Hands-On System Programming with Go

User and group ID

Another piece of information that can be handy is the current user and the groups that the process belongs to. A typical user case could be to compare them with a file-specific permission.

The os package offers the following functions:

• os.Getuid(): Returns the user ID of the process owner
• os.Getgid(): Returns the group ID of the process owner
• os.Getgroups(): Returns additional group IDs of the process owner

We can see that these three functions return IDs in their numerical form:

package mainimport (    "fmt"    "os")func main() {    fmt.Println("User ID:", os.Getuid())    fmt.Println("Group ID:", os.Getgid())    groups, err := os.Getgroups()    if err != nil {        fmt.Println(err)        return    }    fmt.Println("Group IDs:", groups)}

The full example ...