Live system

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The term live system or direct start system ( AE : līv-ˈsi-stəm ) describes an operating system in computer science that can be started without installation , usually without influencing the content of the mass storage devices (e.g. hard disks or SSDs ) in the system . The entire operating system is usually installed on a bootable medium , for example on a flash memory such as a USB stick , on a CD-ROM or DVD . Or the live system is made available via the network from a server, for example within the framework of the Preboot Execution Environment (PXE), without a physical boot medium . This enables a computer to be started without a permanent memory or without a pre-installed operating system.

Containment

With live systems or direct start systems, computers without or with a damaged mass storage device or (pre-installed) operating system can also be started. They can be installed on bootable removable media .

Usually the corresponding storage medium is used. On Windows computers, the settings may have to be made in the BIOS and on Macs the C key must be pressed. After starting, a completely set up operating system environment with various application programs is available .

After removing the boot medium and restarting the computer, it is back to its original state, as the original operating system on the hard drive is usually not changed by the live system. All data of the live system has then disappeared again, since it was only written to the main memory and the hard disk is not even "mounted" on most live systems. As long as you don't do this on purpose, you can't change the data on it. Then, when using a live system, no user activities or changes are permanently saved and therefore no digital traces are left in the installed operating system.

However, you can save files to a hard drive , a USB stick or other permanent storage, e.g. B. Configuration data. These can then be used again later - after the next start-up or on another computer. (See also roaming .)

If you want to use a live system to repair another operating system on the computer, you have to mount the hard drive on which the system to be repaired is located. Once you do that, you can damage the other operating system further. With most live systems you have to obtain special access rights root account to mount and often even to access data of the other operating system .

Depending on the target group and area of ​​application, live systems are based on different operating systems and include different applications . Because no write access is required to any existing permanent storage, live systems are particularly suitable for hardware diagnostics and data recovery as well as safe Internet surfing. In order to fix errors in the operating system on the permanent storage, you usually have to obtain write access to it.

Development and Outlook

Even the first disk-oriented operating systems ( DOS ) could be operated directly from the (write-protected) start medium, which after the start did not have to be read - or only in exceptional cases. Examples are early Unix versions, AmigaOS , CP / M , MS-DOS  1.0 (1981) and Mac OS (1984), which at that time were still operated from "live disks"; this term itself was previously unknown: there was simply no other storage media, because hard drives - if they were available for the system at all - were “unaffordable” expensive. As the operating systems became more complex, installations on the hard disk later became necessary and live start media were forgotten.

Mac OS 7 then made it easy to use Live CDs . It was shipped with a bootable installation CD or multiple floppy disks . A fully functional Live CD could be created by simply moving a system folder to CD. Macintosh applications usually run without problems from a CD, since they do not depend on a writable Windows registry or the like.

With the development of Knoppix , of which there are now numerous derivatives , live CDs were met with great public interest and increased popularity .

The company Microsoft has for managing large enterprise networks Windows PE distributed (Preinstalled Environment) to developer - a non-publicly available live CD with Windows 2000 . The company was not interested in easy-to-create and easy-to-use Live CDs, as this meant that a Windows version that had only been purchased once could be used on different computers in a manner that was not verifiable for the manufacturer, which violated the license conditions if an operating system Single license live CDs are created and passed on to third parties; therefore Microsoft does not support the Bart PE project either. Of Windows Vista , however, a PE version was distributed as an accompaniment to computer magazines. In addition, Windows PE has been freely available on the Internet as part of WAIK since Vista and there are freely accessible instructions for creating a Windows PE data carrier on the Microsoft website .

The Linux operating system Mandriva Move was designed as a live system that was sold commercially. However, sales were stopped after a short time, and Mandriva has since released its live distribution under the name Mandriva One . These can be downloaded free of charge or ordered as a made-up CD. The price for the CD probably only covers the administration and shipping costs, as it is in a similar price range as for other Linux distributions on CD or DVD. It is questionable to what extent live systems can be marketed, because on the one hand there are many relatively mature, freely available variants, on the other hand the permanent use of a live CD is limited in practice to applications such as firewalls , as the content of the CDs does not change can be. For this purpose, the installation can be saved on a USB stick of any size (persistent mode, roaming ).

There is now a live version of most Linux variants for non-binding testing. Since live systems come with a large amount of software as a free download version, they are enjoying increasing popularity. In the event of a system crash or virus attack, they are an easy-to-use medium that offers a wide range of help measures.

