fs

func FormatDirEntry ¶ added in go1.21.0

func FormatDirEntry(dir DirEntry) string

FormatDirEntry returns a formatted version of dir for human readability. Implementations of DirEntry can call this from a String method. The outputs for a directory named subdir and a file named hello.go are:

d subdir/
- hello.go

func FormatFileInfo ¶ added in go1.21.0

func FormatFileInfo(info FileInfo) string

FormatFileInfo returns a formatted version of info for human readability. Implementations of FileInfo can call this from a String method. The output for a file named "hello.go", 100 bytes, mode 0o644, created January 1, 1970 at noon is

-rw-r--r-- 100 1970-01-01 12:00:00 hello.go

func Glob ¶

func Glob(fsys FS, 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 path.Match. The pattern may describe hierarchical names such as usr/*/bin/ed.

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

If fs implements GlobFS, Glob calls fs.Glob. Otherwise, Glob uses ReadDir to traverse the directory tree and look for matches for the pattern.

func ReadFile ¶

func ReadFile(fsys FS, name string) ([]byte, error)

ReadFile reads the named file from the file system fs and returns its contents. A successful call returns a nil error, not io.EOF. (Because ReadFile reads the whole file, the expected EOF from the final Read is not treated as an error to be reported.)

If fs implements ReadFileFS, ReadFile calls fs.ReadFile. Otherwise ReadFile calls fs.Open and uses Read and Close on the returned file.

func ValidPath ¶

func ValidPath(name string) bool

ValidPath reports whether the given path name is valid for use in a call to Open.

Path names passed to open are UTF-8-encoded, unrooted, slash-separated sequences of path elements, like “x/y/z”. Path names must not contain an element that is “.” or “..” or the empty string, except for the special case that the root directory is named “.”. Paths must not start or end with a slash: “/x” and “x/” are invalid.

Note that paths are slash-separated on all systems, even Windows. Paths containing other characters such as backslash and colon are accepted as valid, but those characters must never be interpreted by an FS implementation as path element separators.

func WalkDir ¶

func WalkDir(fsys FS, root string, fn 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 found in directories, but if root itself is a symbolic link, its target will be walked.

package main

import (
	"fmt"
	"io/fs"
	"log"
	"os"
)

func main() {
	root := "/usr/local/go/bin"
	fileSystem := os.DirFS(root)

	fs.WalkDir(fileSystem, ".", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			log.Fatal(err)
		}
		fmt.Println(path)
		return nil
	})
}

Output: