Also, running an OS from a USB drive is slower than from a hard drive, so don't judge Linux Mint's performance based on this experience. When you're ready to take the plunge, double-click on the Install Linux Mint icon on the desktop to kick off the process. Using a Mac with at least OS X 10.6.8 installed, access the Mac App Store and download the Lion (10.7) or Mountain Lion (10.8) app installer. Insert the USB drive into the Mac and launch Disk. Considering my Macbook Air neither has a CD drive nor do I possess a DVD, I preferred to create a live USB in Mac OS X. Create a Bootable Ubuntu USB Drive in Mac OS X. As I said earlier, creating a bootable USB in Mac OS X is a tricky procedure, be it for Ubuntu or any other bootable OS. A live CD (also live DVD, live disc, or live operating system) is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive.

A live CD (also live DVD, live disc, or live operating system) is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive. A Live CD allows users to run an operating system for any purpose without installing it or making any changes to the computer's configuration. Live CDs can run on a computer without secondary storage, such as a hard disk drive, or with a corrupted hard disk drive or file system, allowing data recovery.

As CD and DVD drives have been steadily phased-out, live CDs have become less popular, being replaced by live USBs, which are equivalent systems written onto USB flash drives, which have the added benefit of having writeable storage. The functionality of a live CD is also available with a bootable live USBflash drive, or an external hard disk drive connected by USB. Many live CDs offer the option of persistence by writing files to a hard drive or USB flash drive.

Many Linux distributions make ISO images available for burning to CD or DVD. While open source Operating Systems can be used for free, some commercial software, such as Windows To Go requires a license to use. Many Live CDs are used for data recovery, computer forensics, disk imaging, system recovery and malware removal. The Tails operating system is aimed at preserving privacy and anonymity of its users, allowing them to work with sensitive documents without leaving a record on a computer's hard drive.^[1][2]

History[edit]

All computers except the earliest digital computers are built with some form of minimal built-in loader, which loads a program or succession of programs from a storage medium, which then operate the computer. Initially a read-only medium such as punched tape or punched cards was used for initial program load. With the introduction of inexpensive read-write storage, read-write floppy disks and hard disks were used as boot media.

After the introduction of the audiocompact disc, it was adapted for use as a medium for storing and distributing large amounts of computer data. This data may also include application and operating-system software, sometimes packaged and archived in compressed formats. Later, it was seen to be convenient and useful to boot the computer directly from compact disc, often with a minimal working system to install a full system onto a hard drive. While there are read-write optical discs, either mass-produced read-only discs or write-once discs were used for this purpose.

The first Compact Disc drives on personal computers were generally much too slow to run complex operating systems; computers were not designed to boot from an optical disc. When operating systems came to be distributed on compact discs, either a boot floppy or the CD itself would boot specifically, and only, to install onto a hard drive. The world's first and oldest non-Linux live CD was the FM Towns OS first released in 1989, before the release of Macintosh System 7 in 1991 and Yggdrasil Linux in 1992.^{[citation needed]}

Linux[edit]

Although early developers and users of distributions built on top of the Linux kernel could take advantage of cheap optical disks and rapidly declining prices of CD drives for personal computers, the Linux distribution CDs or 'distros' were generally treated as a collection of installation packages that would first need to be permanently installed to hard disks on the target machine.

However, in the case of these distributions built on top of the Linux kernel, the free operating system was meeting resistance in the consumer market because of the perceived difficulty, effort, and risk involved in installing an additional partition on the hard disk, in parallel with an existing operating system installation.

The term 'live CD' was coined because, after typical PC RAM was large enough and 52x speed CD drives and CD burners were widespread among PC owners, it finally became convenient and practical to boot the kernel and run X11, a window manager and GUI applications directly from a CD without disturbing the OS on the hard disk.

This was a new and different situation for Linux than other operating systems, because the updates/upgrades were being released so quickly, different distributions and versions were being offered online, and especially because users were burning their own CDs.

The first Linux-based 'Live CD' was Yggdrasil Linux first released in beta form 1992~1993 (ceased production in 1995), though in practice its functionality was hampered due to the low throughput of contemporary CD-ROM drives. DemoLinux, released in 1998, was the first Linux distribution specially designed as a live CD. The Linuxcarebootable business card, first released in 1999, was the first Live CD to focus on system administration, and the first to be distributed in the bootable business card form factor. As of 2015, Finnix (first released in 2000) is the oldest Live CD still in production. Knoppix, a Debian-derived Linux distribution, was released in 2003, and found popularity as both a rescue disk system and as a primary distribution in its own right.