With Damn Small Linux and Puppy Linux there are other operating systems that can be completely installed on CDs or USB sticks. Today's storage capacities of (writable) sticks and SD cards , even for live systems of DVD size, still have free space left for data, settings and additional programs. Live systems in connection with a USB stick are thus also suitable as a mobile workstation (e.g. Mandriva Move ).

Possible uses of live systems

To try

Since a live system does not have to write any data to the hard disk, it is ideal for trying out alternative operating systems without running the risk of causing damage in the event of incorrect configurations or installation problems.

System move to a new data carrier or another computer

Booted from a separate medium, the operating system (s) and data can be completely or selectively transferred to another hard drive ( migration ). The prerequisite for this is that a corresponding memory image has been created from the original data carrier by means of a backup .

Repair of an existing system

Many live systems (such as Knoppix ) contain analysis programs: In order to find and correct errors in the event of difficulties with an installed operating system, a live system is booted on a removable storage medium. For full access to the hard disks you usually need root or administrator rights. In this way, data can still be saved or the system repaired using a live CD. To save data, you only need read rights, and for repairs usually additional write rights. To avoid accidentally causing damage through write operations, live systems often only allow read access. You then have to request additional write access rights, sometimes for each file that you want to change, e.g. B. by writing in sudofront of the commands.

After an irreparable system breakdown, instead of a new installation, a previously saved memory image ( image backup ) can be written back ( restore ). After that, the restored system will be exactly as it was when the image was taken. Programs installed after the image was created are missing in a system restored in this way, which can be desirable or undesirable. If the computer was organized in such a way that the operating system and the user data are in the same partition (which is usually the case with Windows systems and by default), then all changes to the user data are lost when restoring through image restoration. It is therefore often recommended to save all of your own data in user directories on one or more partitions separate from the operating system.

Safer on the Internet

If no write permissions are granted for hard disks, it is very difficult to become permanently infected with malware via a live system from the Internet , as these are usually no longer available after a restart due to insufficient storage. A live system, however, is hardly effective against phishing .

privacy

When using a live system, hardly any or very few traces are left on the computer used. In this way, conclusions about the person or about the activities they have carried out with the computer are significantly more difficult or impossible. The Linux distribution Tails is a non-commercial live system project that is particularly dedicated to the data-sensitive use of computer systems .

Media center

A live system works well as streaming client for audio and video data, and can also act as a streaming server or for appearances as a DJ and VJ used. The dyne: bolic live system supports some of these functions.

Fight against viruses on systems that can no longer be started

The c't editorial team publishes the Ubuntu- based live distribution Desinfec't (formerly Knoppicillin ) at regular intervals , which contains Linux versions of several virus scanners and drivers for all common file systems including NTFS (Windows) and can be used for viruses and to detect and delete other malware that may have been launched from the host system. U. cannot be discovered. (Virus scanners are no longer included in the free download version for everyone.)

Live systems overview

Linux

Live systems on CD or DVD for getting to know Linux are very common . You deliberately leave the hard disk content unchanged. Most live systems can also be installed directly on the hard drive if desired and then used permanently as a full operating system.

Some examples are listed here, for an extensive list of known live distributions see List of Linux Distributions

