What are all the ways to traverse directory trees? - language-agnostic

Question

How do you traverse a directory tree in your favorite language?
What do you need to know to traverse a directory tree in different operating systems? On different filesystems?
What's your favorite library/module for aiding in traversing a directory tree?

Answer 1

In Python:
If you're looking for a quick, clean, and portable solution try:
import os
base_dir = '.'
def foo(arg, curr_dir, files):
print curr_dir
print files
os.path.walk(base_dir, foo, None)
Note that you can modify foo to do something else instead of just printing the names. Furthermore, if you're interested in migrating to Python 3.0, you will have to use os.walk() instead.

Answer 2

In Java:
Recursion is useful here. Following is a Java code snippet that's been all over the Internet for ages. Not sure who deserves the credit for it.
// Process all files and directories under dir
public static void visitAllDirsAndFiles(File dir) {
process(dir); //do something useful with the file or dir
if (dir.isDirectory()) {
String[] children = dir.list();
for (int i=0; i<children.length; i++) {
visitAllDirsAndFiles(new File(dir, children[i]));
}
}
}

Answer 3

bash:
#!/bin/bash
function walk_tree {
echo "Directory: $1"
local directory="$1"
local i
for i in "$directory"/*;
do
echo "File: $i"
if [ "$i" = . -o "$i" = .. ]; then
continue
elif [ -d "$i" ]; then # Process directory and / or walk-down into directory
# add command here to process all files in directory (i.e. ls -l "$i/"*)
walk_tree "$i" # DO NOT COMMENT OUT THIS LINE!!
else
continue # replace continue to process individual file (i.e. echo "$i")
fi
done
}
walk_tree $HOME
(adapted from http://ubuntuforums.org/showthread.php?t=886272 Comment #4)

Answer 4

In C#:
Stack<DirectoryInfo> dirs = new Stack<DirectoryInfo>();
dirs.Push(new DirectoryInfo("C:\\"));
while (dirs.Count > 0) {
DirectoryInfo current = dirs.Pop();
// Do something with 'current' (if you want)
Array.ForEach(current.GetFiles(), delegate(FileInfo f)
{
// Do something with 'f'
});
Array.ForEach(current.GetDirectories(), delegate(DirectoryInfo d)
{
dirs.Push(d);
});
}

Answer 5

C++
#include <utility>
#include <boost/filesystem.hpp>
#include <boost/foreach.hpp>
#define foreach BOOST_FOREACH
namespace fs = boost::filesystem;
fs::recursive_directory_iterator it(top), eod;
foreach (fs::path const & p, std::make_pair(it, eod)) {
if (is_directory(p)) {
...
} else if (is_regular_file(p)) {
...
} else if (is_symlink(p)) {
...
}
}

Answer 6

On Linux with GNU tools
find -print0 | xargs -0 md5sum
or
find -print0 | xargs -0 -iASD echo 'this file "ASD" should be dealt with lile this (ASD)'

Answer 7

mmmm, C# with a dose of recursion.....
public static List<string> CrawlPath(string path, bool IncludeSubFolders)
{
List<string> fileList = new List<string>();
try
{
Stack<string> filez = new Stack<string>(Directory.GetFiles(path));
while (filez.Count > 0)
{
fileList.Add(filez.Pop());
}
if (IncludeSubFolders)
{
filez = new Stack<string>(Directory.GetDirectories(path));
while (filez.Count > 0)
{
string curDir = filez.Pop();
fileList.AddRange(CrawlPath(curDir, IncludeSubFolders));
}
}
}
catch (System.Exception err)
{
Console.WriteLine("Error: " + err.Message);
}
return fileList;
}