Since 2003, the popularity of live CDs has increased substantially, partly due to Linux Live scripts and remastersys, which made it very easy to build customized live systems. Most of the popular Linux distributions now include a live CD variant, which in some cases is also the preferred installation medium.

Uses[edit]

Live CDs are made for many different uses. Some are designed to demonstrate or 'test drive' a particular operating system (usually Linux or another free or open source operating system). Software can be tested, or run for a particular single use, without interfering with system setup. Data on a system which is not functioning normally due to operating system and software issues can be made available; for example, data can be recovered from a machine with an active virus infection without the virus process being active and causing more damage, and the virus can be removed with its defences against removal bypassed.

Although some live CDs can load into memory to free the optical drive for other uses, loading the data from a CD-ROM is still slower than a typical hard drive boot, so this is rarely the default with large live CD images, but for smaller live CD images loading the filesystem directly into RAM can provide a significant performance boost, as RAM is much faster than a hard drive, and uses less power.^[3] Experienced users of the operating system may also use a live CD to determine whether and to what extent a particular operating system or version is compatible with a particular hardware configuration and certain peripherals, or as a way to know beforehand which computer or peripheral will work before buying.^[3] A live CD can be used to troubleshoot hardware, especially when a hard drive fails, and more generally as a recovery disc in case of problems. Some live CDs can save user-created files in a Windows partition, a USB drive, a network drive, or other accessible media. Live backup CDs can create an image of drives, and back up files, without problems due to open files and inconsistent sets.

A few additional uses include:

• installing a Linux distribution to a hard drive
• Virus scanning and Malware removal^[4]
• system repair and restoration
• testing new versions of software
• listing & testing hardware^[5]
• Internet kiosks and public computers, which can be brought back to their original state by a reboot
• high security/non-invasive environment for a guest
• cracking, stealing, and changing passwords
• network security testing
• being the primary or backup operating system for any computer
• quick and simple clustering of computers^[6]
• playing video games or running applications that require a different operating system
• providing a secure server platform where crucial files cannot be permanently altered
• providing a secure, reliable platform for the performance of high-vulnerability tasks such as internet banking;
• Bypassing parental controls and other restrictions

Several live CDs are dedicated to specific type of applications according to the requirements of thematic user communities. These CDs are tailored to the needs of the applications in subject including general knowledge, tutorial, specifications and trial data too.

Some of these topics covers sub topics, e.g. IT administration breaks down to firewall, rescue, security, etc. type of live CDs. In some cases a particular Live DVD covers more than one topic.

Software appliances[edit]

Packaging a software appliance as an installable live CD, or live ISO, can often be beneficial as a single image can run on both real hardware and on most types of virtual machines.

This allows developers to avoid the complexities involved in supporting multiple incompatible virtual machine images formats andfocus on the lowest common denominator instead.

Typically after booting the machine from the live CD, the appliance either runs in non-persistent demo mode or installs itself, at the user's request, to an available storage device.

Mounting without burning[edit]

The files on a live CD ISO image can be accessed in Microsoft Windows with a disk image emulator such as Daemon Tools, or in Unix variants by mounting a loop device. Later versions of Windows (i.e. Windows 8 and later), and software available for earlier versions, allow an ISO to be mounted as a volume.

After mounting the live CD's filesystem, software on the live CD can be run directly, without booting it, by chrooting into the mounted filesystem.

A live CD ISO image can also be mounted by Virtual Machine software such as VirtualBox and VMware Workstation or can be converted to a Live USB using SYSLINUX. Special tools can automate this process.^[7]

Features[edit]

During live CD initialization, a user typically may resort to using one or more boot codes to change the booting behavior. These vary from distribution to distribution but can most often be accessed upon first boot screen by one of the function keys.

Some live CDs come with an installation utility launchable from a desktop icon that can optionally install the system on a hard drive or USB flash drive. Most live CDs can access the information on internal and/or external hard drives, diskettes and USB flash drives.

Live CDs are usually distributed on read-only media, requiring either copying to rewriteable media (i.e. a hard drive or CD writer) or complete remastering to install additional software; however, there are exceptions. If Puppy Linux is recorded to an open multisession medium, changes made during use (such as files created, programs installed, and preferences customised) are written in a new session to the boot medium^[8] persisting through subsequent boots.