  • Austrumi is a live distribution that specializes in low resource consumption and is based on Slackware
  • Bankix was developed by c't magazine for secure e-banking and is based on Ubuntu .
  • CentOS offers usable CD or DVD images for download as a live system.
  • Damn Small Linux is a live distribution that specializes in low resource consumption and can be booted from a USB stick .
  • From version 7, Fedora offers individual issues (spins) for each version for download, which can be used as a live system.
  • FluxFlux is also based on Slackware and also uses the window manager Openbox (for desktops, notebooks and netbooks) and GTK2 (for applications); formerly well on CD and currently (as of 2018) is on a USB stick or 4-GB SDHC cards distributed
  • Grml is suitable for system administrators and users of text-based tools, including as a rescue CD.
  • INX is a console Linux as a live CD based on Ubuntu. It is suitable for beginners who want to get to know the use of the console and its possibilities. It does not contain a graphical desktop.
  • Kanotix is a Debian based live distribution with very good support for current hardware. An installer also enables Kanotix to be installed on a hard drive.
  • Knoppix is probably the best known Linux live distribution, on DVD or CD.
  • Lightweight Portable Security (LPS) was developed by the US Department of Defense. It enables safe Internet surfing (e.g. online banking, online sessions on other computers) and prevents access to local hard drives.
  • Freespire , a free variant of the Linspire commercial operating system.
  • Linux Mint is a distribution based on Ubuntu. The actual installation of the operating system takes place via the live system.
  • Mandriva One live distribution from Mandriva.
  • Morphix is a project in which you can build your own live CD from existing modules (will no longer be developed).
  • Pardus is a sophisticated desktop operating system with excellent hardware support, which can also be used as a live system from CD / DVD.
  • Parted Magic is a GNU / Linux live system u. a. for data recovery z. B. with TestDisk and hard disk partitioning
  • Puppy Linux is a space-saving Linux distribution that can be started directly from a CD or USB stick, among other things.
  • Scientific Linux offers usable CD or DVD images for download as a live system.
  • Slack2Go was a live distribution based on Slackware with very good support for current netbooks
  • SliTaz is one of the smallest modern operating systems with a graphical user interface. It can also be installed on the hard drive.
  • SystemRescueCd is a Gentoo Linux live system. The CD was designed as a small rescue or emergency system to repair operating systems and restore data.
  • Ubuntu Privacy Remix is an Ubuntu-based live CD with the aim of providing an isolated and secure working environment for processing sensitive data.
  • Ubuntu was available on separate live and install CDs up to version 5.10, from version 6.06 onwards it is a CD / DVD from which a live system can be booted. A graphical installation is then possible via this live system. Nevertheless, there is still the option of text-mode-based installation for slower computers and special settings.
  • Vyatta Open Firmware Router is a Debian based router solution.

BSD

Windows

Other operating systems

  • AFROS Live-CD: AFROS is a completely free TOS ( Atari ) compatible operating system, for the Live-CD set on a Linux distribution as a substructure, for example Slax or Knoppix . All computers compatible with the substructure can run AFROS as a live system.
  • BeOS-LiveCD (XBEOX) and Shots BeOS-LiveCD: The basis is BeOS
  • ZETA Live CD: Successor to BeOS
  • Durafox Live Distribution : The basis is Unix
  • eComStation : ( OS / 2 successor)
  • FreeDOS : CD Distribution
  • macOS Live CD: Can be created individually with BootCD from running OS X.
  • MS-DOS : All versions can also be started from floppy disk
  • OpenSolaris Live CD
  • SchilliX Live-CD: The basis is OpenSolaris
  • Syllable Live CD

Create live systems yourself

There are now some tools that make it easier to create your own live systems:

Creation of Linux-based live CDs

  • for the Fedora distribution: Kadischi
  • for the Ubuntu distribution: remastersys (further development discontinued)
  • for Slackware: Slax
  • for Mandrake project / PClinuxOS: mklivecd
  • for the Debian distribution: dfsbuild , bootcd , remastersys (further development discontinued)
  • for the Debian distribution: Morphix , extensive tool collection and ready-made modules for creating Debian-based live CDs
  • for Dreamlinux: MKDistro
  • for Archlinux: Larch or archiso
  • for OpenSuse: SuseStudio is suitable as a comprehensive online help environment for creating live operating systems based on an OpenSuse distribution (Server, JeOS, KDE, Gnome, MinimalX)

Building Linux Live Systems on Windows

  • LinuxLive USB Creator for creating various Linux live systems on bootable USB sticks from Windows
  • UNetbootin is a tool for creating bootable USB sticks from Linux ISOs complete with bootloader. Available as Linux and Windows version. Can download a selection of distributions directly or use any bootable ISO.

Creation of Mac OS X live systems on the Mac

  • Older versions of OS X can be burned to CD / DVD using BootCD . It is also possible to create bootable flash memories.

Creation of Windows-based live CDs

literature

  • Hattenhauer, Rainer: Linux Live Systems - Knoppix, Ubuntu, Morphix, Kanotix, Mepis, Slax & Co. Galileo Press, 2005, ISBN 3-89842-631-9 .

Web links

Individual evidence

  1. Walkthrough: Create a Custom Windows PE Image
  2. Secure online banking with Bankix - c't magazine , on August 2nd, 2008
  3. c't. In: c't. Retrieved April 30, 2016 .
  4. CentOS LiveCD 6.4 Release Notes. CentOS Project, accessed October 4, 2018 . Last changed on May 18, 2013.
  5. ^ Scientific Linux Live System. Scientific Linux Project, accessed April 1, 2014 .