path - Expand tilde to home directory

Question

I have a program that accepts a destination folder where files will be created. My program should be able to handle absolute paths as well as relative paths. My problem is that I don't know how to expand ~ to the home directory.

My function to expand the destination looks like this. If the path given is absolute it does nothing otherwise it joins the relative path with the current working directory.

import "path"
import "os"

// var destination *String is the user input

func expandPath() {
        if path.IsAbs(*destination) {
                return
        }
        cwd, err := os.Getwd()
        checkError(err)
        *destination = path.Join(cwd, *destination)
}

Since path.Join doesn't expand ~ it doesn't work if the user passes something like ~/Downloads as the destination.

How should I solve this in a cross platform way?

question from:https://stackoverflow.com/questions/17609732/expand-tilde-to-home-directory

Answer 1

Normally, the ~ is expanded by the shell before your program sees it.
Adjust how your program acquires its arguments from the command line in a way compatible with the shell expansion mechanism.

One of the possible problems is using exec.Command like this:

cmd := exec.Command("some-binary", someArg) // say 'someArg' is "~/foo"

which will not get expanded. You can, for example use instead:

cmd := exec.Command("sh", "-c", fmt.Sprintf("'some-binary %q'", someArg))

which will get the standard ~ expansion from the shell.

EDIT: fixed the 'sh -c' example.