tmp-promise

A simple utility for creating temporary files or directories.

The tmp package with promises support. If you want to use tmp with async/await then this helper might be for you.

This documentation is mostly copied from that package's - but with promise usage instead of callback usage adapted.

Installation

npm i tmp-promise

Note: Node.js 8+ is supported - older versions of Node.js are not supported by the Node.js foundation. If you need to use an older version of Node.js install tmp-promise@1.10

npm i tmp-promise@1.1.0

About

This adds promises support to a widely used library. This package is used to create temporary files and directories in a Node.js environment.

tmp-promise offers both an asynchronous and a synchronous API. For all API calls, all the parameters are optional.

Internally, 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, and the destination directory can also be set.

tmp-promise also uses promise disposers to provide a nice way to perform cleanup when you're done working with the files.

Usage (API Reference)

Asynchronous file creation

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

With Node.js 10 and es - modules:

1import { file } from 'tmp-promise'
2
3(async () => {
4  const {fd, path, cleanup} = await file();
5  // work with file here in fd
6  cleanup();
7})(); 

Or the older way:

1var tmp = require('tmp-promise');
2
3tmp.file().then(o => {  
4  console.log("File: ", o.path);
5  console.log("Filedescriptor: ", o.fd);
6  
7  // If we don't need the file anymore we could manually call cleanup
8  // But that is not necessary if we didn't pass the keep option because the library
9  // will clean after itself.
10  o.cleanup();
11});

Simple temporary file creation with a disposer:

With Node.js 10 and es - modules:

1import { withFile } from 'tmp-promise'
2
3withFile(async ({path, fd}) => {
4  // when this function returns or throws - release the file 
5  await doSomethingWithFile(db);
6});

Or the older way:

1tmp.withFile(o => {
2  console.log("File: ", o.path);
3  console.log("Filedescriptor: ", o.fd);
4  // the file remains opens until the below promise resolves
5  return somePromiseReturningFn();
6}).then(v => {
7  // file is closed here automatically, v is the value of somePromiseReturningFn
8});

Synchronous file creation

A synchronous version of the above.

1var tmp = require('tmp-promise');
2
3var tmpobj = tmp.fileSync();
4console.log("File: ", tmpobj.name);
5console.log("Filedescriptor: ", tmpobj.fd);
6  
7// If we don't need the file anymore we could manually call the removeCallback
8// But that is not necessary if we didn't pass the keep option because the library
9// will clean after itself.
10tmpobj.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.

1var tmp = require('tmp-promise');
2
3tmp.dir().then(o => {
4  console.log("Dir: ", o.path);
5  
6  // Manual cleanup
7  o.cleanup();
8});

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

You can also use a disposer here which takes care of cleanup automatically:

1var tmp = require('tmp-promise');
2
3tmp.withDir(o => {
4  console.log("Dir: ", o.path);
5  
6  // automatic cleanup when the below promise resolves
7  return somePromiseReturningFn(); 
8}).then(v => {
9  // the directory has been cleaned here
10});

Synchronous directory creation

A synchronous version of the above.

1var tmp = require('tmp-promise');
2
3var tmpobj = tmp.dirSync();
4console.log("Dir: ", tmpobj.name);
5// Manual cleanup
6tmpobj.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.

1var tmp = require('tmp-promise');
2
3tmp.tmpName().then(path => {
4    console.log("Created temporary filename: ", path);
5});

Synchronous filename generation

A synchronous version of the above.

1var tmp = require('tmp-promise');
2
3var name = tmp.tmpNameSync();
4console.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.

1var tmp = require('tmp-promise');
2
3tmp.file({ mode: 0644, prefix: 'prefix-', postfix: '.txt' }).then(o => {
4  console.log("File: ", o.path);
5  console.log("Filedescriptor: ", o.fd); 
6});

Synchronous file creation

A synchronous version of the above.

1var tmp = require('tmp-promise');
2
3var tmpobj = tmp.fileSync({ mode: 0644, prefix: 'prefix-', postfix: '.txt' });
4console.log("File: ", tmpobj.name);
5console.log("Filedescriptor: ", tmpobj.fd);

Asynchronous directory creation

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

1var tmp = require('tmp-promise');
2
3tmp.dir({ mode: 0750, prefix: 'myTmpDir_' }).then(o => {
4  console.log("Dir: ", o.path);
5});

Synchronous directory creation

Again, a synchronous version of the above.

1var tmp = require('tmp-promise');
2
3var tmpobj = tmp.dirSync({ mode: 0750, prefix: 'myTmpDir_' });
4console.log("Dir: ", tmpobj.name);

mkstemp like, asynchronously

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

1var tmp = require('tmp-promise');
2tmp.dir({ template: '/tmp/tmp-XXXXXX' }).then(console.log);

mkstemp like, synchronously

This will behave similarly to the asynchronous version.

1var tmp = require('tmp-promise');
2
3var tmpobj = tmp.dirSync({ template: '/tmp/tmp-XXXXXX' });
4console.log("Dir: ", tmpobj.name);

Asynchronous filename generation

The tmpName() function accepts the prefix, postfix, dir, etc. parameters also:

1var tmp = require('tmp-promise');
2
3tmp.tmpName({ template: '/tmp/tmp-XXXXXX' }).then(path =>
4    console.log("Created temporary filename: ", path);
5);

Synchronous filename generation

The tmpNameSync() function works similarly to tmpName().

1var tmp = require('tmp-promise');
2var tmpname = tmp.tmpNameSync({ template: '/tmp/tmp-XXXXXX' });
3console.log("Created temporary filename: ", tmpname);

Graceful cleanup

One may want to cleanup the temporary files even when an uncaught exception occurs. To enforce this, you can call the setGracefulCleanup() method:

1var tmp = require('tmp');
2
3tmp.setGracefulCleanup();

Options

All options are optional :)

• mode: the file mode to create with, it fallbacks to 0600 on file creation and 0700 on directory creation
• prefix: the optional prefix, fallbacks to tmp- if not provided
• postfix: the optional postfix, fallbacks to .tmp on file creation
• template: mkstemp like filename template, no default
• dir: the optional temporary directory, fallbacks to system default (guesses from environment)
• 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, means delete
  • Please keep in mind that it is recommended in this case to call the provided cleanupCallback function manually.
• unsafeCleanup: recursively removes the created temporary directory, even when it's not empty. default is false