Walk a directory/Recursively
You are encouraged to solve this task according to the task description, using any language you may know.
Walk a given directory tree and print files matching a given pattern.
Note: This task is for recursive methods. These tasks should read an entire directory tree, not a single directory. For code examples that read a single directory, see Walk a directory/Non-recursively.
Note: Please be careful when running any code examples found here.
Ada
<lang ada>with Ada.Directories; use Ada.Directories; with Ada.Text_IO;
procedure Test_Directory_Walk is
procedure Walk (Name : String; Pattern : String) is
procedure Print (Item : Directory_Entry_Type) is
begin
Ada.Text_IO.Put_Line (Full_Name (Item));
end Print;
procedure Walk (Item : Directory_Entry_Type) is
begin
if Simple_Name (Item) /= "." and then Simple_Name (Item) /= ".." then
Walk (Full_Name (Item), Pattern);
end if;
exception
when Name_Error => null;
end Walk;
begin
Search (Name, Pattern, (others => True), Print'Access);
Search (Name, "", (Directory => True, others => False), Walk'Access);
end Walk;
begin
Walk (".", "*.adb");
end Test_Directory_Walk;</lang> The solution first enumerates files in a directory, that includes the subdirectories, if their names match the pattern. Then it steps down into each of the subdirectories. The pseudo directories . and .. are excluded. The behavior upon symbolic links depends on the OS and the implementation of the Ada.Directories package.
ALGOL 68
<lang algol68>INT match=0, no match=1, out of memory error=2, other error=3;
STRING slash = "/", pwd=".", parent="..";
PROC walk tree = (STRING path, PROC (STRING)VOID call back)VOID: (
[]STRING files = get directory(path);
FOR file index TO UPB files DO
STRING file = files[file index];
STRING path file = path+slash+file;
IF file is directory(path file) THEN
IF file NE pwd AND file NE parent THEN
walk tree(path file, call back)
FI
ELSE
call back(path file)
FI
OD
);
STRING re sort a68 = "[Ss]ort[^/]*[.]a68$";
PROC match sort a68 and print = (STRING path file)VOID:
IF grep in string(re sort a68, path file, NIL, NIL) = match THEN print((path file, new line)) FI;
walk tree(".", match sort a68 and print)</lang> Sample Output:
./Shell_sort_c.a68 ./Quick_sort.a68 ./Shell_sort.a68 ./Cocktail_Sort.a68 ./Selection_Sort.a68 ./Merge_sort.a68 ./tmp/test_sort.a68 ./Bobosort.a68 ./Sorting_an_Array_of_Integers.a68 ./Insertion_Sort.a68 ./Permutation_Sort.a68
AutoHotkey
Display all TMP files in Temp directory and its subdirectories. <lang autohotkey>Loop, %A_Temp%\*.tmp,,1
out .= A_LoopFileName "`n"
MsgBox,% out</lang>
Batch File
<lang dos>dir /a-d %1</lang>
If you wanted to apply some command to each item in a directory tree, then use /R on a FOR. For example, apply the ECHO command to every DLL file in C:\Windows\System32:
<lang dos>FOR /R C:\Windows\System32 %F IN (*.DLL) DO ECHO "%F"</lang>
BBC BASIC
<lang bbcbasic> directory$ = "C:\Windows\"
pattern$ = "*.chm"
PROClisttree(directory$, pattern$)
END
DEF PROClisttree(dir$, filter$)
LOCAL dir%, sh%, res%
DIM dir% LOCAL 317
IF RIGHT$(dir$) <> "\" IF RIGHT$(dir$) <> "/" dir$ += "\"
SYS "FindFirstFile", dir$ + filter$, dir% TO sh%
IF sh% <> -1 THEN
REPEAT
IF (!dir% AND 16) = 0 PRINT dir$ + $$(dir%+44)
SYS "FindNextFile", sh%, dir% TO res%
UNTIL res% = 0
SYS "FindClose", sh%
ENDIF
SYS "FindFirstFile", dir$ + "*", dir% TO sh%
IF sh% <> -1 THEN
REPEAT
IF (!dir% AND 16) IF dir%?44 <> &2E THEN
PROClisttree(dir$ + $$(dir%+44) + "\", filter$)
ENDIF
SYS "FindNextFile", sh%, dir% TO res%
UNTIL res% = 0
SYS "FindClose", sh%
ENDIF
ENDPROC</lang>
C
<lang C>#include <sys/types.h>
- include <sys/stat.h>
- include <unistd.h>
- include <dirent.h>
- include <regex.h>
- include <stdio.h>
- include <string.h>
- include <errno.h>
- include <err.h>
enum { WALK_OK = 0, WALK_BADPATTERN, WALK_NAMETOOLONG, WALK_BADIO, };
- define WS_NONE 0
- define WS_RECURSIVE (1 << 0)
- define WS_DEFAULT WS_RECURSIVE
- define WS_FOLLOWLINK (1 << 1) /* follow symlinks */
- define WS_DOTFILES (1 << 2) /* per unix convention, .file is hidden */
- define WS_MATCHDIRS (1 << 3) /* if pattern is used on dir names too */
int walk_recur(char *dname, regex_t *reg, int spec) { struct dirent *dent; DIR *dir; struct stat st; char fn[FILENAME_MAX]; int res = WALK_OK; int len = strlen(dname); if (len >= FILENAME_MAX - 1) return WALK_NAMETOOLONG;
strcpy(fn, dname); fn[len++] = '/';
if (!(dir = opendir(dname))) { warn("can't open %s", dname); return WALK_BADIO; }
errno = 0; while ((dent = readdir(dir))) { if (!(spec & WS_DOTFILES) && dent->d_name[0] == '.') continue; if (!strcmp(dent->d_name, ".") || !strcmp(dent->d_name, "..")) continue;
strncpy(fn + len, dent->d_name, FILENAME_MAX - len); if (lstat(fn, &st) == -1) { warn("Can't stat %s", fn); res = WALK_BADIO; continue; }
/* don't follow symlink unless told so */ if (S_ISLNK(st.st_mode) && !(spec & WS_FOLLOWLINK)) continue;
/* will be false for symlinked dirs */ if (S_ISDIR(st.st_mode)) { /* recursively follow dirs */ if ((spec & WS_RECURSIVE)) walk_recur(fn, reg, spec);
if (!(spec & WS_MATCHDIRS)) continue; }
/* pattern match */ if (!regexec(reg, fn, 0, 0, 0)) puts(fn); }
if (dir) closedir(dir); return res ? res : errno ? WALK_BADIO : WALK_OK; }
int walk_dir(char *dname, char *pattern, int spec) { regex_t r; int res; if (regcomp(&r, pattern, REG_EXTENDED | REG_NOSUB)) return WALK_BADPATTERN; res = walk_recur(dname, &r, spec); regfree(&r);
return res; }
int main() { int r = walk_dir(".", ".\\.c$", WS_DEFAULT|WS_MATCHDIRS); switch(r) { case WALK_OK: break; case WALK_BADIO: err(1, "IO error"); case WALK_BADPATTERN: err(1, "Bad pattern"); case WALK_NAMETOOLONG: err(1, "Filename too long"); default: err(1, "Unknown error?"); } return 0; }</lang>
With the fts(3) functions from 4.4BSD, this program can sort the files, and can also detect cycles (when a link puts a directory inside itself). This program makes a logical traversal that follows symbolic links to directories.
