Golang : How to get Unix file descriptor for console and file
A short tutorial showing you how to obtain the Unix file descriptor for terminal/console and file in Golang with the os
package. Basically, there are 3 file descriptors under Unix/Linux environment :
- 0 for input
- 1 for output
- 3 for file
and knowing this information can be helpful in situation when you want to test if a given variable is a file or console.
Here we go!
package main
import (
"fmt"
"os"
)
func main() {
// get console unix file descriptor
outputFileDesc := int(os.Stdout.Fd())
outputName := os.Stdout.Name()
fmt.Println("Terminal or console output Unix file descriptor : ", outputFileDesc)
fmt.Println("output Unix file descriptor name : ", outputName)
fmt.Println("------------------------")
inputFileDesc := int(os.Stdin.Fd())
inputName := os.Stdin.Name()
fmt.Println("Terminal or console input Unix file descriptor : ", inputFileDesc)
fmt.Println("input Unix file descriptor name : ", inputName)
fmt.Println("------------------------")
// get a file unix file descriptor
file, err := os.Open("file.data")
if err != nil {
fmt.Println(err)
os.Exit(1)
}
fileDescriptor := int(file.Fd()) // get the unix descriptor
fileDescriptorName := file.Name() // get the file name
file.Close()
fmt.Printf("%s Unix file descriptor : %d \n", fileDescriptorName, fileDescriptor)
}
Output :
Terminal or console output Unix file descriptor : 1
output Unix file descriptor name : /dev/stdout
------------------------
Terminal or console input Unix file descriptor : 0
input Unix file descriptor name : /dev/stdin
------------------------
file.data Unix file descriptor : 3
Happy coding!
References :
https://golang.org/pkg/os/#File.Fd
https://socketloop.com/references/golang-os-file-fd-function-example
http://www.theunixschool.com/2010/08/unix-file-descriptors.html
By Adam Ng
IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.
Advertisement
Tutorials
+46.7k Golang : Encode image to base64 example
+11.9k How to tell if a binary(executable) file or web application is built with Golang?
+10.6k Golang : Meaning of omitempty in struct's field tag
+22.1k Golang : Upload big file (larger than 100MB) to AWS S3 with multipart upload
+8.1k Golang : Ways to recover memory during run time.
+15.5k Golang : Get query string value on a POST request
+11.1k Golang : How to transmit update file to client by HTTP request example
+22.4k Golang : Match strings by wildcard patterns with filepath.Match() function
+10k Random number generation with crypto/rand in Go
+14.8k Golang : How to check if your program is running in a terminal
+20.4k Golang : How to get struct tag and use field name to retrieve data?
+11.1k Android Studio : Checkbox for user to select options example