File Paths · Tuck

The filepath package provides functions to parse and construct file paths in a way that is portable between operating systems; dir/file on Linux vs. dir\file on Windows, for example.

package main

import (
	"fmt"
	"path/filepath"
	"strings"
)

func main() {

Join should be used to construct paths in a portable way. It takes any number of arguments and constructs a hierarchical path from them.

	p := filepath.Join("dir1", "dir2", "filename")
	fmt.Println("p:", p)

You should always use Join instead of concatenating /s or \s manually. In addition to providing portability, Join will also normalize paths by removing superfluous separators and directory changes.

	fmt.Println(filepath.Join("dir1//", "filename"))
	fmt.Println(filepath.Join("dir1/../dir1", "filename"))

Dir and Base can be used to split a path to the directory and the file. Alternatively, Split will return both in the same call.

	fmt.Println("Dir(p):", filepath.Dir(p))
	fmt.Println("Base(p):", filepath.Base(p))

We can check whether a path is absolute.

	fmt.Println(filepath.IsAbs("dir/file"))
	fmt.Println(filepath.IsAbs("/dir/file"))

	filename := "config.json"

Some file names have extensions following a dot. We can split the extension out of such names with Ext.

	ext := filepath.Ext(filename)
	fmt.Println(ext)

To find the file's name with the extension removed, use strings.TrimSuffix.

	fmt.Println(strings.TrimSuffix(filename, ext))

Rel finds a relative path between a base and a target. It returns an error if the target cannot be made relative to base.

	rel, err := filepath.Rel("a/b", "a/b/t/file")
	if err != nil {
		panic(err)
	}
	fmt.Println(rel)

	rel, err = filepath.Rel("a/b", "a/c/t/file")
	if err != nil {
		panic(err)
	}
	fmt.Println(rel)

Match tests a name against a shell pattern; Clean tidies a path.

	ok, _ := filepath.Match("*.go", "main.go")
	fmt.Println(ok, filepath.Clean("/a/./b/../c/"))
}

$ go run ./73_file_paths
p: dir1/dir2/filename
dir1/filename
dir1/filename
Dir(p): dir1/dir2
Base(p): filename
false
true
.json
config
t/file
../c/t/file
true /a/c

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