Temporary file
Encyclopedia
Temporary files may be created by computer program
s for a variety of purposes; principally when a program cannot allocate enough memory for its tasks, when the program is working on data bigger than the architecture's address space
, or as a primitive form of inter-process communication
.
s employ virtual memory
, however programs that use large amounts of data (e.g. video editing
) may need to create temporary files.
, sockets
or shared memory
to pass data among programs, but often the simplest way (especially for programs that follow the Unix philosophy
) is to write data into a temporary file and inform the receiving program of the location of the temporary file.
for temporary files is "
On POSIX
systems, temporary files can be safely created with the or library functions, or with the program. These files are typically located in the standard temporary directory, /tmp on Unix machines or %TEMP% (which is log-in specific) on Windows machines.
Usually a temporary file is deleted automatically when the program exits or the file is closed. To generate a temporary file name that will survive past the lifespan of the creating program, or
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...
s for a variety of purposes; principally when a program cannot allocate enough memory for its tasks, when the program is working on data bigger than the architecture's address space
Address space
In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral device, disk sector, a memory cell or other logical or physical entity.- Overview :...
, or as a primitive form of inter-process communication
Inter-process communication
In computing, Inter-process communication is a set of methods for the exchange of data among multiple threads in one or more processes. Processes may be running on one or more computers connected by a network. IPC methods are divided into methods for message passing, synchronization, shared...
.
Auxiliary memory
Modern operating systemOperating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s employ virtual memory
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
, however programs that use large amounts of data (e.g. video editing
Video editing software
Video editing software, is application software which handles the post-production video editing of digital video sequences on a computer non-linear editing systems...
) may need to create temporary files.
Inter-process communication
Most operating systems offer primitives such as pipesPipeline (software)
In software engineering, a pipeline consists of a chain of processing elements , arranged so that the output of each element is the input of the next. Usually some amount of buffering is provided between consecutive elements...
, sockets
Internet socket
In computer networking, an Internet socket or network socket is an endpoint of a bidirectional inter-process communication flow across an Internet Protocol-based computer network, such as the Internet....
or shared memory
Shared memory
In computing, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Depending on context, programs may run on a single processor or on multiple separate processors...
to pass data among programs, but often the simplest way (especially for programs that follow the Unix philosophy
Unix philosophy
The Unix philosophy is a set of cultural norms and philosophical approaches to developing software based on the experience of leading developers of the Unix operating system.-McIlroy: A Quarter Century of Unix:...
) is to write data into a temporary file and inform the receiving program of the location of the temporary file.
Cleanup
Some programs create temporary files and then leave them behind - they do not delete them. This can happen because the program crashed or the developer of the program simply forgot to add the code needed to delete the temporary files after the program is done with them (disk leak). In Microsoft Windows the temporary files left behind by the programs accumulate over time and can take up a lot of disk space. System utilities, called temporary file cleaners or disk cleaners, can be used to address this issue. Personal workstations with UNIX-based operating systems do not suffer from the same problem because their temporary files are wiped at boot. Servers, however, are affected because they are rarely rebooted.Usage
The usual filename extensionFilename extension
A filename extension is a suffix to the name of a computer file applied to indicate the encoding of its contents or usage....
for temporary files is "
.TMP". Temporary files are normally created in a designated temporary directory reserved for the creation of temporary files.On POSIX
POSIX
POSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
systems, temporary files can be safely created with the or library functions, or with the program. These files are typically located in the standard temporary directory, /tmp on Unix machines or %TEMP% (which is log-in specific) on Windows machines.
Usually a temporary file is deleted automatically when the program exits or the file is closed. To generate a temporary file name that will survive past the lifespan of the creating program, or
GetTempFileName(...) (Windows only) can be used.See also
- Temporary folderTemporary folderIn computing, a temporary folder or temporary directory is a directory used to hold temporary files. Many operating systems and some software automatically delete the contents of this directory at bootup or at regular intervals....
- Temporary filesystem
- Temporary variableTemporary variableIn computer programming, a temporary variable is a variable whose purpose is short-lived, usually to hold temporary data that will soon be discarded, or before it can be placed at a more permanent memory location. Because it is short-lived, it is usually declared with local scope...