Safe mode is a
diagnostic modeDiagnosis is the identification of the nature of anything, either by process of elimination or other analytical methods...
of a computer
operating systemAn operating system is an interface between hardware and user which is responsible for the management and coordination of activities and the sharing of the resources of the computer that acts as a host for computing applications run on the machine. As a host, one of the purposes of an operating...
(OS). It can also refer to a mode of operation by
application softwareApplication software is a computer program that functions and is operated by means of a computer, with the purpose of supporting or improving the software user's work. In other words, it is the subclass of computer software that employs the capabilities of a computer directly and thoroughly to a...
.
Safe mode is intended to fix most, if not all problems within an operating system.
Microsoft WindowsMicrosoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces...
and
Mac OS XMac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems...
are examples of contemporary operating systems that implement a safe mode; as well as other complex
electronic devicesElectronics is a branch of science and technology that deals with the controlled flow of electrons. The ability to control electron flow is usually applied to information handling or device control. Electronics is distinct from electrical science and technology, which deals with the generation,...
.
An
operating systemAn operating system is an interface between hardware and user which is responsible for the management and coordination of activities and the sharing of the resources of the computer that acts as a host for computing applications run on the machine. As a host, one of the purposes of an operating...
in safe mode will have reduced functionality, but the task of isolating problems is easier because many non-core components are disabled (turned off).
Safe mode is a
diagnostic modeDiagnosis is the identification of the nature of anything, either by process of elimination or other analytical methods...
of a computer
operating systemAn operating system is an interface between hardware and user which is responsible for the management and coordination of activities and the sharing of the resources of the computer that acts as a host for computing applications run on the machine. As a host, one of the purposes of an operating...
(OS). It can also refer to a mode of operation by
application softwareApplication software is a computer program that functions and is operated by means of a computer, with the purpose of supporting or improving the software user's work. In other words, it is the subclass of computer software that employs the capabilities of a computer directly and thoroughly to a...
.
Safe mode is intended to fix most, if not all problems within an operating system.
Operating system safe mode
Microsoft WindowsMicrosoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces...
and
Mac OS XMac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems...
are examples of contemporary operating systems that implement a safe mode; as well as other complex
electronic devicesElectronics is a branch of science and technology that deals with the controlled flow of electrons. The ability to control electron flow is usually applied to information handling or device control. Electronics is distinct from electrical science and technology, which deals with the generation,...
.
An
operating systemAn operating system is an interface between hardware and user which is responsible for the management and coordination of activities and the sharing of the resources of the computer that acts as a host for computing applications run on the machine. As a host, one of the purposes of an operating...
in safe mode will have reduced functionality, but the task of isolating problems is easier because many non-core components are disabled (turned off). An installation that will only
bootIn computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. A boot sequence is the initial set of operations that the computer performs when power is switched on...
into its 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, typically safe mode loads as few executable modules as possible and usually disables devices, except for the minimum necessary to display information and accept input. Safe mode 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 ConsoleThe Recovery Console is a feature of the Windows 2000, Windows XP and Windows Server 2003 operating systems. It provides the means for administrators to perform a limited range of tasks using a command line interface...
, a small text-based troubleshooting mode kept separate from the main operating system (and can also be accessed by booting the install CD), or to various "safe mode" options that run the dysfunctional operating system, 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 provides minimal access to features.
Microsoft Windows' safe mode is accessed by pressing the
F8 keyA function key is a key on a computer or terminal keyboard which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions...
as the operating system boots. 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.
An equivalently minimal setting in
Unix-likeA Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating systems is
single-user modeThe term runlevel refers to a mode of operation in one of the computer operating systems that implement Unix System V-style initialization. Conventionally, seven runlevels exist, numbered from zero to six; though up to ten, from zero to nine, may be used. S is sometimes used as a synonym for one...
, in which
daemonsIn Unix and other computer multitasking operating systems, a daemon is a computer program that runs in the background, rather than under the direct control of a user; they are usually initiated as background processes...
and the
X Window SystemThe X Window System is a computer software system and network protocol that provides a graphical user interface for networked computers, and was initially developed as part of Project Athena...
are not started, and only the root user can log in. On
Mac OSMac OS is the trademarked name for a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
versions 6, 7, 8 and 9, a similar mode is achieved by holding down the
shift keyThe shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
while booting, which starts the system without
extensionsOn the Apple Macintosh operating system prior to Mac OS X, extensions were small pieces of code that extended the system's functionality. They were run initially at start-up time, and operated by a variety of mechanisms, including trap patching and other code modifying techniques. Initially an...
. In
Mac OS XMac OS X is a line of computer operating systems developed, marketed, and sold by Apple Inc., and since 2002 has been included with all new Macintosh computer systems...
holding the shift key after powering up puts the system in safe mode. Safe mode with
networkingComputer networking is the engineering discipline concerned with communication between computer systems or devices. Networking, routers, routing protocols, and networking over the public Internet have their specifications defined in documents called RFCs...
, one of the variations of safe mode, can be used to troubleshoot network issues.
Application software safe mode
Application softwareApplication software is a computer program that functions and is operated by means of a computer, with the purpose of supporting or improving the software user's work. In other words, it is the subclass of computer software that employs the capabilities of a computer directly and thoroughly to a...
sometimes offers a safe mode as well. In the
PHPPHP, or PHP: Hypertext Preprocessor, is a widely used, general-purpose scripting language that was originally designed for web development, to produce dynamic web pages. It can be embedded into HTML and generally runs on a web server, which needs to be configured to process PHP code and create web...
interpreterIn computer science, an interpreter is a computer program which reads source code written in a high-level programming language, transforms the code to machine code, and executes the machine code. Using an interpreter, a single source file can produce equal results even in vastly different systems...
, prior to version 6, safe mode offers stricter security measures.
Mozilla FirefoxMozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. Firefox has 23.75% of the recorded usage share of web browsers , making it the second most popular browser in terms of current use worldwide after Microsoft's...
's safe mode allows the user to remove extensions which may be preventing the browser from loading.
Internet ExplorerWindows Internet Explorer , is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems starting in 1995...
can run in "No Add-Ons" mode and Protected Mode.
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