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Tmp

A simple temporary file and directory creator for node.js.

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About

This is a widely used library to create temporary files and directories in a node.js environment.

Tmp offers both an asynchronous and a synchronous API. For all API calls, all the parameters are optional. There also exists a promisified version of the API, see tmp-promise.

Tmp uses crypto for determining random file names, or, when using templates, a six letter random identifier. And just in case that you do not have that much entropy left on your system, Tmp will fall back to pseudo random numbers.

You can set whether you want to remove the temporary file on process exit or not.

If you do not want to store your temporary directories and files in the standard OS temporary directory, then you are free to override that as well.

An Important Note on Compatibility

See the CHANGELOG for more information.

Version 0.1.0

Since version 0.1.0, all support for node versions < 0.10.0 has been dropped.

Most importantly, any support for earlier versions of node-tmp was also dropped.

If you still require node versions < 0.10.0, then you must limit your node-tmp dependency to versions below 0.1.0.

Version 0.0.33

Since version 0.0.33, all support for node versions < 0.8 has been dropped.

If you still require node version 0.8, then you must limit your node-tmp dependency to version 0.0.33.

For node versions < 0.8 you must limit your node-tmp dependency to versions < 0.0.33.

How to install

npm install tmp

Usage

Please also check API docs.

Asynchronous file creation

Simple temporary file creation, the file will be closed and unlinked on process exit.

const tmp = require('tmp');

tmp.file(function _tempFileCreated(err, path, fd, cleanupCallback) {
  if (err) throw err;

  console.log('File: ', path);
  console.log('Filedescriptor: ', fd);
  
  // If we don't need the file anymore we could manually call the cleanupCallback
  // But that is not necessary if we didn't pass the keep option because the library
  // will clean after itself.
  cleanupCallback();
});

Synchronous file creation

A synchronous version of the above.

const tmp = require('tmp');

const tmpobj = tmp.fileSync();
console.log('File: ', tmpobj.name);
console.log('Filedescriptor: ', tmpobj.fd);
  
// If we don't need the file anymore we could manually call the removeCallback
// But that is not necessary if we didn't pass the keep option because the library
// will clean after itself.
tmpobj.removeCallback();

Note that this might throw an exception if either the maximum limit of retries for creating a temporary name fails, or, in case that you do not have the permission to write to the directory where the temporary file should be created in.

Asynchronous directory creation

Simple temporary directory creation, it will be removed on process exit.

If the directory still contains items on process exit, then it won't be removed.

const tmp = require('tmp');

tmp.dir(function _tempDirCreated(err, path, cleanupCallback) {
  if (err) throw err;

  console.log('Dir: ', path);
  
  // Manual cleanup
  cleanupCallback();
});

If you want to cleanup the directory even when there are entries in it, then you can pass the unsafeCleanup option when creating it.

Synchronous directory creation

A synchronous version of the above.

const tmp = require('tmp');

const tmpobj = tmp.dirSync();
console.log('Dir: ', tmpobj.name);
// Manual cleanup
tmpobj.removeCallback();

Note that this might throw an exception if either the maximum limit of retries for creating a temporary name fails, or, in case that you do not have the permission to write to the directory where the temporary directory should be created in.

Asynchronous filename generation

It is possible with this library to generate a unique filename in the specified directory.

const tmp = require('tmp');

tmp.tmpName(function _tempNameGenerated(err, path) {
    if (err) throw err;

    console.log('Created temporary filename: ', path);
});

Synchronous filename generation

A synchronous version of the above.

const tmp = require('tmp');

const name = tmp.tmpNameSync();
console.log('Created temporary filename: ', name);

Advanced usage

Asynchronous file creation

Creates a file with mode 0644, prefix will be prefix- and postfix will be .txt.

const tmp = require('tmp');

tmp.file({ mode: 0o644, prefix: 'prefix-', postfix: '.txt' }, function _tempFileCreated(err, path, fd) {
  if (err) throw err;

  console.log('File: ', path);
  console.log('Filedescriptor: ', fd);
});

Synchronous file creation

A synchronous version of the above.

const tmp = require('tmp');

const tmpobj = tmp.fileSync({ mode: 0o644, prefix: 'prefix-', postfix: '.txt' });
console.log('File: ', tmpobj.name);
console.log('Filedescriptor: ', tmpobj.fd);

Controlling the Descriptor

As a side effect of creating a unique file tmp gets a file descriptor that is returned to the user as the fd parameter. The descriptor may be used by the application and is closed when the removeCallback is invoked.

