Documentation

Overview

    Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths.

    The filepath package uses either forward slashes or backslashes, depending on the operating system. To process paths such as URLs that always use forward slashes regardless of the operating system, see the path package.

    Index

    Examples

    Constants

    View Source
    const (
    	Separator     = os.PathSeparator
    	ListSeparator = os.PathListSeparator
    )

    Variables

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

      ErrBadPattern indicates a pattern was malformed.

      View Source
      var SkipDir error = fs.SkipDir

        SkipDir is used as a return value from WalkFuncs to indicate that the directory named in the call is to be skipped. It is not returned as an error by any function.

        Functions

        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.

            Example
            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 ".".

              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.

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

                    Example
                    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.

                      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 HasPrefix

                        func HasPrefix(p, prefix string) bool

                          HasPrefix exists for historical compatibility and should not be used.

                          Deprecated: HasPrefix does not respect path boundaries and does not ignore case when required.

                          func IsAbs

                          func IsAbs(path string) bool

                            IsAbs reports whether the path is absolute.

                            Example
                            Output:
                            
                            On Unix:
                            true
                            false
                            false
                            false
                            true
                            false
                            

                            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.

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

                              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.

                                Example
                                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.

                                  Example
                                  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.

                                    Example
                                    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.

                                      Example
                                      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.

                                            Example
                                            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

                                            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.

                                              Types

                                              type WalkFunc

                                              type WalkFunc func(path string, info fs.FileInfo, err error) error

                                                WalkFunc is the type of the function called by Walk to visit each each file 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 file named "a" in that directory, the walk function will be called with argument "dir/a".

                                                The directory and file are joined with Join, which may clean the directory name: if Walk is called with the root argument "x/../dir" and finds a file named "a" in that directory, the walk function will be 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 value SkipDir, Walk skips the current directory (path if info.IsDir() is true, otherwise path's parent directory). Otherwise, if the function returns a non-nil error, Walk stops entirely and returns that error.

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

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

                                                First, if an os.Lstat on the root directory or any directory or file in the tree fails, Walk calls the function with path set to that directory or file's path, info set to nil, and err set to the error from os.Lstat.

                                                Second, if a directory's Readdirnames method fails, Walk calls the function with path set to the directory's path, info, set to an fs.FileInfo describing the directory, and err set to the error from Readdirnames.