<lang c>#include <sys/types.h>
- include <err.h>
- include <errno.h>
- include <fnmatch.h>
- include <fts.h>
- include <string.h>
- include <stdio.h>
/* Compare files by name. */ int entcmp(const FTSENT **a, const FTSENT **b) { return strcmp((*a)->fts_name, (*b)->fts_name); }
/*
* Print all files in the directory tree that match the glob pattern.
* Example: pmatch("/usr/src", "*.c");
*/
void pmatch(char *dir, const char *pattern) { FTS *tree; FTSENT *f; char *argv[] = { dir, NULL };
/* * FTS_LOGICAL follows symbolic links, including links to other * directories. It detects cycles, so we never have an infinite * loop. FTS_NOSTAT is because we never use f->statp. It uses * our entcmp() to sort files by name. */ tree = fts_open(argv, FTS_LOGICAL | FTS_NOSTAT, entcmp); if (tree == NULL) err(1, "fts_open");
/* * Iterate files in tree. This iteration always skips * "." and ".." because we never use FTS_SEEDOT. */ while (f = fts_read(tree)) { switch (f->fts_info) { case FTS_DNR: /* Cannot read directory */ case FTS_ERR: /* Miscellaneous error */ case FTS_NS: /* stat() error */ /* Show error, then continue to next files. */ warn("%s", f->fts_path); continue; case FTS_DP: /* Ignore post-order visit to directory. */ continue; }
/* * Check if name matches pattern. If so, then print * path. This check uses FNM_PERIOD, so "*.c" will not * match ".invisible.c". */ if (fnmatch(pattern, f->fts_name, FNM_PERIOD) == 0) puts(f->fts_path);
/* * A cycle happens when a symbolic link (or perhaps a * hard link) puts a directory inside itself. Tell user * when this happens. */ if (f->fts_info == FTS_DC) warnx("%s: cycle in directory tree", f->fts_path); }
/* fts_read() sets errno = 0 unless it has error. */ if (errno != 0) err(1, "fts_read");
if (fts_close(tree) < 0) err(1, "fts_close"); }
int main() { pmatch(".", "*.c"); return 0; }</lang>
Windows
<lang c>#include <windows.h>
- include <stdio.h>
- include <stdlib.h>
- include <wchar.h>
/* Print "message: last Win32 error" to stderr. */ void oops(const wchar_t *message) { wchar_t *buf; DWORD error;
buf = NULL; error = GetLastError(); FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, error, 0, (wchar_t *)&buf, 0, NULL);
if (buf) { fwprintf(stderr, L"%ls: %ls", message, buf); LocalFree(buf); } else { /* FormatMessageW failed. */ fwprintf(stderr, L"%ls: unknown error 0x%x\n", message, error); } }
/*
* Print all files in a given directory tree that match a given wildcard * pattern. */
int main() { struct stack { wchar_t *path; size_t pathlen; size_t slashlen; HANDLE ffh; WIN32_FIND_DATAW ffd; struct stack *next; } *dir, dir0, *ndir; size_t patternlen; int argc; wchar_t **argv, *buf, c, *pattern;
/* MinGW never provides wmain(argc, argv). */ argv = CommandLineToArgvW(GetCommandLineW(), &argc); if (argv == NULL) { oops(L"CommandLineToArgvW"); exit(1); }
if (argc != 3) { fwprintf(stderr, L"usage: %ls dir pattern\n", argv[0]); exit(1); }
dir0.path = argv[1]; dir0.pathlen = wcslen(dir0.path); pattern = argv[2]; patternlen = wcslen(pattern);
if (patternlen == 0 || wcscmp(pattern, L".") == 0 || wcscmp(pattern, L"..") == 0 || wcschr(pattern, L'/') || wcschr(pattern, L'\\')) { fwprintf(stderr, L"%ls: invalid pattern\n", pattern); exit(1); }
/* * Must put backslash between path and pattern, unless * last character of path is slash or colon. * * 'dir' => 'dir\*' * 'dir\' => 'dir\*' * 'dir/' => 'dir/*' * 'c:' => 'c:*' * * 'c:*' and 'c:\*' are different files! */ c = dir0.path[dir0.pathlen - 1]; if (c == ':' || c == '/' || c == '\\') dir0.slashlen = dir0.pathlen; else dir0.slashlen = dir0.pathlen + 1;
/* Allocate space for path + backslash + pattern + \0. */ buf = calloc(dir0.slashlen + patternlen + 1, sizeof buf[0]); if (buf == NULL) { perror("calloc"); exit(1); } dir0.path = wmemcpy(buf, dir0.path, dir0.pathlen + 1);
dir0.ffh = INVALID_HANDLE_VALUE; dir0.next = NULL; dir = &dir0;
/* Loop for each directory in linked list. */ loop: while (dir) { /* * At first visit to directory: * Print the matching files. Then, begin to find * subdirectories. * * At later visit: * dir->ffh is the handle to find subdirectories. * Continue to find them. */ if (dir->ffh == INVALID_HANDLE_VALUE) { /* Append backslash + pattern + \0 to path. */ dir->path[dir->pathlen] = '\\'; wmemcpy(dir->path + dir->slashlen, pattern, patternlen + 1);
/* Find all files to match pattern. */ dir->ffh = FindFirstFileW(dir->path, &dir->ffd); if (dir->ffh == INVALID_HANDLE_VALUE) { /* Check if no files match pattern. */ if (GetLastError() == ERROR_FILE_NOT_FOUND) goto subdirs;
/* Bail out from other errors. */ dir->path[dir->pathlen] = '\0'; oops(dir->path); goto popdir; }
