Walk Directory

From Rosetta Code

Walk a given directory and print the names of files matching a given pattern.

Note: This task is for non-recursive methods. These tasks should read a single directory, not an entire directory tree. For code examples that read entire directory trees, see Walk Directory Tree

Note: Please be careful when running any code presented here.

Contents 1 Ada 2 C 3 ColdFusion 4 Common Lisp 5 D 6 E 7 Forth 8 Groovy 9 Haskell 10 IDL 11 MAXScript 12 OCaml 13 Perl 14 PHP 15 Pop11 16 Python 17 Raven 18 Ruby 19 Tcl 20 Toka 21 Visual Basic .NET 22 UnixPipes

[edit] Ada

Works with: GCC version 4.12

 
 with Ada.Directories; use Ada.Directories;
 with Ada.Text_IO; use Ada.Text_IO;
 
 procedure Walk_Directory
             (Directory : in String := ".";
              Pattern   : in String := "") -- empty pattern = all file names/subdirectory names
 is
    Search  : Search_Type;
    Dir_Ent : Directory_Entry_Type;
 begin
    Start_Search (Search, Directory, Pattern);
 
    while More_Entries (Search) loop
       Get_Next_Entry (Search, Dir_Ent);
       Put_Line (Simple_Name (Dir_Ent));
    end loop;
 
    End_Search (Search);
 end Walk_Directory;
 

[edit] C

Works with: gcc version 4.0.1

Platform: BSD

In this example, the pattern is a POSIX extended regular expression.

#include <sys/types.h>
#include <dirent.h>
#include <regex.h>
#include <stdio.h>

void walker(const char *dir, const char *pattern)
{
    struct dirent *entry;
    regex_t reg;
    DIR *d; 

    if (regcomp(&reg, pattern, REG_EXTENDED | REG_NOSUB))
        return;
    if (!(d = opendir(dir)))
        return;
    while (entry = readdir(d))
        if (!regexec(&reg, entry->d_name, 0, NULL, 0))
            puts(entry->d_name);
    closedir(d);
}

int main()
{
    walker(".", ".\\.c$");
    return 0;
}

[edit] ColdFusion

This example display all files and directories directly under C:\temp that end with .html

<cfdirectory action="list" directory="C:\temp" filter="*.html" name="dirListing">
<cfoutput query="dirListing">
  #dirListing.name# (#dirListing.type#)<br>
</cfoutput>

[edit] Common Lisp

(defun walk-directory (directory pattern)
  (directory (merge-pathnames pattern directory)))

Uses the filename pattern syntax provided by the CL implementation.

[edit] D

See also the D code at Walk Directory Tree.

import std.stdio;
import std.file;
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 matchNPrint(DirEntry* de){
    if(!de.isdir && fnmatch(de.name, pattern))
      writefln(de.name) ; 
    return true ; // continue
  }       

  listdir(path, &matchNPrint) ;
 }

[edit] E

def walkDirectory(directory, pattern) {
  for name => file ? (name =~ rx`.*$pattern.*`) in directory {
    println(name)
  }
}

Example:

? walkDirectory(<file:~>, "bash_")
.bash_history
.bash_profile
.bash_profile~

[edit] Forth

Works with: gforth version 0.6.2

Gforth's directory walking functions are tied to the POSIX dirent functions, used by the C langauge entry above. Forth doesn't have regex support, so a simple filter function is used instead.

defer ls-filter ( name len -- ? )
: ls-all  2drop true ;
: ls-visible  drop c@ [char] . <> ;

: ls ( dir len -- )
  open-dir throw  ( dirid )
  begin
    dup pad 256 rot read-dir throw
  while
    pad over ls-filter if
      cr pad swap type
    else drop then
  repeat
  drop close-dir throw ;

\ only show C language source and header files (*.c *.h)
: c-file? ( str len -- ? )
  dup 3 < if 2drop false exit then
  + 1- dup c@
   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