The term 'Live CD' came to be used for any CD containing operating system and software which could be run without installation on the host computer. Operating systems which can be used live include AmigaOS 4, Amithlon, AROS, FreeBSD, FreeDOS, classic Mac OS, macOS, Microsoft Windows installation and repair discs, OS/2, ReactOS, NetBSD, OpenBSD, MINIX 3, Plan 9 from Bell Labs, MorphOS, OpenSolaris, BeleniX and others based on Solaris. There are maintenance versions of Microsoft Windows bootable from CD such as BartPE, Windows PE, and Microsoft Diagnostics and Recovery Toolset (DaRT), previously known as Emergency Repair Disk Commander (ERD Commander).

The first personal computer operating system on a CD to support 'live' operations might have been the AmigaOS, which could be booted from CD on an Amiga CDTV in 1990.^{[citation needed]}. Earlier examples of live OS are of course the operating systems used from floppy, and most widely spread is DOS.

Unlike previous operating systems on optical media, though, Linux and OS/2 'live CDs' were specifically designed to run without installation onto other media like a hard disk drive. The live CD concept was meant to promote Linux and showcase the abilities of the free, open source operating system on conventional personal computers with Microsoft Windows already installed.^{[citation needed]}

On a PC, a bootable Compact Disc generally conforms to the El Torito specification, introduced in 1994. Many Linux based live CDs use a compressed filesystem image, often with the cloop compressed loopback driver, or squashfs compressed filesystem, generally doubling effective storage capacity, although slowing application start up^{[citation needed]}.

The resulting environment can be quite rich: typical Knoppix systems include around 1,200 separate software packages. Live CDs have a reputation for supporting advanced auto-configuration and plug-and-play functionality. This came out of necessity to avoid requiring the user to configure the system each time it boots and to make it easily usable by those who are new to the operating system.

Creation[edit]

A read-only file system, such as on a CD-ROM has the drawback of being unable to save any current working data. For this reason, a read-only file system is often merged with a temporary writable file system in the form of a RAM disk. Often the default Linux directories '/home' (containing users' personal files and configuration files) and '/var' (containing variable data) are kept in ramdisk, because the system updates them frequently. Puppy Linux and some other live CDs allow a configuration and added files to be written and used in later sessions.

In modern live CDs, a read-only file system is merged with a RAM drive using transparent techniques such as UnionFS, AuFS or EWF. Boot loaders like syslinux can boot ISO files from USB memory devices.

Live CDs have to be able to detect and use a wide variety of hardware (including network cards, graphic cards etc.) in realtime, often using facilities such as udev, hotplug, hal, udisk etc.. which are a common part of all distributions based on Linux kernel 2.6.

See also[edit]

References[edit]

1. ^Timm, Trevor (2 April 2014). 'Help Support the Little-Known Privacy Tool That Has Been Critical to Journalists Reporting on the NSA'. Freedom of the Press Foundation. Retrieved 18 April 2014.
2. ^Finley, Klint (14 April 2014). 'Out in the Open: Inside the Operating System Edward Snowden Used to Evade the NSA'. WIRED. Retrieved 18 April 2014.
3. ^ ^abBrickner, David (2005). Test Driving Linux: From Windows to Linux in 60 Seconds. O'Reilly. ISBN0-596-00754-X.
4. ^'Scan a Windows PC for Viruses from a Ubuntu Live CD'. howtogeek.com. Retrieved 19 March 2018.
5. ^'Home - HDT Project'. HDT Project. Archived from the original on 25 July 2018. Retrieved 19 March 2018.
6. ^'FlashMob Computing – FlashMob Computing'. flashmobcomputing.org. Retrieved 19 March 2018.
7. ^'USB Installation Media - UNetbootin'. community.ubuntu.com. Ubuntu Community. Retrieved 11 February 2014.
8. ^'How to Create a Multi-session LiveDVD'. Puppy Linux. 26 April 2011. Retrieved 1 August 2018.

External links[edit]

• Pondering Live CDs - A BSD perspective on the concept of Live CDs

A live USB is a USB flash drive or external hard disk drive containing a full operating system that can be booted. They are the evolutionary next step after live CDs, but with the added benefit of writable storage, allowing customizations to the booted operating system. Live USBs can be used in embedded systems for system administration, data recovery, or test driving, and can persistently save settings and install software packages on the USB device.

