Safe mode is adiagnostic mode of a computeroperating system (OS). It can also refer to a mode of operation byapplication 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 andLinux distributions such asUbuntu andLinux Mint are examples of contemporary operating systems that implement a safe mode as well as other complexelectronic 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 onlyboot 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 disablesdevices 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 theRecovery 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 cantroubleshoot 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 (for7/Vista[1] /XP[2] /2000/ME/98/95[citation needed][3]) is accessed by pressing theF8 key as the operating system boots.[4] 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.[5]
An equivalently minimal setting inUnix-like operating systems issingle-user mode, in whichdaemons and theX Window System are not started, and only theroot user canlog in. It can do emergency repairs or maintenance, including resetting users' passwords on the machine without the need to know the old one.[6]
In addition to single-user mode, macOS also supports safe mode; holding the shift key after powering up activates Safe Boot,[7] which has background maintenance features (Besides the mode selection, it runs a file system repair, and in Mac OS X 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 withnetworking is disabled by default and requires using a safe mode with networking enabled, in the macOS Safe Boot always includes networking.
On theClassic Mac OS versions 6, 7, 8, and 9, a similar mode to Safe Mode is achieved by holding down theshift key while booting, which starts the system withoutextensions.
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iOS does not have a safe mode,[8] however somejailbreaks add a safe mode where all tweaks are disabled,[9] the wallpaper is black, and a notification will tell you that you are in safe mode. In that mode, some apps may not launch.[10]
The way that safe mode in Android can be activated differs per vendor.[11] Safe mode can be disabled by rebooting the device.[12]
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 thePHPinterpreter, prior to version 5.4, safe mode offers stricter security measures.[13] TheGlasgow Haskell Compiler from version 7.2 offers "Safe Haskell" mode, restricting usage of functions such asunsafePerformIO.Mozilla Firefox's safe mode allows the user to removeextensions which may be preventing the browser from loading.Internet Explorer can run in "No Add-Ons" mode and Protected Mode.Cydia's Mobile Substrate also has a safe mode that allows the user to uninstalltweaks and extensions that may crash theSpringboard.Minecraft has a safe mode that activates if a player attempts to open a world with an invalid data pack, which gives the option to load the world using only the vanilla data pack.