[edit] Groovy

 // *** print *.txt files in current directory
 new File('.').eachFileMatch(~/.*\.txt/) {
   println it
 }

 // *** print *.txt files in /foo/bar
 new File('/foo/bar').eachFileMatch(~/.*\.txt/) {
   println it
 }

[edit] Haskell

Works with: GHCi version 6.6

In this example, the pattern is a POSIX extended regular expression.

import System.Directory
import Text.Regex

walk :: FilePath -> String -> IO ()
walk dir pattern = do
    filenames <- getDirectoryContents dir
    putStr $ unlines $ filter ((/= Nothing).(matchRegex $ mkRegex pattern)) filenames

main = walk "." ".\\.hs$"

[edit] IDL

 f = file_search('*.txt', count=cc)
 if cc gt 0 then print,f

(IDL is an array language - very few things are ever done in 'loops'.)

[edit] MAXScript

getFiles "C:\\*.txt"

[edit] OCaml

#load "str.cma"
let contents = Array.to_list (Sys.readdir ".") in
let select pat str = Str.string_match (Str.regexp pat) str 0 in
List.filter (select ".*\\.jpg") contents

[edit] Perl

opendir my $dh, 'the_directory';
print map {"$_\n"} grep /foo/, readdir $dh;
closedir $dh;

[edit] PHP

Works with: PHP version 5.2.0

$pattern = 'php';
$dh = opendir('c:/foo/bar'); // Or '/home/foo/bar' for Linux
while (false !== ($file = readdir($dh)))
{
    if ($file != '.' and $file != '..')
    {
        if (preg_match("/$pattern/", $file))
        {
            echo "$file matches $pattern\n";
        }
    }
}

Works with: PHP version 4 >= 4.3.0 or 5

foreach (glob('/home/foo/bar/*.php') as $file){
    echo "$file\n";
}

[edit] Pop11

Built-in procedure sys_file_match searches directories (or directory trees) using shell-like patterns:

lvars repp, fil;
;;; create path repeater
sys_file_match('*.p', '', false, 0) -> repp;
;;; iterate over files
while (repp() ->> fil) /= termin do
     ;;; print the file
     printf(fil, '%s\n');
endwhile;

[edit] Python

The glob library included with Python lists files matching shell-like patterns:

 
 import glob
 for filename in glob.glob('*'):
     print filename
 

[edit] Raven

'dir://.' open each as item
    item m/\.txt$/ if "%(item)s\n" print

[edit] Ruby

# Files under this directory:
Dir.glob('*') { |file| puts file }

# Files under path '/foo/bar':
Dir.glob( File.join('/foo/bar', '*') ) { |file| puts file }

# As a method
def file_match(pattern=/\.txt/, path='.')
  Dir[File.join(path,'*')].each do |file|
    puts file if file =~ pattern
  end
end

[edit] Tcl

 foreach var [glob *.txt] { puts $var }

[edit] Toka

As with the C example, this uses a a POSIX extended regular expression as the pattern. The dir.listByPattern function used here was introduced in library revision 1.3.

 needs shell
 " ."  " .\\.txt$" dir.listByPattern

[edit] Visual Basic .NET

Works with: Visual Basic .NET version 9.0+

 'Using the OS pattern matching
 For Each file In IO.Directory.GetFiles("\temp", "*.txt")
   Console.WriteLine(file)
 Next

 'Using VB's pattern matching and LINQ
 For Each file In (From name In IO.Directory.GetFiles("\temp") Where name Like "*.txt")
   Console.WriteLine(file)
 Next

 'Using VB's pattern matching and dot-notation
 For Each file In IO.Directory.GetFiles("\temp").Where(Function(f) f Like "*.txt")
   Console.WriteLine(file)
 Next

[edit] UnixPipes

ls can take a file globbing pattern too. here using grep for regexp.

ls | grep '\.c$'