Safe mode is a diagnostic mode of a computer operating system (OS). It can also refer to a mode of operation by application software. Safe mode is intended to help fix most, if not all, problems within an operating system. It is also widely used for removing rogue security software.
Microsoft Windows, macOS, Android and Linux distributions such as Ubuntu and Linux Mint are examples of contemporary operating systems that implement a safe mode (called "Safe Boot" in macOS) as well as other complex electronic devices.
In safe mode, an operating system has reduced functionality, but the task of isolating problems is easier since many non-core components are disabled, such as sound. An installation that will only boot into safe mode typically has a major problem, such as disk corruption or the installation of poorly-configured software that prevents the operating system from successfully booting into its normal operating mode.
Though it varies by operating system, safe mode typically loads only essential executable modules and disables devices except for those necessary to display information and accept input. It can also take the form of a parallel "miniature" operating system that has no configuration information shared with the normal operating system. For example, on Microsoft Windows, the user can also choose to boot to the Recovery Console, a small text-based troubleshooting mode kept separate from the main operating system (which can also be accessed by booting the install CD) or to various "safe mode" options that run the dysfunctional OS but with features, such as video drivers, audio, and networking, disabled.
Safe mode typically provides access to utility and diagnostic programs so a user can troubleshoot what is preventing the operating system from working normally. Safe mode is intended for maintenance, not functionality, and it provides minimal access to features.
Microsoft Windows' safe mode (for 7/Vista [1] /XP [2] /2000/ME/98/95 [ citation needed ]) is accessed by pressing the F8 key as the operating system boots. [3] Also, in a multi-boot environment with multiple versions of Windows installed side by side, the F8 key can be pressed at the OS selector prompt to get to safe mode. However, under Windows 8 (released in 2012), the traditional press-F8-for-safe-mode-options UI convention no longer works, and either Shift-F8 or a special GUI-based workaround is necessary. [4]
An equivalently minimal setting in Unix-like operating systems is single-user mode, in which daemons and the X Window System are not started, and only the root user can log in. It can do emergency repairs or maintenance, including resetting users' passwords on the machine without the need to know the old one. [5]
In macOS holding the shift key after powering up activates Safe Boot that has background maintenance features (Besides the mode selection, it runs a file system repair, and in Mac OS 10.4, it disables all fonts other than those in /System/Library/Fonts, moves to the Trash all font caches normally stored in /Library/Caches/com.apple.ATS/(uid)/, where (uid) is a user ID number such as 501, and disables all startup items and any Login Items). Unlike in Windows where safe mode with networking is disabled by default and requires using a safe mode with networking enabled, in the macOS Safe Boot always includes networking.
On the Classic Mac OS versions 6, 7, 8, and 9, a similar mode to the Unix root is achieved by holding down the shift key while booting, which starts the system without extensions.
iOS does not have a safe mode, however some jailbreaks add a safe mode where all tweaks are disabled, the wallpaper is black and a notification will tell you that you are in safe mode. In that mode, some apps may not launch.
The way that safe mode in Android can be activated differs per vendor. [6] Safe mode can be disabled by rebooting the device. [7]
When you reboot into safe mode in Android, downloaded apps and widgets are automatically disabled, but built-in apps remain available. A watermark in the bottom-left corner also appears if you're booted to either normal or safe mode.
Some devices also turn their radios off automatically upon booting into safe mode.
Application software sometimes offers a safe mode as well. In the PHP interpreter, prior to version 5.4, safe mode offers stricter security measures. [8] The Glasgow Haskell Compiler from version 7.2 offers "Safe Haskell" mode, restricting usage of functions such as unsafePerformIO
. Mozilla Firefox's safe mode allows the user to remove extensions which may be preventing the browser from loading. Internet Explorer can run in "No Add-Ons" mode and Protected Mode. Cydia's MobileSubstrate also has a safe mode that allows the user to uninstall tweaks and extensions that may crash the SpringBoard.
A Linux distribution is an operating system made from a software collection that includes the Linux kernel and often a package management system. Linux users usually obtain their operating system by downloading one of the Linux distributions, which are available for a wide variety of systems ranging from embedded devices and personal computers to powerful supercomputers.
Microsoft Windows is a product line of proprietary graphical operating systems developed and marketed by Microsoft. It is grouped into families and sub-families that cater to particular sectors of the computing industry – Windows (unqualified) for a consumer or corporate workstation, Windows Server for a server and Windows IoT for an embedded system. Defunct families include Windows 9x, Windows Mobile, Windows Phone, and Windows Embedded Compact.
In computing, cross-platform software is computer software that is designed to work in several computing platforms. Some cross-platform software requires a separate build for each platform, but some can be directly run on any platform without special preparation, being written in an interpreted language or compiled to portable bytecode for which the interpreters or run-time packages are common or standard components of all supported platforms.
In computing, the superuser is a special user account used for system administration. Depending on the operating system (OS), the actual name of this account might be root, administrator, admin or supervisor. In some cases, the actual name of the account is not the determining factor; on Unix-like systems, for example, the user with a user identifier (UID) of zero is the superuser, regardless of the name of that account; and in systems which implement a role-based security model, any user with the role of superuser can carry out all actions of the superuser account. The principle of least privilege recommends that most users and applications run under an ordinary account to perform their work, as a superuser account is capable of making unrestricted, potentially adverse, system-wide changes.