/* Remove pattern from path; keep backslash. */ dir->path[dir->slashlen] = '\0';
/* Print all files to match pattern. */ do { wprintf(L"%ls%ls\n", dir->path, dir->ffd.cFileName); } while (FindNextFileW(dir->ffh, &dir->ffd) != 0); if (GetLastError() != ERROR_NO_MORE_FILES) { dir->path[dir->pathlen] = '\0'; oops(dir->path); } FindClose(dir->ffh);
subdirs: /* Append * + \0 to path. */ dir->path[dir->slashlen] = '*'; dir->path[dir->slashlen + 1] = '\0';
/* Find first possible subdirectory. */ dir->ffh = FindFirstFileExW(dir->path, FindExInfoStandard, &dir->ffd, FindExSearchLimitToDirectories, NULL, 0); if (dir->ffh == INVALID_HANDLE_VALUE) { dir->path[dir->pathlen] = '\0'; oops(dir->path); goto popdir; } } else { /* Find next possible subdirectory. */ if (FindNextFileW(dir->ffh, &dir->ffd) == 0) goto closeffh; }
/* Enter subdirectories. */ do { const wchar_t *fn = dir->ffd.cFileName; const DWORD attr = dir->ffd.dwFileAttributes; size_t buflen, fnlen;
/* * Skip '.' and '..', because they are links to * the current and parent directories, so they * are not subdirectories. * * Skip any file that is not a directory. * * Skip all reparse points, because they might * be symbolic links. They might form a cycle, * with a directory inside itself. */ if (wcscmp(fn, L".") == 0 || wcscmp(fn, L"..") == 0 || (attr & FILE_ATTRIBUTE_DIRECTORY) == 0 || (attr & FILE_ATTRIBUTE_REPARSE_POINT)) continue;
ndir = malloc(sizeof *ndir); if (ndir == NULL) { perror("malloc"); exit(1); }
/* * Allocate space for path + backslash + * fn + backslash + pattern + \0. */ fnlen = wcslen(fn); buflen = dir->slashlen + fnlen + patternlen + 2; buf = calloc(buflen, sizeof buf[0]); if (buf == NULL) { perror("malloc"); exit(1); }
/* Copy path + backslash + fn + \0. */ wmemcpy(buf, dir->path, dir->slashlen); wmemcpy(buf + dir->slashlen, fn, fnlen + 1);
/* Push dir to list. Enter dir. */ ndir->path = buf; ndir->pathlen = dir->slashlen + fnlen; ndir->slashlen = ndir->pathlen + 1; ndir->ffh = INVALID_HANDLE_VALUE; ndir->next = dir; dir = ndir; goto loop; /* Continue outer loop. */ } while (FindNextFileW(dir->ffh, &dir->ffd) != 0); closeffh: if (GetLastError() != ERROR_NO_MORE_FILES) { dir->path[dir->pathlen] = '\0'; oops(dir->path); } FindClose(dir->ffh);
popdir: /* Pop dir from list, free dir, but never free dir0. */ free(dir->path); if (ndir = dir->next) free(dir); dir = ndir; }
return 0; }</lang>
Common Lisp
This example uses the CL-FAD library to achieve compatibility where the ANSI CL standard leaves ambiguities about pathnames.
<lang lisp>(defun mapc-directory-tree (fn directory)
(dolist (entry (cl-fad:list-directory directory))
(when (cl-fad:directory-pathname-p entry)
(mapc-directory-tree fn entry))
(funcall fn entry)))</lang>
<lang lisp>CL-USER> (mapc-directory-tree (lambda (x)
(when (equal (pathname-type x) "lisp")
(write-line (namestring x))))
"lang/")
/home/sthalik/lang/lisp/.#bitmap.lisp /home/sthalik/lang/lisp/avg.lisp /home/sthalik/lang/lisp/bitmap.lisp /home/sthalik/lang/lisp/box-muller.lisp /home/sthalik/lang/lisp/displaced-subseq.lisp [...]</lang>
C#
<lang csharp> using System.IO;
namespace ConsoleApplication1 {
class Program
{
static void Main(string[] args)
{
DirectoryInfo tDir = new DirectoryInfo(@"C:\");
string Pattern = "a";
TraverseDirs(tDir, Pattern);
Console.Read();
}
private static void TraverseDirs(DirectoryInfo dir, string Pattern)
{
// Subdirs
try // Avoid errors such as "Access Denied"
{
foreach (DirectoryInfo iInfo in dir.GetDirectories())
{
if (iInfo.Name.StartsWith(Pattern))
Console.WriteLine("Found dir: " + iInfo.FullName);
TraverseDirs(iInfo, Pattern);
}
}
catch (Exception)
{
}
// Subfiles
try // Avoid errors such as "Access Denied"
{
foreach (FileInfo iInfo in dir.GetFiles())
{
if (iInfo.Name.StartsWith(Pattern))
Console.WriteLine("Found file: " + iInfo.FullName);
}
}
catch (Exception)
{
}
}
}
}</lang>
C++
<lang cpp>#include "boost/filesystem.hpp"
- include "boost/regex.hpp"
- include <iostream>
using namespace boost::filesystem;
int main() {
path current_dir("."); //
boost::regex pattern("a.*"); // list all files starting with a
for (recursive_directory_iterator iter(current_dir), end;
iter != end;
++iter)
{
std::string name = iter->path().leaf();
if (regex_match(name, pattern))
std::cout << iter->path() << "\n";
}
}</lang>
Clojure
The standard function file-seq does a tree walk. <lang clojure>(import '[java.io File])
(defn walk [dirpath pattern]
(doseq [file (-> dirpath File. file-seq)]
(if (re-matches pattern (.getName file))
(println (.getPath file)))))
(walk "src" #".*\.clj")</lang>
D
module std.file provides different walk directory functions (listdir).
