Walk a directory/Recursively

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: Please be careful when running any code examples found here.

E

def walkTree(directory, pattern) {
  for name => file in directory {
    if (name =~ rx`.*$pattern.*`) {
      println(file.getPath())
    }
    if (file.isDirectory()) {
      walkTree(file, pattern)
    }
  }
}

Example:

? walkTree(<file:/usr/share/man>, "rmdir")
/usr/share/man/man1/rmdir.1
/usr/share/man/man2/rmdir.2

Forth

Interpreter: gforth 0.6.2

Todo: track the full path and print it on matching files.

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

Groovy

Print all text files in the current directory tree

new File('.').eachFileRecurse {
  if (it.name =~ /.*\.txt/) println it;
}

IDL

 result = file_search( directory, '*.txt', count=cc )

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"

Java

Compiler: javac, JDK 1.4 and up

Done using no pattern. But with end string comparison which gave better results.

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 descent into the directory tree and find all the file 
     * 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());
                    }
                }
            }
        }
    }
}

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"

Perl

Interpreter: Perl 5.x

use File::Find qw(find);
my $dir     = '.';
my $pattern = 'foo';
find sub {print $File::Find::name if /$pattern/}, $dir;

Pop11

Builtin procedure sys_file_match searches directories or directory trees using shell-like patterns (three dots indicate search for subdirectory tree).

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;

Python

Interpreter: Python 2.5

 import fnmatch
 import os
 
 rootPath = '/'
 pattern = '*.mp3' # Can include any UNIX shell-style wildcards

 for root, dirs, files in os.walk(rootPath):
     for filename in files:
         if fnmatch.fnmatch(filename, pattern):
             print os.path.join(root, filename)

This uses the os.walk() "generator" which is considered easier and more "Pythonic" than the use of the "visitor"-based os.path.walk() in the previous example.

Interpreter: Python older then 2.2

A more strictly comparable port of this 2.5 code to earlier versions of Python would be:

from fnmatch import fnmatch
import os, os.path
def print_fnmatches(pattern, dir, files):
    for filename in files:
        if fnmatch(name, pattern):
            print os.path.join(dir, filename)
os.path.walk('/', print_fnmatches, '*.mp3')

Interpreter: Python 2.5

Libraries: Path *(Note: This uses a non-standard replacement to the os.path module)

 from path import path
 
 rootPath = '/'
 pattern = '*.mp3'
 
 d = path(rootPath)
 for f in d.walkfiles(pattern):
   print f

Ruby

Pattern matching using regular expressions

 #define a recursive function that will traverse the directory tree
 def printAndDescend(pattern)
   #we keep track of the directories, to be used in the second, recursive part of this function
   directories=[]
   Dir['*'].sort.each do |name|
     if File.file?(name) and name[pattern]
       puts(File.expand_path(name))
     elsif File.directory?(name)
       directories << name
     end
   end
   directories.each do |name|
     #don't descend into . or .. on linux
     Dir.chdir(name){printAndDescend(pattern)} if !Dir.pwd[File.expand_path(name)]
   end
 end
 #print all ruby files
 printAndDescend(/.+\.rb$/)

Or use the Find core Module

 require 'find'
 
 def find_and_print(path, pattern)
   Find.find(path) do |entry|
     if File.file?(entry) and entry[pattern]
       puts entry
     end
   end
 end
 
 # print all the ruby files
 find_and_print(".", /.+\.rb$/)

Or, to find and print all files under '/foo/bar' the easy way:

 Dir.glob( File.join('/foo/bar', '**', '*') ) { |file| puts file }

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

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.single(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)
}

Class RichFile gets a java.io.File in constructor. Its two methods returns Iterables on items of type File. children allow iterations on the direct children (empty if file is not a directory). andTree contains file and all files below, as a concatenation (++) of a a sequence which contains only file (Seq.single) and actual descendants. 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 object RichFile is to publish 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 :

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)
}

Tcl

Interpreter: Tcl 8.4

proc walkin { fromDir } {
    foreach fname [glob -nocomplain -directory $fromDir *] {
        if { [file isdirectory $fname] } {
            walkin $fname
        } else {
            if { [string match *.mp3 $fname] } {
                puts [file normalize $fname]
            }
        }
    }
}
# replace directory with something appropriate
walkin /home/user