Many operating systems including Mac OS 9, macOS, Windows XP Embedded and a large portion of Linux and BSD distributions can run from a USB flash drive, and Windows 8 Enterprise has a feature titled Windows To Go for a similar purpose.

Background[edit]

To repair a computer with booting issues, technicians often use lightweight operating systems on bootable media and a command-line interface. The development of the first live CDs with graphical user interface made it feasible for non-technicians to repair malfunctioning computers. Most Live CDs are Linux-based, and in addition to repairing computers, these would occasionally be used in their own right as operating systems.

Personal computers introduced USB booting in the early 2000s, with the Macintosh computers introducing the functionality in 1999 beginning with the Power Mac G4 with AGP graphics and the slot-loading iMac G3 models.^[1] Intel-based Macs carried this functionality over with booting macOS from USB.^[2] Specialized USB-based booting was proposed by IBM in 2004 with Reincarnating PCs with Portable SoulPads and Boot GNU/Linux from a FireWire device.^[3][4]

Benefits and limitations[edit]

Live USBs share many of the benefits and limitations of live CDs, and also incorporate their own.

Benefits[edit]

• In contrast to live CDs, the data contained on the booting device can be changed and additional data stored on the same device. A user can carry their preferred operating system, applications, configuration, and personal files with them, making it easy to share a single system between multiple users.
• Live USBs provide the additional benefit of enhanced privacy because users can easily carry the USB device with them or store it in a secure location (e.g. a safe), reducing the opportunities for others to access their data. On the other hand, a USB device is easily lost or stolen, so data encryption and backup is even more important than with a typical desktop system.
• The absence of moving parts in USB flash devices allows true random access, thereby avoiding the rotational latency and seek time of hard drives or optical media, meaning small programs will start faster from a USB flash drive than from a local hard disk or live CD. However, as USB devices typically achieve lower data transfer rates than internal hard drives, booting from older computers that lack support for USB 2.0 or newer can be very slow.

Limitations[edit]

• LiveUSB OSes like Ubuntu Linux apply all filesystem writes to a casper filesystem overlay (casper-rw) that, once full or out of flash drive space, becomes unusable and the OS ceases to boot.
• USB controllers on add-in cards (e.g. ISA, PCI, and PCI-E) are almost never capable of being booted from, so systems that do not have native USB controllers in their chipset (e.g. such as older ones before USB) likely will be unable to boot from USB even when USB is enabled via such an add-in card.
• Some computers, particularly older ones, may not have a BIOS that supports USB booting. Many which do support USB booting may still be unable to boot the device in question. In these cases a computer can often be 'redirected' to boot from a USB device through use of an initial bootable CD or floppy disk.^[5][6][7]
• Some Intel-based Macintosh computers have limitations when booting from USB devices – while the Extensible Firmware Interface (EFI) firmware can recognize and boot from USB drives, it can do this only in EFI mode. When the firmware switches to 'legacy' BIOS mode, it no longer recognizes USB drives. Non-Macintosh systems, notably Windows and Linux, may not be typically booted in EFI mode and thus USB booting may be limited to supported hardware and software combinations that can easily be booted via EFI.^[8] However, programs like Mac Linux USB Loader can alleviate the difficulties of the task of booting a Linux-live USB on a Mac. This limitation could be fixed by either changing the Apple firmware to include a USB driver in BIOS mode, or changing the operating systems to remove the dependency on the BIOS.
• Due to the additional write cycles that occur on a full-blown installation, the life of the flash drive may be slightly reduced. This doesn't apply to systems particularly designed for live systems which keep all changes in RAM until the user logs off.^[9] A write-locked SD card (known as a Live SD, the solid-state counterpart to a live CD) in a USB flash card reader adapter is an effective way to avoid any duty cycles on the flash medium from writes and circumvent this problem. The SD card as a WORM device has an essentially unlimited life. An OS such as Linux can then run from the live USB/SD card and use conventional media for writing, such as magnetic disks, to preserve system changes; .

Setup[edit]

Various applications exist to create live USBs; examples include Rufus, Fedora Live USB Creator, UNetbootin, WinToUSB, Win32DiskImager, and YUMI, which works with a variety of distributions. A few Linux distributions and live CDs have ready-made scripts which perform the steps below automatically. In addition, on Knoppix and Ubuntu extra applications can be installed, and a persistentfile system can be used to store changes. A base install ranges between as little as 16 MiB (Tiny Core Linux) to a large DVD-sized install (4 gigabytes).