This one recursively walks the directory, which can either match by regular expression or unix shell style pattern.
<lang d>import std.stdio;
import std.file;
import std.regexp;
void main(string[] args) {
auto path = args.length > 1 ? args[1] : "." ; // default current auto pattern = args.length > 2 ? args[2] : "*.*"; // default all file bool useRegExp = (args.length > 3 && args[3] == "-re") ; // pattern matching method
if (args.length > 3 && args[3] == "-re")
// use Regular Expression
foreach (d; listdir(path, RegExp(pattern)))
writefln(d);
else
// use unix shell style pattern matching
foreach (d; listdir(path, pattern))
writefln(d);
}</lang>
This one does not itself walk into a sub directory, but can be recursive by a callback delegate function. <lang d>import std.stdio; import std.file; import std.regexp; import std.path ;
void main(string[] args) {
auto path = args.length > 1 ? args[1] : "." ; // default current auto pattern = args.length > 2 ? args[2] : "*.*"; // default all file bool useRegExp = (args.length > 3 && args[3] == "-re") ; // pattern matching method bool recursive = (args.length <= 4 || args[4] != "-nr") ; // recursive?
bool matchNPrint(DirEntry* de) {
bool bPrint = false ;
if(!de.isdir) {
if(useRegExp){
if(search(de.name, pattern)) // this _search_ from regexp module
writefln(de.name) ;
}else{
if(fnmatch(de.name, pattern)) // this _fnmatch_ from path module
writefln(de.name) ;
}
} else
if(recursive)
listdir(de.name, &matchNPrint) ; // recursive sub dir
return true ; // continue
}
listdir(path, &matchNPrint) ;
}</lang>
E
<lang e>def walkTree(directory, pattern) {
for name => file in directory {
if (name =~ rx`.*$pattern.*`) {
println(file.getPath())
}
if (file.isDirectory()) {
walkTree(file, pattern)
}
}
}</lang>
Example:
<lang e>? walkTree(<file:/usr/share/man>, "rmdir") /usr/share/man/man1/rmdir.1 /usr/share/man/man2/rmdir.2</lang>
F#
This code is tail-recursive and lazy. <lang fsharp> open System.IO
let rec getAllFiles dir pattern =
seq { yield! Directory.EnumerateFiles(dir, pattern)
for d in Directory.EnumerateDirectories(dir) do
yield! getAllFiles d pattern }
getAllFiles "c:\\temp" "*.xml" |> Seq.iter (printfn "%s") </lang>
Factor
<lang factor>USE: io.directories.search
"." t [
dup ".factor" tail? [ print ] [ drop ] if
] each-file</lang>
Forth
Todo: track the full path and print it on matching files.
<lang forth>defer ls-filter
- dots? ( name len -- ? )
dup 1 = if drop c@ [char] . = else 2 = if dup c@ [char] . = swap 1+ c@ [char] . = and else drop false then then ;
- ls-r ( dir len -- )
open-dir if drop exit then ( dirid)
begin
dup pad 256 rot read-dir throw
while
pad over dots? 0= if \ ignore current and parent dirs
pad over recurse
pad over ls-filter if
cr pad swap type
else drop then
else drop then
repeat
drop close-dir throw ;
- c-file? ( str len -- ? )
dup 3 < if 2drop false exit then + 1- dup c@ 32 or dup [char] c <> swap [char] h <> and if drop false exit then 1- dup c@ [char] . <> if drop false exit then drop true ;
' c-file? is ls-filter
s" ." ls-r</lang>
GAP
<lang gap>Walk := function(name, op) local dir, file, e; dir := Directory(name); for e in SortedList(DirectoryContents(name)) do file := Filename(dir, e); if IsDirectoryPath(file) then if not (e in [".", ".."]) then Walk(file, op); fi; else op(file); fi; od; end;
- This will print filenames
Walk(".", Display);</lang>
Go
<lang go>package main
import (
"fmt" "path/filepath" "os"
)
type MyVisitor struct{} // a type to satisfy filepath.Visitor interface
func (MyVisitor) VisitDir(string, *os.FileInfo) bool {
return true
}
func (MyVisitor) VisitFile(fp string, _ *os.FileInfo) {
if filepath.Ext(fp) == ".mp3" {
fmt.Println(fp)
}
}
func main() {
filepath.Walk("/", MyVisitor{}, nil)
}</lang>
Groovy
Print all text files in the current directory tree <lang groovy>new File('.').eachFileRecurse {
if (it.name =~ /.*\.txt/) println it;
}</lang>
GUISS
Here we list all files that match the pattern m*.txt in "My Documents" and all of its subfolders:
<lang guiss>Start,Find,Files and Folders,Dropdown: Look in>My Documents, Inputbox: filename>m*.txt,Button:Search</lang>
Haskell
<lang haskell>import System.Environment import System.Directory import System.FilePath.Find
search pat dir =
find always (fileName ~~? pat) dir
main = do [pat] <- getArgs
dir <- getCurrentDirectory
files <- search pat dir
mapM_ putStrLn files</lang>
IDL
<lang idl>result = file_search( directory, '*.txt', count=cc )</lang>
This will descend down the directory/ies in the variable "directory" (which can be an array) returning an array of strings with the names of the files matching "*.txt" and placing the total number of matches into the variable "cc"
Icon and Unicon
Icon
Icon doesn't support 'stat' or 'open' of a directory; however, information can be obtained by use of the system function to access command line.
