Golang File Paths | Portable Path Operations

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

// 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)
}