filepath

func Abs ¶

func Abs(path string) (string, error)

Abs returns an absolute representation of path. If the path is not absolute it will be joined with the current working directory to turn it into an absolute path. The absolute path name for a given file is not guaranteed to be unique. Abs calls Clean on the result.

func Base ¶

func Base(path string) string

Base returns the last element of path. Trailing path separators are removed before extracting the last element. If the path is empty, Base returns ".". If the path consists entirely of separators, Base returns a single separator.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(filepath.Base("/foo/bar/baz.js"))
	fmt.Println(filepath.Base("/foo/bar/baz"))
	fmt.Println(filepath.Base("/foo/bar/baz/"))
	fmt.Println(filepath.Base("dev.txt"))
	fmt.Println(filepath.Base("../todo.txt"))
	fmt.Println(filepath.Base(".."))
	fmt.Println(filepath.Base("."))
	fmt.Println(filepath.Base("/"))
	fmt.Println(filepath.Base(""))

}

Output:

On Unix:
baz.js
baz
baz
dev.txt
todo.txt
..
.
/
.

func Clean ¶

func Clean(path string) string

Clean returns the shortest path name equivalent to path by purely lexical processing. It applies the following rules iteratively until no further processing can be done:

1. Replace multiple Separator elements with a single one.
2. Eliminate each . path name element (the current directory).
3. Eliminate each inner .. path name element (the parent directory) along with the non-.. element that precedes it.
4. Eliminate .. elements that begin a rooted path: that is, replace "/.." by "/" at the beginning of a path, assuming Separator is '/'.

The returned path ends in a slash only if it represents a root directory, such as "/" on Unix or `C:\` on Windows.

Finally, any occurrences of slash are replaced by Separator.

If the result of this process is an empty string, Clean returns the string ".".

On Windows, Clean does not modify the volume name other than to replace occurrences of "/" with `\`. For example, Clean("//host/share/../x") returns `\\host\share\x`.

See also Rob Pike, “Lexical File Names in Plan 9 or Getting Dot-Dot Right,” https://9p.io/sys/doc/lexnames.html

func Dir ¶

func Dir(path string) string

Dir returns all but the last element of path, typically the path's directory. After dropping the final element, Dir calls Clean on the path and trailing slashes are removed. If the path is empty, Dir returns ".". If the path consists entirely of separators, Dir returns a single separator. The returned path does not end in a separator unless it is the root directory.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(filepath.Dir("/foo/bar/baz.js"))
	fmt.Println(filepath.Dir("/foo/bar/baz"))
	fmt.Println(filepath.Dir("/foo/bar/baz/"))
	fmt.Println(filepath.Dir("/dirty//path///"))
	fmt.Println(filepath.Dir("dev.txt"))
	fmt.Println(filepath.Dir("../todo.txt"))
	fmt.Println(filepath.Dir(".."))
	fmt.Println(filepath.Dir("."))
	fmt.Println(filepath.Dir("/"))
	fmt.Println(filepath.Dir(""))

}

Output:

On Unix:
/foo/bar
/foo/bar
/foo/bar/baz
/dirty/path
.
..
.
.
/
.

func EvalSymlinks ¶

func EvalSymlinks(path string) (string, error)

EvalSymlinks returns the path name after the evaluation of any symbolic links. If path is relative the result will be relative to the current directory, unless one of the components is an absolute symbolic link. EvalSymlinks calls Clean on the result.

func Ext ¶

func Ext(path string) string

Ext returns the file name extension used by path. The extension is the suffix beginning at the final dot in the final element of path; it is empty if there is no dot.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	fmt.Printf("No dots: %q\n", filepath.Ext("index"))
	fmt.Printf("One dot: %q\n", filepath.Ext("index.js"))
	fmt.Printf("Two dots: %q\n", filepath.Ext("main.test.js"))
}

Output:

No dots: ""
One dot: ".js"
Two dots: ".js"

func FromSlash ¶

func FromSlash(path string) string

FromSlash returns the result of replacing each slash ('/') character in path with a separator character. Multiple slashes are replaced by multiple separators.

See also the Localize function, which converts a slash-separated path as used by the io/fs package to an operating system path.

func Glob ¶

func Glob(pattern string) (matches []string, err error)

Glob returns the names of all files matching pattern or nil if there is no matching file. The syntax of patterns is the same as in Match. The pattern may describe hierarchical names such as /usr/*/bin/ed (assuming the Separator is '/').

