Using linux' find command

Strangely enough I sometimes have a need to find a file which I don't know exactly where is. Even though I am sure I am the only one with this problem I will try to explain how to search for a file on my computer.

To make this a rather short how-to I will only give some pointers about using the find-command.

Getting stats from dd -command

While trying to move the contents of one partition to another I used the dd -command like this:
(DO NOT cut'n'paste this command)

dd if=/dev/sda7 of=/dev/sda1

Here's how to get the progress of a long dd-copy:

1. Open up a terminal (T1) and run your dd-command.
2. Open another terminal (T2) by pressing Ctrl+Shift +T
3. In terminal T2 type in: ps aux | grep dd
4. Find the Pid for the dd-command
5. In terminal T2 type: kill -USR1 <pid>
6. Go back to T1 to see the stats printed.

Repeat points 5 and 6 to keep getting an update.

Wordpress Permalinks not working?

When creating a local website on your own webserver running Apache2 and using Wordpress, you will see that the URL is created by referring to different kind of ID's. This could be Post ID's, Category ID's, Page ID's and so on. So I went into the Wordpress Administration Panel and told it to use permalinks instead. Hoping this would make the URL's a little prettier...

Remmina connection problem

After the latest update on my Ubuntu 14.04 Remmina would not connect to one of my Windows computers. I remembered having had this problem before, but was not able to remember the solution. (Even though I knew the solution was a very simple one.)

So I started googling and after a while I found the very simple solution to this problem.

LVM Snapshot example

If your Linux is using LVM (Logical Volume Management) testing out or setting up can be much safer if you take a snapshot of your root partition. Here's a small but helpful example to help you do this quickly.

Cleaning out linux-image-x.x.xx-xx-* files

I was suddenly denied access to my in-house web-server with a message telling me the disk is full. After a quick check with df -h I could confirm the root partition used 100%.
First I started to look for "user -files" I could remove, but found out there wasn't all that many of them. Most of the usage was in the folders /lib, /usr and /var. A quick question to my friend google took me in the direction that there could be some linux-image files no longer used that were spending my disk.
Some more searching gave me the following solution to removing these unused kernel files:

Making or burning ISO images

I was given a burned CD from a friend and decided to make an ISO image of that particular CD. Currently I'm using Ubuntu 12.10 and decided to use the Linux-command: dd

But to my surprise; IT WOULDN'T WORK!!! I have always used that command to make an ISO image, so now I had to figure out why this is not working, and how I could make it work.

Using netcat as a server

Just this morning I was checking out some piece of software and was trying to setup its mail configuration. But it would not function the way I thought it was supposed to so I had a look into my mail server logfile. With the tailf -command I would be seeing the messages to and from the mail server. But as I was looking at little to no action the logfile suddenly was filling my screen with messages.

Someone was trying to use my mailserver....

find files between two dates

Here's a quick tip for how you can find a file between two dates.
Suppose you are looking for a file you know you worked with last friday. At the time of writing this would be on december 7th. Using the find command you can go to your terminal and add the following code:

find . -type f -newerat "2012-12-07" -not -newerat "2012-12-08"

This would search for files acessed between dec. 7th and dec. 8th.
This code snippet also shows an example of how to use the -newerXY parameter of the find -command.

Scaling a pdf file from A3 to A4

This is just a quick tip for converting a pdf file from one pagesize to another.
By using the command convert this is easily achieved.

This is the quickest way I've found to do this:


convert -page a3 infile.pdf -page a4 outfile.pdf

The outfile.pdf should now be sized as an A4 page.
The command is as follows: convert [input file options] infile.pdf [output file options] outfile.pdf

Of course it is possible to convert to and from other sizes as well.

SSH without password prompting

Usually while working on different computers I am using SSH. Being prompted for a password is not a favourite of mine, so I set up my computers to connect without needing a password. It's easier than you think.

Password prompt via ssh

Sometimes when working with ssh you want to run a command that require root privileges on the remote host.
For instance when running apt-get install.

The trick is then to add the -t option to ssh so you get to write the remote host password.
Like this:

ssh -t example.com "sudo apt-get install nmap"

Without the -t option you would get the following error:

sudo: no tty present and no askpass program specified

Making an A5 book from a pdf-file

Here's how to create an A5 book from a pdf file. This procedure can be done by creating a script that runs through the needed steps automatically. I'll see if I will do that later. But here is the necessary steps to do this manually.

The mission is to print a folder on A4 paper, and fold it into a book.

1. Calculate:  (number of pages \ 4) + 1 = Sheets  (This is needed as the -s parameter in the psbook-command. If the original document has 9 pages then we need to use the following calculation: (9 \ 4)+1 = 2 + 1 = 3)  2 sheets will hold 8 pages which is one page less than the document. 3 sheets will hold 12 pages and is more than the document.
2. Convert the original file to a .ps-file:  pdftops original.pdf new_original.ps
3. Create the pages in the book: psbook -s3 new_original.ps new_original_book.ps   (Refer to step 1 for info about -s3 parameter)
4. Reorder the pages using psnup: psnup -l -n2 new_original_book.ps new_original_folder.ps  (Parameter -l is to print in landscape, and -n2 is to place 2 pages on each page.)
5. Convert back to pdf-format: ps2pdf new_original_folder.ps folder.pdf
6. Remove temporary files: rm new_original_*

After we have printed the book; the pages should come sequentially as in all books. Fold, staple and deliever you brochure/folder. If the original document is more than 4-5 pages we might want to cut a little in front of the book after we have folded it.

Linux Tutorials

Linux has become the preferred OS for me and my company. Not only for the fact that it is free, but also because of the possibilities it gives us.

For a small company as ours Linux is the perfect solution. It provides us with a stable and secure platform for our servers running mail, webserver, fileserver, printserver, automated backups and a lot more.

Of course we need to know a thing or two about installing it and setting up the various components . And I am always looking for more information on how to configure and setup different parts of Linux and other Open Source Software.

Recently I found out that linux.org had redesigned their site and of course I had to take a look at it.

Converting imagefiles

Using your digital camera or mobile phone makes it easy to take snapshots you want to share online, on facebook or by email. But the size of these images can be quite big since many cameras and mobile phones take pictures at 8-12 Megapixels. Then it is nice to know about the convert-command on linux that will allow you to batch convert images.

Adding an index to your pdf-file

Have you ever created a pdf-file from multiple documents? And wanted to have a clickable index for the pdf-file?
on more than one occasion have I created documents that I need to make an index to, and after some gogling I have come up with the solution that I will share in this article.
We only ned a couple of files and programs to make this work.