Unicon
<lang Unicon>procedure main() every write(!getdirs(".")) # writes out all directories from the current directory down end
procedure getdirs(s) #: return a list of directories beneath the directory 's' local D,d,f
if ( stat(s).mode ? ="d" ) & ( d := open(s) ) then {
D := [s]
while f := read(d) do
if not ( ".." ? =f ) then # skip . and ..
D |||:= getdirs(s || "/" ||f)
close(d)
return D
}
end</lang>
J
<lang j>require 'dir' >{."1 dirtree '*.html'</lang>
The verb dirtree returns a file listing of a directory tree as a boxed matrix with file names in the first column. The primitives >{."1 will return the unboxed contents of the first column.
'*.html' can be replaced by another pattern, of course.
Java
Done using no pattern. But with end string comparison which gave better results.
<lang java>import java.io.File; public class MainEntry {
public static void main(String[] args) {
walkin(new File("/home/user")); //Replace this with a suitable directory
}
/**
* Recursive function to descend into the directory tree and find all the files
* that end with ".mp3"
* @param dir A file object defining the top directory
**/
public static void walkin(File dir) {
String pattern = ".mp3";
File listFile[] = dir.listFiles();
if(listFile != null) {
for(int i=0; i<listFile.length; i++) {
if(listFile[i].isDirectory()) {
walkin(listFile[i]);
} else {
if(listFile[i].getName().endsWith(pattern)) {
System.out.println(listFile[i].getPath());
}
}
}
}
}
}</lang>
JavaScript
<lang javascript>var fso = new ActiveXObject("Scripting.FileSystemObject");
function walkDirectoryTree(folder, folder_name, re_pattern) {
WScript.Echo("Files in " + folder_name + " matching '" + re_pattern + "':");
walkDirectoryFilter(folder.files, re_pattern);
var subfolders = folder.SubFolders;
WScript.Echo("Folders in " + folder_name + " matching '" + re_pattern + "':");
walkDirectoryFilter(subfolders, re_pattern);
WScript.Echo();
var en = new Enumerator(subfolders);
while (! en.atEnd()) {
var subfolder = en.item();
walkDirectoryTree(subfolder, folder_name + "/" + subfolder.name, re_pattern);
en.moveNext();
}
}
function walkDirectoryFilter(items, re_pattern) {
var e = new Enumerator(items);
while (! e.atEnd()) {
var item = e.item();
if (item.name.match(re_pattern))
WScript.Echo(item.name);
e.moveNext();
}
}
walkDirectoryTree(dir, dir.name, '\\.txt$');</lang>
Mathematica
The built-in function FileNames does exactly this: <lang Mathematica>FileNames[] lists all files in the current working directory. FileNames[form] lists all files in the current working directory whose names match the string pattern form. FileNames[{form1,form2,...}] lists all files whose names match any of the form_i. FileNames[forms,{dir1,dir2,...}] lists files with names matching forms in any of the directories dir_i. FileNames[forms,dirs,n] includes files that are in subdirectories up to n levels down.</lang> Examples (find all files in current directory, find all png files in root directory, find all files on the hard drive): <lang Mathematica>FileNames["*"] FileNames["*.png", $RootDirectory] FileNames["*", {"*"}, Infinity]</lang> the result can be printed with Print /@ FileNames[....]
MAXScript
<lang maxscript>fn walkDir dir pattern = (
dirArr = GetDirectories (dir + "\\*")
for d in dirArr do
(
join dirArr (getDirectories (d + "\\*"))
)
append dirArr (dir + "\\") -- Need to include the original top level directory
for f in dirArr do
(
print (getFiles (f + pattern))
)
)
walkDir "C:" "*.txt"</lang>
Objective-C
<lang objc>NSString *dir = NSHomeDirectory(); NSDirectoryEnumerator *de = [[NSFileManager defaultManager] enumeratorAtPath:dir];
NSString *file; while ((file = [de nextObject]))
if ([[file pathExtension] isEqualToString:@"mp3"]) NSLog(@"%@", file);</lang>
OCaml
<lang ocaml>#!/usr/bin/env ocaml
- load "unix.cma"
- load "str.cma"
open Unix
let walk_directory_tree dir pattern =
let select str = Str.string_match (Str.regexp pattern) str 0 in
let rec walk acc = function
| [] -> (acc)
| dir::tail ->
let contents = Array.to_list (Sys.readdir dir) in
let contents = List.rev_map (Filename.concat dir) contents in
let dirs, files =
List.fold_left (fun (dirs,files) f ->
match (stat f).st_kind with
| S_REG -> (dirs, f::files) (* Regular file *)
| S_DIR -> (f::dirs, files) (* Directory *)
| _ -> (dirs, files)
) ([],[]) contents
in
let matched = List.filter (select) files in
walk (matched @ acc) (dirs @ tail)
in
walk [] [dir]
let () =
let results = walk_directory_tree "/usr/local/lib/ocaml" ".*\\.cma" in List.iter print_endline results;
- </lang>
Oz
<lang oz>declare
[Path] = {Module.link ['x-oz://system/os/Path.ozf']}
[Regex] = {Module.link ['x-oz://contrib/regex']}
proc {WalkDirTree Root Pattern Proc}
proc {Walk R}
Entries = {Path.readdir R}
Files = {Filter Entries Path.isFile}
MatchingFiles = {Filter Files fun {$ File} {Regex.search Pattern File} \= false end}
Subdirs = {Filter Entries Path.isDir}
in
{ForAll MatchingFiles Proc}
{ForAll Subdirs Walk}
end
in
{Walk Root}
end
in
{WalkDirTree "." ".*\\.oz$" System.showInfo}</lang>
Perl
<lang perl>use File::Find qw(find); my $dir = '.'; my $pattern = 'foo'; find sub {print $File::Find::name if /$pattern/}, $dir;</lang>
Perl 6
Uses File::Find from File-Tools
<lang perl6>use File::Find;
.say for find(dir => '.').grep(/foo/);</lang>
PHP
<lang PHP>function findFiles($dir = '.', $pattern = '/./'){
$prefix = $dir . '/';
$dir = dir($dir);
while (false !== ($file = $dir->read())){
if ($file === '.' || $file === '..') continue;
$file = $prefix . $file;
if (is_dir($file)) findFiles($file, $pattern);
if (preg_match($pattern, $file)){
echo $file . "\n";
}
}
} findFiles('./foo', '/\.bar$/');</lang>
This implementation uses Perl compatible regular expressions to match the whole path of the file
PHP BFS (Breadth First Search)
<lang PHP>/* This script performs a BFS search with recursion protection it is often faster to search using this method across a filesystem due to a few reasons:
* filesystem is accessed in native node order * a recursive function is not required allowing infinate depth * multiple directory handles are not required * the file being searched for is often not that deep in the fs
This method also leverages PHP array hashing to speed up loop detection while minimizing the amount of RAM used to track the search history.