In some use cases the application does not need the descriptor, needs to close it without removing the file, or needs to remove the file without closing the descriptor. Two options control how the descriptor is managed:

  • discardDescriptor - if true causes tmp to close the descriptor after the file is created. In this case the fd parameter is undefined.
  • detachDescriptor - if true causes tmp to return the descriptor in the fd parameter, but it is the application's responsibility to close it when it is no longer needed.
const tmp = require('tmp');

tmp.file({ discardDescriptor: true }, function _tempFileCreated(err, path, fd, cleanupCallback) {
  if (err) throw err;
  // fd will be undefined, allowing application to use fs.createReadStream(path)
  // without holding an unused descriptor open.
});

const tmp = require('tmp');

tmp.file({ detachDescriptor: true }, function _tempFileCreated(err, path, fd, cleanupCallback) {
  if (err) throw err;

  cleanupCallback();
  // Application can store data through fd here; the space used will automatically
  // be reclaimed by the operating system when the descriptor is closed or program
  // terminates.
});

Asynchronous directory creation

Creates a directory with mode 0755, prefix will be myTmpDir_.

const tmp = require('tmp');

tmp.dir({ mode: 0o750, prefix: 'myTmpDir_' }, function _tempDirCreated(err, path) {
  if (err) throw err;

  console.log('Dir: ', path);
});

Synchronous directory creation

Again, a synchronous version of the above.

const tmp = require('tmp');

const tmpobj = tmp.dirSync({ mode: 0750, prefix: 'myTmpDir_' });
console.log('Dir: ', tmpobj.name);

mkstemp like, asynchronously

Creates a new temporary directory with mode 0700 and filename like /tmp/tmp-nk2J1u.

IMPORTANT NOTE: template no longer accepts a path. Use the dir option instead if you require tmp to create your temporary filesystem object in a different place than the default tmp.tmpdir.

const tmp = require('tmp');

tmp.dir({ template: 'tmp-XXXXXX' }, function _tempDirCreated(err, path) {
  if (err) throw err;

  console.log('Dir: ', path);
});

mkstemp like, synchronously

This will behave similarly to the asynchronous version.

const tmp = require('tmp');

const tmpobj = tmp.dirSync({ template: 'tmp-XXXXXX' });
console.log('Dir: ', tmpobj.name);

Asynchronous filename generation

Using tmpName() you can create temporary file names asynchronously. The function accepts all standard options, e.g. prefix, postfix, dir, and so on.

You can also leave out the options altogether and just call the function with a callback as first parameter.

const tmp = require('tmp');

const options = {};

tmp.tmpName(options, function _tempNameGenerated(err, path) {
    if (err) throw err;

    console.log('Created temporary filename: ', path);
});

Synchronous filename generation

The tmpNameSync() function works similarly to tmpName(). Again, you can leave out the options altogether and just invoke the function without any parameters.

const tmp = require('tmp');
const options = {};
const tmpname = tmp.tmpNameSync(options);
console.log('Created temporary filename: ', tmpname);

Graceful cleanup

If graceful cleanup is set, tmp will remove all controlled temporary objects on process exit, otherwise the temporary objects will remain in place, waiting to be cleaned up on system restart or otherwise scheduled temporary object removal.

To enforce this, you can call the setGracefulCleanup() method:

const tmp = require('tmp');

tmp.setGracefulCleanup();

Options

All options are optional :)

  • name: a fixed name that overrides random name generation, the name must be relative and must not contain path segments
  • mode: the file mode to create with, falls back to 0o600 on file creation and 0o700 on directory creation
  • prefix: the optional prefix, defaults to tmp
  • postfix: the optional postfix
  • template: mkstemp like filename template, no default, can be either an absolute or a relative path that resolves to a relative path of the system's default temporary directory, must include XXXXXX once for random name generation, e.g. 'foo/bar/XXXXXX'. Absolute paths are also fine as long as they are relative to os.tmpdir(). Any directories along the so specified path must exist, otherwise a ENOENT error will be thrown upon access, as tmp will not check the availability of the path, nor will it establish the requested path for you.
  • dir: the optional temporary directory that must be relative to the system's default temporary directory. absolute paths are fine as long as they point to a location under the system's default temporary directory. Any directories along the so specified path must exist, otherwise a ENOENT error will be thrown upon access, as tmp will not check the availability of the path, nor will it establish the requested path for you.
  • tmpdir: allows you to override the system's root tmp directory
  • tries: how many times should the function try to get a unique filename before giving up, default 3
  • keep: signals that the temporary file or directory should not be deleted on exit, default is false
    • In order to clean up, you will have to call the provided cleanupCallback function manually.
  • unsafeCleanup: recursively removes the created temporary directory, even when it's not empty. default is false
  • detachDescriptor: detaches the file descriptor, caller is responsible for closing the file, tmp will no longer try closing the file during garbage collection
  • discardDescriptor: discards the file descriptor (closes file, fd is -1), tmp will no longer try closing the file during garbage collection