How to Retrieve the Number of Hard Links to a File in Go?

Retrieving the Number of Hard Links to a File in Go

The Go standard library provides the FileInfo interface for accessing file metadata obtained via the stat() system call. However, this interface does not directly expose the number of hard links to a file, which is a useful piece of information in certain scenarios.

Solution

To retrieve the number of hard links to a file in Go, we need to access the underlying system data associated with the FileInfo object. This can be done by casting the Sys() method of FileInfo to a relevant system-dependent type, as demonstrated in the example below:

<code class="go">package main

import (
    "fmt"
    "os"
    "syscall"
)

func main() {
    fi, err := os.Stat("filename")
    if err != nil {
        fmt.Println(err)
        return
    }
    nlink := uint64(0)
    if sys := fi.Sys(); sys != nil {
        if stat, ok := sys.(*syscall.Stat_t); ok {
            nlink = uint64(stat.Nlink)
        }
    }
    fmt.Println(nlink)
}</code>

In the example above, we first obtain the FileInfo object for the specified file. We then check if the Sys() method returns a non-nil value and cast it to the *syscall.Stat_t type, which is defined in the syscall package. The Nlink field of the *syscall.Stat_t structure contains the number of hard links to the file.

Example Output

Running the example program with an existing file named "filename" produces the following output:

1

This indicates that the file has one hard link, which is the default value.

Therefore, by accessing the underlying system data associated with the FileInfo object, we can retrieve the number of hard links to a specific file in Go.

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