Glob ignores file system errors such as I/O errors reading directories. The only possible returned error is ErrBadPattern, when pattern is malformed.

func IsAbs ¶

func IsAbs(path string) bool

IsAbs reports whether the path is absolute.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(filepath.IsAbs("/home/gopher"))
	fmt.Println(filepath.IsAbs(".bashrc"))
	fmt.Println(filepath.IsAbs(".."))
	fmt.Println(filepath.IsAbs("."))
	fmt.Println(filepath.IsAbs("/"))
	fmt.Println(filepath.IsAbs(""))

}

Output:

On Unix:
true
false
false
false
true
false

func IsLocal ¶ added in go1.20

func IsLocal(path string) bool

IsLocal reports whether path, using lexical analysis only, has all of these properties:

• is within the subtree rooted at the directory in which path is evaluated
• is not an absolute path
• is not empty
• on Windows, is not a reserved name such as "NUL"

If IsLocal(path) returns true, then Join(base, path) will always produce a path contained within base and Clean(path) will always produce an unrooted path with no ".." path elements.

IsLocal is a purely lexical operation. In particular, it does not account for the effect of any symbolic links that may exist in the filesystem.

func Join ¶

func Join(elem ...string) string

Join joins any number of path elements into a single path, separating them with an OS specific Separator. Empty elements are ignored. The result is Cleaned. However, if the argument list is empty or all its elements are empty, Join returns an empty string. On Windows, the result will only be a UNC path if the first non-empty element is a UNC path.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(filepath.Join("a", "b", "c"))
	fmt.Println(filepath.Join("a", "b/c"))
	fmt.Println(filepath.Join("a/b", "c"))
	fmt.Println(filepath.Join("a/b", "/c"))

	fmt.Println(filepath.Join("a/b", "../../../xyz"))

}

Output:

On Unix:
a/b/c
a/b/c
a/b/c
a/b/c
../xyz

func Localize ¶ added in go1.23.0

func Localize(path string) (string, error)

Localize converts a slash-separated path into an operating system path. The input path must be a valid path as reported by io/fs.ValidPath.

Localize returns an error if the path cannot be represented by the operating system. For example, the path a\b is rejected on Windows, on which \ is a separator character and cannot be part of a filename.

The path returned by Localize will always be local, as reported by IsLocal.

func Match ¶

func Match(pattern, name string) (matched bool, err error)

Match reports whether name matches the shell file name pattern. The pattern syntax is:

pattern:
	{ term }
term:
	'*'         matches any sequence of non-Separator characters
	'?'         matches any single non-Separator character
	'[' [ '^' ] { character-range } ']'
	            character class (must be non-empty)
	c           matches character c (c != '*', '?', '\\', '[')
	'\\' c      matches character c

character-range:
	c           matches character c (c != '\\', '-', ']')
	'\\' c      matches character c
	lo '-' hi   matches character c for lo <= c <= hi

Match requires pattern to match all of name, not just a substring. The only possible returned error is ErrBadPattern, when pattern is malformed.

On Windows, escaping is disabled. Instead, '\\' is treated as path separator.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(filepath.Match("/home/catch/*", "/home/catch/foo"))
	fmt.Println(filepath.Match("/home/catch/*", "/home/catch/foo/bar"))
	fmt.Println(filepath.Match("/home/?opher", "/home/gopher"))
	fmt.Println(filepath.Match("/home/\\*", "/home/*"))

}

Output:

On Unix:
true <nil>
false <nil>
true <nil>
true <nil>

func Rel ¶

func Rel(basepath, targpath string) (string, error)

Rel returns a relative path that is lexically equivalent to targpath when joined to basepath with an intervening separator. That is, Join(basepath, Rel(basepath, targpath)) is equivalent to targpath itself. On success, the returned path will always be relative to basepath, even if basepath and targpath share no elements. An error is returned if targpath can't be made relative to basepath or if knowing the current working directory would be necessary to compute it. Rel calls Clean on the result.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	paths := []string{
		"/a/b/c",
		"/b/c",
		"./b/c",
	}
	base := "/a"

	fmt.Println("On Unix:")
	for _, p := range paths {
		rel, err := filepath.Rel(base, p)
		fmt.Printf("%q: %q %v\n", p, rel, err)
	}

}

Output:

On Unix:
"/a/b/c": "b/c" <nil>
"/b/c": "../b/c" <nil>
"./b/c": "" Rel: can't make ./b/c relative to /a

func Split ¶

func Split(path string) (dir, file string)