To set up a live USB system for commodity PC hardware, the following steps must be taken:

• A USB flash drive needs to be connected to the system, and be detected by it
• One or more partitions may need to be created on the USB flash drive
• The 'bootable' flag must be set on the primary partition on the USB flash drive
• An MBR must be written to the primary partition of the USB flash drive
• The partition must be formatted (most often in FAT32 format, but other file systems can be used too)
• A bootloader must be installed to the partition (most often using syslinux when installing a Linux system)
• A bootloader configuration file (if used) must be written
• The necessary files of the operating system and default applications must be copied to the USB flash drive
• Language and keyboard files (if used) must be written to the USB flash drive
• USB support in the BIOS’s boot menu (although there are ways to get around this; actual use of a CD or DVD can allow the user to choose if the medium can later be written to. Write Once Read Many discs allow certainty that the live system will be clean the next time it is rebooted.)

Knoppix live CDs have a utility that, on boot, allows users to declare their intent to write the operating system's file structures either temporarily, to a RAM disk, or permanently, on disk or flash media to preserve any added configurations and security updates. This can be easier than recreating the USB system but may be moot since many live USB tools are simple to use.

Full installation[edit]

An alternative to a live solution is a traditional operating system installation with the elimination of swap partitions. This installation has the advantage of being efficient for the software, as a live installation would still contain software removed from the persistent file due to the operating system’s installer still being included with the media. However, a full installation is not without disadvantages; due to the additional write cycles that occur on a full installation, the life of the flash drive may be slightly reduced. To mitigate this, some live systems are designed to store changes in RAM until the user powers down the system, which then writes such changes. Another factor is if the speed of the storage device is poor; performance can be comparable to legacy computers even on machines with modern parts if the flash drive transfers such speeds. One way to solve this is to use a USB hard drive, as they generally give better performance than flash drives regardless of the connector.

Microsoft Windows[edit]

Although many live USBs rely on booting an open-source operating system such as Linux, it is possible to create live USBs for Microsoft Windows by using Diskpart^{[citation needed]} or WinToUSB.^[10]

See also[edit]

References[edit]

1. ^'USB Info and Benefits of Dual-Channel USB'. Apple (published February 20, 2012). September 16, 2003. Archived from the original on May 12, 2013. Retrieved September 25, 2016. Bootable USB drives: A storage device such as a SuperDisk, Zip disk, or other USB storage drive can be used to hold a valid system folder and used at startup.
2. ^'Starting from an external USB storage device (Intel-based Macs)'. Apple. March 22, 2016. Archived from the original on May 22, 2016. Retrieved September 25, 2016.
3. ^Singer, Michael (August 15, 2005). 'IBM brains capture a PC's soul'. CNET. CBS Interactive. Archived from the original on September 27, 2016. Retrieved September 25, 2016.
4. ^Honeyford, Martyn (July 15, 2004). 'Boot Linux from a FireWire device'. IBM DeveloperWorks. IBM. Archived from the original on January 17, 2007. Retrieved May 15, 2016.
5. ^Trevor (May 6, 2010). 'Boot from a USB Drive Even If Your BIOS Won't Let You'. How-To Geek. Archived from the original on September 23, 2016. Retrieved September 25, 2016.
6. ^'Plop Boot Manager'. February 7, 2012. Retrieved September 25, 2016.
7. ^'Use a Floppy to Boot USB Pendrive Linux'. Pen Drive Linux. 2007-11-21. Retrieved September 25, 2016.
8. ^knome (December 14, 2013). 'MactelSupportTeam/EFI-Boot-Mactel'. Ubuntu Community Help Wiki. Canonical Ltd. Archived from the original on March 4, 2016. Retrieved September 25, 2016.
9. ^'XFCE minimum install HD'. Linux Mint Forums. Archived from the original on September 27, 2016. Retrieved September 25, 2016. Live cd only write to the swap partition if your pc has one.
   If it doesn't it'll only use your RAM.
10. ^Gordon, Whitson. 'How to Run a Portable Version of Windows from a USB Drive'. Lifehacker. Gawker Media. Archived from the original on September 25, 2016. Retrieved September 25, 2016.

External links[edit]

Live Usb Creator Mac Os

Live Usb Mac Os 10.13