-Geoffrey McRae Released as open license for any use.
- /
if ($_SERVER['argc'] < 3) { printf( "\n" . "Usage: %s (path) (search) [stop]\n" . " path the path to search\n" . " search the filename to search for\n" . " stop stop when file found, default 1\n" . "\n" , $_SERVER['argv'][0]); exit(1); }
$path = $_SERVER['argv'][1]; $search = $_SERVER['argv'][2]; if ($_SERVER['argc'] > 3) $stop = $_SERVER['argv'][3] == 1; else $stop = true;
/* get the absolute path and ensure it has a trailing slash */ $path = realpath($path); if (substr($path, -1) !== DIRECTORY_SEPARATOR) $path .= DIRECTORY_SEPARATOR;
$queue = array($path => 1); $done = array(); $index = 0; while(!empty($queue)) { /* get one element from the queue */ foreach($queue as $path => $unused) { unset($queue[$path]); $done[$path] = null; break; } unset($unused);
$dh = @opendir($path); if (!$dh) continue; while(($filename = readdir($dh)) !== false) { /* dont recurse back up levels */ if ($filename == '.' || $filename == '..') continue;
/* check if the filename matches the search term */ if ($filename == $search) { echo "$path$filename\n"; if ($stop) break 2; }
/* get the full path */ $filename = $path . $filename;
/* resolve symlinks to their real path */ if (is_link($filename)) $filename = realpath($filename);
/* queue directories for later search */ if (is_dir($filename)) { /* ensure the path has a trailing slash */ if (substr($filename, -1) !== DIRECTORY_SEPARATOR) $filename .= DIRECTORY_SEPARATOR;
/* check if we have already queued this path, or have done it */ if (array_key_exists($filename, $queue) || array_key_exists($filename, $done)) continue;
/* queue the file */ $queue[$filename] = null; } } closedir($dh); } </lang>
PicoLisp
<lang PicoLisp>(let Dir "."
(recur (Dir)
(for F (dir Dir)
(let Path (pack Dir "/" F)
(cond
((=T (car (info Path))) # Is a subdirectory?
(recurse Path) ) # Yes: Recurse
((match '`(chop "s@.l") (chop F)) # Matches 's*.l'?
(println Path) ) ) ) ) ) ) # Yes: Print it</lang>
Output:
"./src64/sym.l" "./src64/subr.l" ...
Pop11
Built-in procedure sys_file_match searches directories or directory trees using shell-like patterns (three dots indicate search for subdirectory tree). <lang pop11>lvars repp, fil;
- create path repeater
sys_file_match('.../*.p', , false, 0) -> repp;
- iterate over paths
while (repp() ->> fil) /= termin do
;;; print the path
printf(fil, '%s\n');
endwhile;</lang>
PowerShell
In PowerShell the Get-ChildItem cmdlet allows for recursive filtering on file names with simple wildcards:
<lang powershell>Get-ChildItem -Recurse -Include *.mp3</lang>
For more complex filtering criteria the result of Get-ChildItem can be piped into the Where-Object cmdlet:
<lang powershell>Get-ChildItem -Recurse |
Where-Object { $_.Name -match 'foo[0-9]' -and $_.Length -gt 5MB }</lang>
To perform an action on every matching file the results can be piped into the ForEach-Object cmdlet:
<lang powershell>Get-ChildItem -Recurse |
Where-Object { $_.Name -match 'foo[0-9]' } |
ForEach-Object { ... }</lang>
Note: To include only files instead of directories too each of the above needs an additionalWhere-Object filter:
<lang powershell>| Where-Object { !$_.PSIsContainer }</lang>
PureBasic
<lang PureBasic>Procedure.s WalkRecursive(dir,path.s,Pattern.s="\.txt$")
Static RegularExpression
If Not RegularExpression
RegularExpression=CreateRegularExpression(#PB_Any,Pattern)
EndIf
While NextDirectoryEntry(dir)
If DirectoryEntryType(dir)=#PB_DirectoryEntry_Directory
If DirectoryEntryName(dir)<>"." And DirectoryEntryName(dir)<>".."
If ExamineDirectory(dir+1,path+DirectoryEntryName(dir),"")
WalkRecursive(dir+1,path+DirectoryEntryName(dir)+"\",Pattern)
FinishDirectory(dir+1)
Else
Debug "Error in "+path+DirectoryEntryName(dir)
EndIf
EndIf
Else ; e.g. #PB_DirectoryEntry_File
If MatchRegularExpression(RegularExpression,DirectoryEntryName(dir))
Debug DirectoryEntryName(dir)
EndIf
EndIf
Wend
EndProcedure</lang> <lang PureBasic>;- Implementation; Find all .log-files in the C:\Windows tree ExamineDirectory(1,"C:\WINDOWS\","") WalkRecursive(1,"C:\WINDOWS\","\.log$") FinishDirectory(1)</lang>
Python
This uses the standard os.walk() module function to walk a directory tree, and the fnmatch module for matching file names.