NTLDR is the boot loader for all releases of Windows NT operating system from 1993 with the release of Windows NT 3.1 up until Windows XP and Windows Server 2003. From Windows Vista onwards it was replaced by the BOOTMGR bootloader. NTLDR is typically run from the primary storage device, but it can also run from portable storage devices such as a CD-ROM, USB flash drive, or floppy disk. NTLDR can also load a non NT-based operating system given the appropriate boot sector in a file.
Multi-booting is the act of installing multiple operating systems on a single computer, and being able to choose which one to boot. The term dual-booting refers to the common configuration of specifically two operating systems. Multi-booting may require a custom boot loader.
The Advanced Host Controller Interface (AHCI) is a technical standard defined by Intel that specifies the register-level interface of Serial ATA (SATA) host controllers in a non-implementation-specific manner in its motherboard chipsets.
The GUID Partition Table (GPT) is a standard for the layout of partition tables of a physical computer storage device, such as a hard disk drive or solid-state drive, using universally unique identifiers (UUIDs), which are also known as globally unique identifiers (GUIDs). Forming a part of the Unified Extensible Firmware Interface (UEFI) standard, it is nevertheless also used for some BIOSs, because of the limitations of master boot record (MBR) partition tables, which use 32 bits for logical block addressing (LBA) of traditional 512-byte disk sectors.
Hibernation in computing is powering down a computer while retaining its state. When hibernation begins, the computer saves the contents of its random access memory (RAM) to a hard disk or other non-volatile storage. When the computer is turned on the RAM is restored and the computer is exactly as it was before entering hibernation. Hibernation was first implemented in 1992 and patented by Compaq Computer Corporation in Houston, Texas.
In computer security, executable-space protection marks memory regions as non-executable, such that an attempt to execute machine code in these regions will cause an exception. It makes use of hardware features such as the NX bit, or in some cases software emulation of those features. However, technologies that emulate or supply an NX bit will usually impose a measurable overhead while using a hardware-supplied NX bit imposes no measurable overhead.
Kiosk software is the system and user interface software designed for an interactive kiosk or Internet kiosk enclosing the system in a way that prevents user interaction and activities on the device outside the scope of execution of the software. This way, the system replaces the look and feel of the system it runs over, allowing for customization and limited offering of ad-hoc services. KioskTotal Kiosk software locks down the application in order to protect the kiosk from users which is specially relevant under, but not only limited to, scenarios where the device is publicly accessed such libraries, vending machines or public transport. Kiosk software may offer remote monitoring to manage multiple kiosks from another location. An Email or text alert may be automatically sent from the kiosk for daily activity reports or generated in response to problems detected by the software. Other features allow for remote updates of the kiosk's content and the ability to upload data such as kiosk usage statistics. Kiosk software is used to manage a touchscreen, allowing users to touch the monitor screen to make selections. A virtual keyboard eliminates the need for a computer keyboard. Kiosk software enables digital signage devices to operate in a dedicated mode, ensuring that the devices run for a specified purpose, thus providing additional security compared to normal mode use.
A live USB is a portable USB-attached external data storage device containing a full operating system that can be booted from. The term is reminiscent of USB flash drives but may encompass an external hard disk drive or solid-state drive, though they may be referred to as "live HDD" and "live SSD" respectively. 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.
Resolution independence is where elements on a computer screen are rendered at sizes independent from the pixel grid, resulting in a graphical user interface that is displayed at a consistent physical size, regardless of the resolution of the screen.
Operating system Wi-Fi support is defined as the facilities an operating system may include for Wi-Fi networking. It usually consists of two pieces of software; device drivers; and applications for configuration and management.
ChromeOS, sometimes styled as chromeOS and formerly styled as Chrome OS, is a Linux distribution developed and designed by Google. It is derived from the open-source ChromiumOS, based on the Linux kernel, and uses the Google Chrome web browser as its principal user interface.
The hacking of consumer electronics is a common practice that users perform to customize and modify their devices beyond what is typically possible. This activity has a long history, dating from the days of early computer, programming, and electronics hobbyists.
The Android Debug Bridge is a programming tool used for the debugging of Android-based devices. The daemon on the Android device connects with the server on the host PC over USB or TCP, which connects to the client that is used by the end-user over TCP. Made available as open-source software under the Apache License by Google since 2007, its features include a shell and the possibility to make backups. The adb software is available for Windows, Linux and macOS. It has been misused by botnets and other malware, for which mitigations were developed such as RSA authentication and device whitelisting.
Comparison of user features of operating systems refers to a comparison of the general user features of major operating systems in a narrative format. It does not encompass a full exhaustive comparison or description of all technical details of all operating systems. It is a comparison of basic roles and the most prominent features. It also includes the most important features of the operating system's origins, historical development, and role.
Bootloader unlocking is the process of disabling the bootloader security that makes secure boot possible. It can make advanced customizations possible, such as installing a custom firmware. On smartphones this can be a custom Android distribution or another mobile operating system. Some bootloaders are not locked at all, others can be unlocked using a standard command, others need assistance from the manufacturer. Some do not include an unlocking method and can only be unlocked through a software exploit.