7.1. Obtaining Operating System User Information

(1) os package and subpackage function

• os/exec package, responsible for executing external commands
• Access to input information by os/singal
• os/user queries user accounts by rank or ID

(2) User structure is provided in os/user to represent operating system users

• Uid user id
• Group id of Gid
• Username username
• Name Group Name
• HomeDir User Corresponding Folder Strength

(3) Group s in os/user represent groups to which users belong

• id of Gid group
• Name group name

//Learn_Go/main.go
package main

import (
	"fmt"
	"os/user"
)

func main() {
	u,error := user.Current()   //Get the current user
	if error != nil{
		fmt.Println(error)
		return
	}
	fmt.Println(u.Uid)
	fmt.Println(u.Name)
	fmt.Println(u.Gid)
	fmt.Println(u.HomeDir)
	fmt.Println(u.Username)
}

7.2. System files and directories

(1) There are two ways to create folders in the Go Language Standard Library

MkDir: Requires that folders do not exist and that parent directories must exist in order to create

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	err := os.Mkdir("D:/godir", os.ModeDir)
	if err != nil{
		fmt.Println("Folder creation failed", err)
		return
	}
	fmt.Println("Folder Creation Successful")
}

MkDirAll: If the folder already exists, do not report errors, keep the original file, if the parent directory does not exist to help create

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	err := os.MkdirAll("D:/godir/a/b", os.ModeDir)
	if err != nil{
		fmt.Println("Folder creation failed", err)
		return
	}
	fmt.Println("Folder Creation Successful")
}

(2) Create empty files

Creating a file requires that the file directory already exists

If the file already exists, an empty file is created to overwrite the previous file.

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	f , err := os.Create("D:/godir/test.txt")
	if err != nil{
		fmt.Println("Folder creation failed", err)
		return
	}
	fmt.Println("Folder Creation Successful", f)
}

(3) Rename files or folders

First parameter: the name of the original file, requiring that this path must exist

Second parameter: new folder name

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	err := os.Rename("D:/godir","D:/godir11")
	if err != nil{
		fmt.Println("Rename failed", err)
		return
	}
	fmt.Println("Successful renaming")
}

Rename files

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	err := os.Rename("D:/godir11/test.txt","D:/godir11/test11.txt")
	if err != nil{
		fmt.Println("Rename failed", err)
		return
	}
	fmt.Println("Successful renaming")
}

(4) Getting folder information

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	f,err := os.Open("D:/godir11/test11.txt")
	if err != nil{
		fmt.Println("File acquisition failure", err)
		return
	}
	fileInfo,err := f.Stat()
	if err != nil{
		fmt.Println("Failure to obtain file information",err)
		return
	}
	fmt.Println(fileInfo.Size())          //file size
	fmt.Println(fileInfo.ModTime())      //Final Modification Time of Documents
	fmt.Println(fileInfo.Mode())         //File mode-rw-rw-rw-
	fmt.Println(fileInfo.IsDir())         //Is it a directory false?
	fmt.Println(fileInfo.Name())         //File name test11.txt
}

(5) Delete files or folders

Remove: Deleted content can only be a file or empty folder and must exist

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	err := os.Remove("D:/godir11")
	if err != nil{
		fmt.Println("Delete failed", err)
		return
	}
	fmt.Println("Successful deletion")
}

//Result
//Delete failed remove D:/godir11: The directory is not empty.

RemoveAll

• Delete folders as long as they exist
• Documents will be deleted regardless of whether they have content or not.
• Delete files if they are files

//Learn_Go/main.go
package main

import (
	"fmt"
	"os"
)

func main() {
	err := os.RemoveAll("D:/godir11")
	if err != nil{
		fmt.Println("Delete failed", err)
		return
	}
	fmt.Println("Successful deletion")
}

//Result
//Successful deletion