const (Separator     =os.PathSeparatorListSeparator =os.PathListSeparator)

var ErrBadPattern =errors.New("syntax error in pattern")

var SkipAllerror =fs.SkipAll

var SkipDirerror =fs.SkipDir

funcAbs¶

func Abs(pathstring) (string,error)

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

funcBase¶

func Base(pathstring)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 mainimport ("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.jsbazbazdev.txttodo.txt.../.

funcClean¶

func Clean(pathstring)string

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

1. Replace multipleSeparator 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, Cleanreturns the string ".".

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

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

funcDir¶

func Dir(pathstring)string

Dir returns all but the last element of path, typically the path's directory.After dropping the final element, Dir callsClean on the path and trailingslashes 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 mainimport ("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...../.

funcEvalSymlinks¶

func EvalSymlinks(pathstring) (string,error)

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

funcExt¶

func Ext(pathstring)string

Ext returns the file name extension used by path.The extension is the suffix beginning at the final dotin the final element of path; it is empty if there isno dot.

package mainimport ("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"

funcFromSlash¶

func FromSlash(pathstring)string

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

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

funcGlob¶

func Glob(patternstring) (matches []string, errerror)

Glob returns the names of all files matching pattern or nilif there is no matching file. The syntax of patterns is the sameas inMatch. The pattern may describe hierarchical names such as/usr/*/bin/ed (assuming theSeparator is '/').

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

funcIsAbs¶

func IsAbs(pathstring)bool

IsAbs reports whether the path is absolute.

package mainimport ("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:truefalsefalsefalsetruefalse

funcIsLocal¶added ingo1.20

func IsLocal(pathstring)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, thenJoin(base, path) will always produce a path contained within base andClean(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 linksthat may exist in the filesystem.

funcJoin¶

func Join(elem ...string)string

Join joins any number of path elements into a single path,separating them with an OS specificSeparator. Empty elementsare ignored. The result is Cleaned. However, if the argumentlist is empty or all its elements are empty, Join returnsan empty string.On Windows, the result will only be a UNC path if the firstnon-empty element is a UNC path.

package mainimport ("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/ca/b/ca/b/ca/b/c../xyz

funcLocalize¶added ingo1.23.0

func Localize(pathstring) (string,error)

Localize converts a slash-separated path into an operating system path.The input path must be a valid path as reported byio/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 separatorcharacter and cannot be part of a filename.

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

funcMatch¶

func Match(pattern, namestring) (matchedbool, errerror)

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 ccharacter-range:c           matches character c (c != '\\', '-', ']')'\\' c      matches character clo '-' 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 isErrBadPattern, when patternis malformed.

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

package mainimport ("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>

funcRel¶

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

Rel returns a relative path that is lexically equivalent to targpath whenjoined 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 ifknowing the current working directory would be necessary to compute it.Rel callsClean on the result.

package mainimport ("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

funcSplit¶

func Split(pathstring) (dir, filestring)

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

package mainimport ("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"

funcSplitList¶

func SplitList(pathstring) []string

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

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

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

funcToSlash¶

func ToSlash(pathstring)string

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

funcVolumeName¶

func VolumeName(pathstring)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 "".

funcWalk¶

func Walk(rootstring, fnWalkFunc)error

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

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

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

Walk does not follow symbolic links.

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

//go:build !windows && !plan9package mainimport ("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

funcWalkDir¶added ingo1.16

func WalkDir(rootstring, fnfs.WalkDirFunc)error

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

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

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

WalkDir does not follow symbolic links.

WalkDir calls fn with paths that use the separator character appropriatefor the operating system. This is unlikeio/fs.WalkDir, which alwaysuses slash separated paths.

typeWalkFunc¶

type WalkFunc func(pathstring, infofs.FileInfo, errerror)error

WalkFunc is the type of the function called byWalk to visit eachfile or directory.

The path argument contains the argument to Walk as a prefix.That is, if Walk is called with root argument "dir" and finds a filenamed "a" in that directory, the walk function will be called withargument "dir/a".

The directory and file are joined with Join, which may clean thedirectory name: if Walk is called with the root argument "x/../dir"and finds a file named "a" in that directory, the walk function willbe called with argument "dir/a", not "x/../dir/a".

The info argument is the fs.FileInfo for the named path.

The error result returned by the function controls how Walk continues.If the function returns the special valueSkipDir, Walk skips thecurrent directory (path if info.IsDir() is true, otherwise path'sparent directory). If the function returns the special valueSkipAll,Walk skips all remaining files and directories. Otherwise, if the functionreturns a non-nil error, Walk stops entirely and returns that error.

The err argument reports an error related to path, signaling that Walkwill not walk into that directory. The function can decide how tohandle that error; as described earlier, returning the error willcause Walk to stop walking the entire tree.

Walk calls the function with a non-nil err argument in two cases.

First, if anos.Lstat on the root directory or any directory or filein the tree fails, Walk calls the function with path set to thatdirectory or file's path, info set to nil, and err set to the errorfrom os.Lstat.

Second, if a directory's Readdirnames method fails, Walk calls thefunction with path set to the directory's path, info, set to anfs.FileInfo describing the directory, and err set to the error fromReaddirnames.