Introduction to terminology

Configuring Knoppmyth and Linux in general can seem very complicated at first because there is so much unfamiliar terminology. Given that Linux programs are all written by geeks many of them have been given rather unfriendly names that are not self-explanatory. Futhermore because we are inherently lazy all of this terminology is then abbreviated. For example "mkisofs" stands for "make iso file system".

I strongly recommend finding a good Unix tutorial like this: http://www.ee.surrey.ac.uk/Teaching/Unix/

Or this online guide to Debian systems administration: http://colt.projectgamma.com/debguide/hands-on.html

Conventions

• Note that in Unix/Linux case matters! For example "aaa", "Aaa", and "AAA" are three different things. About the only place it doesn't matter is in hostnames and email addresses for historical reasons I won't go into.
• In the examples below ' = ' with spaces around it is generally used to seperate the example command from the explaination. A better thing to do would be to have used the # which makes the rest of the line a comment in all shells. However I don't have time to fix this now...

Some Basics

• PVR = Personal Video Recorder
• HTPC = Home Theatre PC
• distro = a Linux distribution such as Knoppmyth, Knoppix or Debian
• GUI = graphical user interface
• UI = user interface
• X (or X Windows) = a portable, network-transparent window manager. It and the fluxbox desktop manager are the GUI platform that Knoppmyth uses. Other popular Linux desktop managers are Gnome and KDE.
• the frontend = what you see, the graphics, the MythTv interface
• the backend = the geeky stuff going on behind scenes
• the kernel = the 'brain' of the Operating System. This contains device drivers for hardware.
• lilo = this is the name of the bootloader that Knoppmyth uses
• cache = A memory area where frequently accessed data can be stored for rapid access.

Terms used to describe "Command Prompts"

• console
• x-term shell
• bash
• ssh
• $ indicates that you are logged on as a normal user
• # indicates that you are logged on as root/super user/administrator

Some Common Program Names

Some programs are used by MythTv and so you will be using these without realising it, e.g:

• Xine = A program used by MythTv to play DVD's
• Mplayer = A program used by MythTv to play compressed video files
• ivtv = A program used by MythTv for Tv Playback

Then there are numerous programs for you to use when fiddling around with command prompts... i.e. configuring/fixing/optimising your system.

• nano = a program used to edit text
• vi = another popular text editing program
• apt-get = used to auto-install software packages

Getting to a Shell

You may have gathered that Linux is based on keyboard commands rather than the MS based 'point and click' style. You can get to a command prompt in various ways:

1. Hold down CTRL ALT and (F1). F1-F6 will also work. These screens are called consoles. F7 is reserved for X Windows which is what the mythfrontend runs on. Hold down CTRL ALT and (F7) to exit the console.

2. If you exit MythTv (i.e. the mythtv frontend) you will arrive at the X Windows Desktop. If you right click a menu will appear from which you can select XTerm. An Xterm shell custom essay will appear, this is therefore a command prompt screen ontop of the X Windows GUI.

3. If your mythbox is connected to a network then you can access the mythbox from another PC on the network. This can even be done on a Windows PC using an application such as Putty.

Using Command Prompts

Linux commands are always abbreviated and geeky looking which makes them look scary at first. They are also very mathematical/logical which can also scare people away. However once you sit down and practice a few commands you will discover that it is surprisingly a lot quicker to navigate and manipulate a PC using a keyboard than it is to use a mouse. It also makes you look really clever.

The Basics.... getting started:

If you type out the first few letters of a long filename press the TAB key. This will either complete the word for you or (if pressed repeatedly) provide a list of possible filenames you are after.

You may also realise that some guides/solutions will tell you to type in longwinded commands which will "bend your head" if you try to type them in manually. The easiest way to play is to access your mythbox from a Windows PC on the network using a client such as Putty. This means you can surf the net on the Windows PC and just copy and paste commands into the mythbox via Putty.

Becoming the Super User aka "root".

1. su - = switch user to root

Also see these details directions on how to BecomeRoot.

Moving between Folders

1. cd = changes the directory
2. cd .. = goes back a directory (up a level)
3. cd / = goes to the root directory (top level)
4. cd /myth/video/Simpsons = go to a directory regardless of where you are
5. cd video/South Park = go to a directory relative to whereabouts you currently are

Listing Directories/Folder Contents

1. ls = this will list everything in the current directory
2. ls /cdrom = lists everything in the cdrom directory
3. man ls = opens up a user manual for more uses of the ls command

Creating Folders/Files

1. mkdir = makes a directory
2. mkdir "South Park" = Creates a folder in the current directory. The speech marks are needed if there is a space in the filename.
3. mkdir /myth/video/"South Park" = Creates a folder in the specified place regardless of where you currently are.

Note that creating files or directories with spaces in their names is generally considered a bad idea in the Unix world because it complicates scripting enormously.

Removing/Deleting Folders/Files

1. rm /myth/video/Simpsons/ep01= deletes the specified file
2. rm -r Simpsons = deletes a folder contained in the current directory. The -r means recursive and is needed in order to remove the contents of the folder.

Copying/Backing up Folders/Files

1. cp channels.conf channels.conf.bak = duplicates a file in the current folder. People use things like .bak or .old to indicate that it is a backup file.
2. cp channels.conf .. = copies a file in the current directory to a directory one level up
3. cp * /myth/video = copies everything in the current directory to the specified directory (excluding subdirectories/folder contents)
4. cp -r * /myth/video = as above, except this will also copy subdirectories (the contents of any folders)

Moving Files/Folders

1. mv channels.conf /usr/src/channels = moves a file in the current directory to the specified directory
2. mv /usr/src/timmy/channels.conf . = moves a file from a specified directory to the current directory ('.' is an alias for here)
3. mv -r /cdrom/timmy /myth/music = moves a folder from one place to another

Creating symbolic links

A symbolic link is a directory entry that points to another filesystem object (file, directory, device, ...) by name. If another directory entry already exists with the same name, you must either delete it first, or use "ln -sf" to force the replacement.