Split splits path immediately following the final Separator, separating it into a directory and file name component. If there is no Separator in path, Split returns an empty dir and file set to path. The returned values have the property that path = dir+file.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	paths := []string{
		"/home/arnie/amelia.jpg",
		"/mnt/photos/",
		"rabbit.jpg",
		"/usr/local//go",
	}
	fmt.Println("On Unix:")
	for _, p := range paths {
		dir, file := filepath.Split(p)
		fmt.Printf("input: %q\n\tdir: %q\n\tfile: %q\n", p, dir, file)
	}
}

Output:

On Unix:
input: "/home/arnie/amelia.jpg"
	dir: "/home/arnie/"
	file: "amelia.jpg"
input: "/mnt/photos/"
	dir: "/mnt/photos/"
	file: ""
input: "rabbit.jpg"
	dir: ""
	file: "rabbit.jpg"
input: "/usr/local//go"
	dir: "/usr/local//"
	file: "go"

func SplitList ¶

func SplitList(path string) []string

SplitList splits a list of paths joined by the OS-specific ListSeparator, usually found in PATH or GOPATH environment variables. Unlike strings.Split, SplitList returns an empty slice when passed an empty string.

package main

import (
	"fmt"
	"path/filepath"
)

func main() {
	fmt.Println("On Unix:", filepath.SplitList("/a/b/c:/usr/bin"))
}

Output:

On Unix: [/a/b/c /usr/bin]

func ToSlash ¶

func ToSlash(path string) string

ToSlash returns the result of replacing each separator character in path with a slash ('/') character. Multiple separators are replaced by multiple slashes.

func VolumeName ¶

func VolumeName(path string) string

VolumeName returns leading volume name. Given "C:\foo\bar" it returns "C:" on Windows. Given "\\host\share\foo" it returns "\\host\share". On other platforms it returns "".

func Walk ¶

func Walk(root string, fn WalkFunc) error

Walk walks the file tree rooted at root, calling fn for each file or directory in the tree, including root.

All errors that arise visiting files and directories are filtered by fn: see the WalkFunc documentation for details.

The files are walked in lexical order, which makes the output deterministic but requires Walk to read an entire directory into memory before proceeding to walk that directory.

Walk does not follow symbolic links.

Walk is less efficient than WalkDir, introduced in Go 1.16, which avoids calling os.Lstat on every visited file or directory.

//go:build !windows && !plan9

package main

import (
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
)

func prepareTestDirTree(tree string) (string, error) {
	tmpDir, err := os.MkdirTemp("", "")
	if err != nil {
		return "", fmt.Errorf("error creating temp directory: %v\n", err)
	}

	err = os.MkdirAll(filepath.Join(tmpDir, tree), 0755)
	if err != nil {
		os.RemoveAll(tmpDir)
		return "", err
	}

	return tmpDir, nil
}

func main() {
	tmpDir, err := prepareTestDirTree("dir/to/walk/skip")
	if err != nil {
		fmt.Printf("unable to create test dir tree: %v\n", err)
		return
	}
	defer os.RemoveAll(tmpDir)
	os.Chdir(tmpDir)

	subDirToSkip := "skip"

	fmt.Println("On Unix:")
	err = filepath.Walk(".", func(path string, info fs.FileInfo, err error) error {
		if err != nil {
			fmt.Printf("prevent panic by handling failure accessing a path %q: %v\n", path, err)
			return err
		}
		if info.IsDir() && info.Name() == subDirToSkip {
			fmt.Printf("skipping a dir without errors: %+v \n", info.Name())
			return filepath.SkipDir
		}
		fmt.Printf("visited file or dir: %q\n", path)
		return nil
	})
	if err != nil {
		fmt.Printf("error walking the path %q: %v\n", tmpDir, err)
		return
	}
}

Output:

On Unix:
visited file or dir: "."
visited file or dir: "dir"
visited file or dir: "dir/to"
visited file or dir: "dir/to/walk"
skipping a dir without errors: skip

func WalkDir ¶ added in go1.16

func WalkDir(root string, fn fs.WalkDirFunc) error

WalkDir walks the file tree rooted at root, calling fn for each file or directory in the tree, including root.

All errors that arise visiting files and directories are filtered by fn: see the fs.WalkDirFunc documentation for details.

The files are walked in lexical order, which makes the output deterministic but requires WalkDir to read an entire directory into memory before proceeding to walk that directory.

WalkDir does not follow symbolic links.

WalkDir calls fn with paths that use the separator character appropriate for the operating system. This is unlike io/fs.WalkDir, which always uses slash separated paths.