How to use the command 'gow' (with examples)

The gow command is a utility developed to enhance the Go programming language development experience. It monitors Go files for any changes and automatically restarts the application when a modification is detected. This tool can be particularly useful for developers who require immediate feedback from their applications as they develop, test, or debug them. By automating the restart process, gow eliminates the monotonous task of manually stopping and starting the application, thereby improving productivity and reducing the risk of error.

Use case 1: Start and Watch the Current Directory

Code:

gow run .

Motivation:

When actively developing a Go application, developers often need to make frequent changes and see how those changes affect the running application. By using gow run ., the command runs the application in the current directory and constantly watches for any changes to Go files, automatically restarting the application upon detection of a change. This eliminates the need to manually restart the application, thus increasing development efficiency.

Explanation:

• gow: Invokes the gow command.
• run: This command is used to execute a Go application.
• .: This refers to the current directory, indicating that the command should execute and watch all Go files in the current directory.

Example Output:

Starting: ./main
[gow] listening for changes...
[gow] detected change in main.go, restarting...
Starting: ./main

Use case 2: Start the Application with Specified Arguments

Code:

gow run . argument1 argument2 ...

Motivation:

In some situations, an application may require specific runtime arguments to control its behavior, such as specifying configuration files, setting up environmental variables, or passing data to process. By providing arguments directly within the gow command, developers can run their applications with necessary parameters while still benefiting from automated restarts upon file changes.

Explanation:

• gow: Initiates the gow command.
• run: Instructs to execute the Go application.
• .: The current directory, indicating where the application resides.
• argument1 argument2 ...: Custom arguments that are passed to the application upon execution. These can be any string of text relevant to the application’s functionality.

Example Output:

Starting: ./main argument1 argument2
[gow] listening for changes...
[gow] detected change in utils.go, restarting...
Starting: ./main argument1 argument2

Use case 3: Watch Subdirectories in Verbose Mode

Code:

gow -v -w=path/to/directory1,path/to/directory2,... run .

Motivation:

Complex Go applications often span multiple directories. To ensure gow effectively tracks changes across all relevant files, developers can employ this command to specify additional subdirectories that need monitoring. With the -v flag, developers receive verbose output, which provides detailed logging and helps trace which files induce application restarts.

Explanation:

• gow: Activates the gow command.
• -v: Sets verbose mode, giving detailed output of the monitoring process.
• -w=path/to/directory1,path/to/directory2,...: Specifies additional directories to watch for changes.
• run: Indicates the execution of the Go application.
• .: Denotes the current directory for the primary application execution.

Example Output:

[gow] watching directories: path/to/directory1, path/to/directory2
Starting: ./main
[gow] listening for changes...
[gow] detected change in path/to/directory1/file.go, restarting...
Starting: ./main

Use case 4: Watch the Specified File Extensions

Code:

gow -e=go,html run .

Motivation:

Some applications may require monitoring of files beyond Go source files, such as templates or static content files that might need to trigger application restarts when changed. By using the -e flag, developers can instruct gow to additionally watch files with specific extensions like HTML, CSS, or any other extensions critical to the application’s functionality.

Explanation:

• gow: Calls the gow command.
• -e=go,html: Specifies the file extensions to watch, enabling gow to restart the application when files with these extensions are modified.
• run: Executes the Go application.
• .: Denotes the current directory from where the application should be run.

Example Output:

[gow] watching extensions: go, html
Starting: ./main
[gow] listening for changes...
[gow] detected change in index.html, restarting...
Starting: ./main

Use case 5: Display Help

Code:

gow -h

Motivation:

For both new users and seasoned developers who may need a refresher on available options, using the help flag provides a concise overview of all the command parameters and usage instructions. This is useful when familiarizing oneself with the command or exploring additional features.

Explanation:

• gow: Executes the gow command.
• -h: Calls the help option, displaying available commands and usage instructions for gow.

Example Output:

Usage of gow:
  -e string
    	set file extensions to watch (ex: go,html) (default "go")
  -h	display help for gow
  -v	verbose output
  -w set directories to watch (default ".")

Conclusion:

The gow command is a potent tool for Go developers who seek an efficient and automated workflow. By using gow, developers can keep their focus on writing and modifying code, without the constant interruption of manually restarting their application after each modification. Through its various use cases, such as specifying directories or file extensions, gow offers adaptable solutions that cater to complex projects and unique application requirements, enhancing both productivity and development comfort.