.so.5: cannot open shared object file error with Redis Desktop Manager in Ubuntu



A few days ago, I was looking for a Redis client for Ubuntu and found that there is one called Redis Desktop Manager. Although it's free and open source, it only provides builds for Windows. Ubuntu and Mac OS users have to subscribe by making a monthly payment or they can build it by themselves using the source (: So I opted for the second option and built and installed it in my Ubuntu box since it was for a small task.

Then today, when I tried to run the RDM again, I got this error and I was wondering what might have changed in the system. In fact there was nothing changed so I had to dig a little bit more into the error and found why I got this error. So here's how I fixed it.

If you haven't built the Redis Desktop Manager (RDM) by source before, this is how to do it. (It's all well documented)

~$ git clone --recursive https://github.com/uglide/RedisDesktopManager.git -b 0.9 rdm && cd ./rdm

~$ cd src/
~$ ./configure
~$ source /opt/qt59/bin/qt59-env.sh && qmake && make && sudo make install
~$ cd /usr/share/redis-desktop-manager/bin
~$ sudo mv qt.conf qt.backup

Now it's done and you can simply run RDM by entering the command:

~$ cd /usr/share/redis-desktop-manager/bin/
~$ ./rdm

or simply by using:

~$ sh /usr/share/redis-desktop-manager/bin/rdm.sh
I believe that you are reading this blog post means you got either of the following errors when you run the above command:

/usr/share/redis-desktop-manager/bin/rdm.sh: 2: /usr/share/redis-desktop-manager/bin/rdm.sh: source: not found
/usr/share/redis-desktop-manager/bin/rdm: error while loading shared libraries: libQt5Charts.so.5: cannot open shared object file: No such file or directory

or just:

./rdm: error while loading shared libraries: libQt5Charts.so.5: cannot open shared object file: No such file or directory
It says it's unable to load the libQt5Charts.so library. So if you are sure that you have installed (I bet you have) and still get this error, you need to do a few things before running RDM.

First you need to tell it where you have the QT libraries. When you build from the source, the QT libraries are installed at /opt/qt59 directory.

So just enter the command

~$ source /opt/qt59/bin/qt59-env.sh
Now if try to run RDM again, it should work fine :) Since this seems reduntant for us to enter this command everytime we want to run the Redis Desktop Manager, you can edit the rdm.sh file and add the above line on top of it.

Note: If you paid enough attention to the build process, you may have noticed that we ran the above command during building it from the source. That's the reason why it worked a few days ago when I installed it.

So let's update /usr/share/redis-desktop-manager/bin/rdm.sh file.

~$ vim /usr/share/redis-desktop-manager/bin/rdm.sh
#!/bin/bash
source /opt/qt59/bin/qt59-env.sh
DIR=$(dirname "$(readlink -f "$0")")
export LD_LIBRARY_PATH="$DIR/../lib":$LD_LIBRARY_PATH
$DIR/rdm

Notice that we added the line: source /opt/qt59/bin/qt59-env.sh after the shebang. Now save it by pressing ESC then :wq in vim and RDM should load fine :)

I also found that having to enter long paths to run RDM is overkill. So I just added a softlink to my /usr/bin directory using the below command.

ln -s /usr/share/redis-desktop-manager/bin/rdm.sh /usr/bin/redis-desktop
Now I can run Redis Desktop Manager using the redis-desktop command.

That's it folks. I hope this will be helpful to someone. Please don't forget to let me know if I have missed anything, and leave a comment if you know a better way to do this.