<lang python>import fnmatch import os
rootPath = '/' pattern = '*.mp3'
for root, dirs, files in os.walk(rootPath):
for filename in fnmatch.filter(files, pattern):
print( os.path.join(root, filename))</lang>
A more strictly comparable port of this 2.3+ code to earlier versions of Python would be:
<lang python>from fnmatch import fnmatch import os, os.path
def print_fnmatches(pattern, dir, files):
for filename in files:
if fnmatch(filename, pattern):
print os.path.join(dir, filename)
os.path.walk('/', print_fnmatches, '*.mp3')</lang>
The old os.path.walk function was a challenge for many to use because of the need to pass a function into the walk, and any arguments to that function through to it ... as shown. It's sometimes useful to pass mutable objects (lists, dictionaries, or instances of user-defined classes) to the inner function ... for example, to collect all the matching files for later processing.
Of course the function being passed down through os.path.walk() can also be an instance of an object which maintains it's own data collections. Any matching criteria can be set as attributes of that object in advance and methods of that object can be called upon for later processing as well. That would the an object oriented approach which would obviate the need for the "arguments" to be passed through os.path.walk() at all.
(Note: This uses a non-standard replacement to the os.path module)
<lang python>from path import path
rootPath = '/' pattern = '*.mp3'
d = path(rootPath) for f in d.walkfiles(pattern):
print f</lang>
R
<lang R>dir("/bar/foo", "mp3",recursive=T)</lang>
REALbasic
<lang vb> Sub printFiles(parentDir As FolderItem, pattern As String)
For i As Integer = 1 To parentDir.Count
If parentDir.Item(i).Directory Then
printFiles(parentDir.Item(i), pattern)
Else
Dim rg as New RegEx
Dim myMatch as RegExMatch
rg.SearchPattern = pattern
myMatch = rg.search(parentDir.Item(i).Name)
If myMatch <> Nil Then Print(parentDir.Item(i).AbsolutePath)
End If
Next
End Sub </lang>
Accepts a FolderItem object and a Regex pattern as a string: <lang vb>
Dim f As FolderItem = GetFolderItem("C:\Windows\system32")
Dim pattern As String = "((?:[a-z][a-z]+))(\.)(dll)" //all file names ending in .dll
printFiles(f, pattern)</lang>
Ruby
Using the Find core Module
<lang ruby>require 'find'
Find.find('/your/path') do |f|
# print file and path to screen if filename ends in ".mp3" puts f if f.match(/\.mp3\Z/)
end </lang>
Scala
This is not implemented in the Scala library. Here is a possible solution, building on class java.io.File and on scala language and library iteration facilities
<lang scala>package io.utils
import java.io.File
/** A wrapper around file, allowing iteration either on direct children
or on directory tree */
class RichFile(file: File) {
def children = new Iterable[File] {
def elements =
if (file.isDirectory) file.listFiles.elements else Iterator.empty;
}
def andTree : Iterable[File] = ( Seq(file) ++ children.flatMap(child => new RichFile(child).andTree))
}
/** implicitely enrich java.io.File with methods of RichFile */ object RichFile {
implicit def toRichFile(file: File) = new RichFile(file)
}</lang>
Class RichFile gets a java.io.File in constructor. Its two methods return Iterables on items of type File. children allow iterations on the direct children (empty if file is not a directory). andTree contains a file and all files below, as a concatenation (++) of a sequence which contains only a file (Seq.single) and actual descendants. The method flatMap in Iterable takes a function argument which associates each item (child) to another Iterable (andTree called recursively on that child) and returns the concatenation of those iterables.
The purpose of the object RichFile is to publish the implicit method toRichFile. When this method is available in scope (after import RichFile.toRichFile or import RichFile._), it is called behind the scene when a method of class RichFile is called on an instance of type File : with f of type File, code f.children (resp. f.andTree) becomes toRichFile(f).children (resp. toRichFile(f).andTree). It is as if class File had been added the methods of class RichFile.
Using it : <lang scala>package test.io.utils
import io.utils.RichFile._ // this makes implicit toRichFile active import java.io.File
object Test extends Application {
val root = new File("/home/user")
for(f <- root.andTree) Console.println(f)
// filtering comes for free
for(f <- root.andTree; if f.getName.endsWith(".mp3")) Console.println(f)
}</lang>
Scheme
Varies slightly depending on the implementation of scheme.
<lang scheme> (use posix) (use files) (use srfi-13)
(define (walk FN PATH)
(for-each (lambda (ENTRY) (cond ((not (null? ENTRY))
(let ((MYPATH (make-pathname PATH ENTRY)))
(cond ((directory-exists? MYPATH) (walk FN MYPATH) ))
(FN MYPATH) )))) (directory PATH #t) ))
(walk (lambda (X) (cond ((string-suffix? ".scm" X) (display X)(newline) ))) "/home/user/") </lang>
See also: (find-files ...) function in the posix module.
<lang scheme> (use file.util) (use srfi-13)
(define (walk FN PATH)
(for-each (lambda (ENTRY) (cond ((not (null? ENTRY))
(let ((MYPATH ENTRY))
(cond ((file-is-directory? MYPATH) (walk FN MYPATH) ))
(FN MYPATH) )))) (directory-list PATH :add-path? #t :children? #t ) ))
(walk (lambda (X) (cond ((string-suffix? ".scm" X) (display X)(newline) ))) "/home/user/") </lang> See also: (find-file-in-paths ...) function in the file.util module.
