Creating a temporary file

Creating a temporary file

How to:

In Go, the ioutil package originally provided utilities for temporary file creation. However, Go 1.16 promoted the use of the os and io/ioutil package’s functions into more organized spots. Now, the os and io packages are preferred for handling temporary files.

Here’s a step-by-step guide to creating, writing to, and deleting a temporary file:

  1. Create a Temporary File:

Using the os.CreateTemp function, you can create a temporary file. Without specifying a directory, it uses the default temp folder of your OS.

package main

import (

func main() {
    tmpFile, err := ioutil.TempFile("", "example.*.txt")
    if err != nil {
    log.Printf("Created temporary file: %s\n", tmpFile.Name())

    defer os.Remove(tmpFile.Name()) // Clean up
  1. Write to the Temporary File:

Writing to the file can be achieved with the Write method or other writing functions from the io or bufio packages.

_, err = tmpFile.Write([]byte("Hello, World!"))
if err != nil {
  1. Read from the Temporary File:

Reading follows similarly, utilizing the file’s Read method, or using utilities from the io or bufio packages.

data, err := ioutil.ReadFile(tmpFile.Name())
if err != nil {
log.Printf("Data read: %s\n", string(data))
  1. Delete the Temporary File:

While the defer os.Remove(tmpFile.Name()) statement at the creation phase ensures the temporary file is deleted after the program terminates, explicit deletion can be managed as needed.

Sample Output:

2023/04/01 15:00:00 Created temporary file: /tmp/example.123456.txt
2023/04/01 15:00:00 Data read: Hello, World!

Deep Dive

The mechanism behind Go’s handling of temporary files has evolved. Initially, creating temporary files was predominantly managed by the now-deprecated ioutil.TempFile function, reflecting broader trends in software development towards more secure and efficient file handling practices. The move to integrate these functionalities into the os and io packages with Go 1.16 signifies a broader push towards streamlining the language’s standard library and encouraging the use of more unified and cohesive APIs.

While using temporary files is a common and often essential practice in programming, it’s important to note that relying too heavily on them for storing large amounts of data or for long-term tasks can lead to performance issues. Moreover, when the creation of temporary files is not tightly controlled or when they’re not adequately cleaned up, it can lead to resource leaks which could negatively impact the file system. In scenarios that demand persistent storage or require handling substantial data streams, alternatives such as databases or in-memory data stores often offer better performance and reliability compared to temporary files.