1. ln -s /dev/hdc /dev/dvd = creates a symbolic link for the name "dvd" to another filesystem entry "hdc" (here a real device)
2. ln -sf /dev/hdc /dev/cdrom = creates a symbolic link for the name "cdrom" to the device "hdc". Note the use of the flag "-f" to force removal of any previous entry.
3. ln -s .mythtv/lircrc .lircrc = creates a symbolic link for the name ".lircrc" to the file ".mythtv/lircrc"

You can delete a symbolic link with "unlink".

1. unlink /dev/cdrom = removes the symbolic link to "/dev/hdc" in the above example.

Unzipping Files

Whenever you want to uncompress a file you will realise it looks a bit trickier than using WinZip. You will see things like tar, bzip, gunzip etc and many variations as to how you can uncompress these files.

1. gunzip Mplayer.tar.gz = produces an uncompressed tar file - use with .gz files
2. bunzip2 Mplayer.tar.bz2 = produces an uncompressed tar file - use with .bz2 files
3. tar xf Mplayer.tar = unpacks the multi-file archive
4. tar jxf Mplayer.tar.bz2 = uncompress (bzip2 compression) and untar in one
5. tar zxf Mplayer.tgz = uncompress (gzip compression) and untar in one

The Pipe Symbol

The Pipe Symbol | is used to feed the output of one program into another. Sounds mathematical and geeky but it is quite easy and very helpful, eg:

1. ls /cdrom = this might list hundreds of files (that you cannot see on one screen)
2. ls /cdrom | more = the more program takes the list of files and allows you to wade through them page at a time
3. ls /cdrom | less = a bit like the more command, only different

For more auto insurance quotes on redirecting input and output see the IORedirection page.

Editing Files

This is generally just a matter of invoking one of the editors mentioned above with the name of the file to be edited. For example:

nano /etc/modprobe.conf

Nano is pretty basic, and has lots of onscreen help, so the rest should be fairly obvious. Note that "^X" is conventional shorthand for Ctrl-X (Hold down the "Control/Ctrl/Ctl" key and hit the "X" key). For more detailed directions see the EditAFile page.

Combine Files

If you find two files you need to combine, it can easily be done with "cat". This works great with mpg files when a recording ends up in two files.

1. cat file1.mpg file2.mpg > file3.mpg = Adds file1 & file2 to create file3

Recovery Methods

There are various ways to recover your system if mythtv crashes.

This will take you to the Knoppmyth logon screen.

CTRL ALT BACKSPACE

This the Linux equivalent of doing CTRL ALT DELETE and Task Manager. This will list everything in memory.

• # ps -A

You may have loads of stuff in memory in which case use this to wade through page by page:

• # ps -A | more

You will see that each program in memory has a number assigned to it in the list. To terminate a program do, for example:

• # kill 9420

Manual Reboot/Shutdown

If you are not logged in as root/super user then do, (note that the trailing dash matters):

• $ su -

Reboot is as simple as:

• # reboot

And to shutdown just do...

• # sudo halt

The Layout from the root directory

If you are used to using Windows XP you may know that:

• C:\Windows = stores the Windows OS
• C:\Program Files = most software installs itself in here
• C:\Windows\System32 = stores device drivers
• C:\Documents and Settings = stores your desktop/user preferences

Naturally with Linux you have to learn a different architecture which will probably baffle you at first. If you run "ls /" from a command prompt then you will see all everything on your mythbox hard drive (at the top level):

• /boot/ = stores stuff related to booting the system up (e.g. the kernel and lilo bootloader)
• /bin/ = a reference for commands/installed programs
• /dev = a reference of all devices/hardware on your PC
• /etc/ = miscellaneous stuff
• /home/ =
• /lib = libraries
• /myth/ = this is where all your media files are stored
• /proc = stores a 'reflection of what is in memory' - useful for kernel information and system processes
• /usr = unix system resources (pronounced user)
• /var = variables -- i.e. files that are always changing

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Some common places to visit

/usr/src = Knoppmyth stores various source code packages in here. These are the source packages buy phentermine from which your version of Knoppmyth was built. They are useful if you want to reconfigure and recompile a particular program for some reason.

/usr/home/mythtv/.mythtv =

/etc/X11/ = The XF86Config-4 file in here contains all of your current Display Settings (resolutions etc) and has various sample files.

/usr/local/share

How can I see how much of my resources (processor, memory, etc) are used during recordings?

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• $ top

(q to quit)

How do I check the disk space usage?

You can do this from the mythtv frontend under Information Centre, System Settings. Alternatively if you want to be a nerd about it:

This will show the amount of space used on each disk

• df -h

This will show the amount of inodes used on each disk (the video drive can sometimes report out of disk space when it runs out of inodes.)

• df -i

This will show the amount of space used in /myth and each of its subdirectories.

• du -h /myth

Another alternative is to use "ls -Slah |head". This will show in descending order the largest file sizes in a directory.

How do I turn off the console blank?

• $ setterm -blank 0

Learning more about Linux on The best way to learn is by searching Google for relevant information. Do a search for "linux newbie" and begin looking at pages for one that fits your needs. You can also find a great deal of Linux documentation at The Linux Documentation Project and auto insurance quotes

<rewritten by Nick Parkinson whilst bored and unemployed on the 25/10/2005 -- UK date format that is>