<lang scheme>
- lang scheme
(require srfi/13)
(define (walk FN PATH)
(for-each (lambda (ENTRY) (cond ((not (null? ENTRY))
(let ((MYPATH (build-path PATH ENTRY)))
(cond ((directory-exists? MYPATH) (walk FN MYPATH) ))
(FN MYPATH) )))) (directory-list PATH)))
(walk (lambda (X) (cond ((string-suffix? ".scm" (path->string X)) (display X)(newline) ))) "/home/user/") </lang> See also: (find-files ...) function in the file module.
Sample output: <lang scheme> /home/user/one.scm /home/user/lang/two.scm [...] </lang>
Smalltalk
<lang smalltalk>Directory extend [
wholeContent: aPattern do: twoBlock [
self wholeContent: aPattern withLevel: 0 do: twoBlock.
]
wholeContent: aPattern withLevel: l do: twoBlock [
|cont|
cont := (self contents) asSortedCollection.
cont remove: '.'; remove: '..'.
cont
do: [ :n | |fn ps|
ps := (Directory pathSeparator) asString.
fn := (self name), ps, n.
((File name: fn) isDirectory)
ifTrue: [
twoBlock value: (n, ps) value: l.
(Directory name: fn) wholeContent: aPattern withLevel: (l+1) do: twoBlock.
]
ifFalse: [
( n =~ aPattern )
ifMatched: [ :m |
twoBlock value: n value: l
]
]
]
]
].</lang>
<lang smalltalk>|d| d := Directory name: '.'. d wholeContent: '\.st$' do: [ :f :l |
0 to: l do: [ :i | (Character tab) display ]. f displayNl
].</lang>
Tcl
<lang tcl>proc walkin {fromDir pattern} {
foreach fname [glob -nocomplain -directory $fromDir *] {
if {[file isdirectory $fname]} {
walkin $fname $pattern
} elseif {[string match $pattern [file tail $fname]]} {
puts [file normalize $fname]
}
}
}
- replace directory with something appropriate
walkin /home/user *.mp3</lang>
Visual Basic .NET
This uses the OS pattern matching
<lang vbnet>Sub walkTree(ByVal directory As IO.DirectoryInfo, ByVal pattern As String)
For Each file In directory.GetFiles(pattern)
Console.WriteLine(file.FullName)
Next
For Each subDir In directory.GetDirectories
walkTree(subDir, pattern)
Next
End Sub</lang>
UNIX Shell
The "find" command gives a one-line solution for simple patterns:
<lang bash>find . -name '*.txt' -type f </lang>
"find" can also be used to find files matching more complex patterns as illustrated in the section on Unix Pipes below.
Using "bash" version 4 or later, you can use "globstar" or "dotglob", depending on whether you want hidden directories to be searched:
<lang bash>#! /bin/bash
- Warning: globstar excludes hidden directories.
- Turn on recursive globbing (in this script) or exit if the option is not supported:
shopt -s globstar || exit
for f in ** do
if "$f" =~ \.txt$ ; then echo "$f" fi
done
</lang>
Here is a solution that does not use "find".
<lang bash>#! /bin/bash
indent_print() {
for((i=0; i < $1; i++)); do
echo -ne "\t"
done echo "$2"
}
walk_tree() {
local oldifs bn lev pr pmat if $# -lt 3 ; then
if $# -lt 2 ; then pmat=".*" else pmat="$2" fi walk_tree "$1" "$pmat" 0 return
fi lev=$3 [ -d "$1" ] || return oldifs=$IFS IFS="
"
for el in $1/*; do
bn=$(basename "$el") if -d "$el" ; then indent_print $lev "$bn/" pr=$( walk_tree "$el" "$2" $(( lev + 1)) ) echo "$pr" else if "$bn" =~ $2 ; then indent_print $lev "$bn" fi fi
done IFS=$oldifs
}
walk_tree "$1" "\.sh$"</lang>
A simplified version that gives the same output:
<lang bash>#! /usr/bin/env bash
walk_tree() { ls "$1" | while IFS= read i; do if [ -d "$1/$i" ]; then echo "$i/" walk_tree "$1/$i" "$2" | sed -r 's/^/\t/' else echo "$i" | grep -E "$2" fi done }
walk_tree "$1" "\.sh$"</lang>
UnixPipes
As illustrated above, the "find" command can be used with the -name option to match simple patterns. To find files matching more complex patterns, the results of "find" can be piped, e.g.
<lang bash>find . -type f | egrep '\.txt$|\.TXT$'</lang>
One way to run a command against each file that is found is to use "xargs", but if there is any possibility that a filename contains a space or tab character, then the following model should be used:
<lang bash> find . -type f -name "*.txt" -print0 | xargs -0 fgrep sometext</lang>
Zsh
Zsh has recursive globbing. The GLOB_DOTS option allows files beginning with a period to be matched. <lang zsh>setopt GLOB_DOTS print -l -- **/*.txt</lang> GLOB_DOTS can be set temporarily with the 'D' modifier. <lang zsh>print -l -- **/*.txt(D)</lang>
- Programming Tasks
- File System Operations
- Recursion
- MUMPS/Omit
- Ada
- ALGOL 68
- AutoHotkey
- Batch File
- BBC BASIC
- C
- POSIX
- BSD libc
- Win32
- Common Lisp
- CL-FAD
- C sharp
- C++
- Boost
- Clojure
- D
- E
- F Sharp
- Factor
- Forth
- GAP
- Go
- Groovy
- GUISS
- Haskell
- IDL
- Icon
- Unicon
- J
- Java
- JavaScript
- Mathematica
- MAXScript
- Objective-C
- OCaml
- Oz
- Perl
- Perl 6
- PHP
- PHP BFS (Breadth First Search)
- PicoLisp
- Pop11
- PowerShell
- PureBasic
- Python
- Path
- R
- REALbasic
- Ruby
- Scala
- Scheme
- Smalltalk
- Tcl
- Visual Basic .NET
- UNIX Shell
- UnixPipes
- Zsh
- Befunge/Omit
- M4/Omit
- PARI/GP/Omit
- Retro/Omit
- TI-89 BASIC/Omit
- Unlambda/Omit
- ZX Spectrum Basic/Omit