Killing Mind

bash and the other shells make scripting the file system a joy. The speed and simplicity of applying command line tools to groups of files is immensely powerful. It's unfortunate then, that the most straightforward approach to iterating subdirectories and files fails miserably when it comes to filenames with spaces.

#!/bin/bash
 
src="/my/path"
    
for dir in `ls "$src/"`
do
  if [ -d "$src/$dir" ]; then
    #uh oh - $dir will never match paths with spaces
  fi
done

It seems that many people, when faced with this barrier, ultimately turn to (slightly) more complicated solutions like Perl, Python or find. It occurs to me that this is a pity, since this simple addition puts you straight back on the path:

#!/bin/bash
 
src="/my/path"
 
#enable for loops over items with spaces in their name
IFS=$'\n'
 
for dir in `ls "$src/"`
do
  if [ -d "$src/$dir" ]; then
    #yay, we get matches!
  fi
done

That (IFS=$'\n') is all there is to it! Revel in the simplicity and power of the shell once again!

As a matter of illustration, the script I ended up coding looks like this. It resets the last modified dates on a copy of a set of files, which are grouped into subfolders.

#!/bin/bash
 
src='/path/to/original/documents'
dst='/path/to/copy'
 
#enable for loops over items with spaces in their name
IFS=$'\n'
 
for dir in `ls "$src/"`
do
  if [ -d "$dst/$dir" ]; then
    for f in `ls "$src/$dir"`
    do
      if [ -f "$dst/$dir/$f" ]; then
        touch -m -r "$src/$dir/$f" "$dst/$dir/$f"
      fi
    done
  fi
done
 
echo
echo "Done."
echo

Now take a look what I came up with using Windows. The available scripting environment (JScript? VBScript? WHS?) available in Windows XP is just appalling.

After several frustrating hours wading through the philosophical but vacuous documentation on Microsoft's site I finally came up with this.

option explicit
 
if WScript.Arguments.Count <> 2 then
  WScript.echo "Supply two arguments, the source folder then the destination folder"
  WScript.Quit
end if
 
'folders
dim fsSrc, fsDst, rootSrc, rootDst, dirsSrc, dirsDst, dirSrc, dirDst
'files
dim filesSrc, filesDst, fileSrc, fileDst
 
'create file system objects
set fsSrc = CreateObject("Scripting.FileSystemObject")
set fsDst = CreateObject("Scripting.FileSystemObject")
 
set rootSrc = fsSrc.GetFolder(WScript.Arguments(0))
set rootDst = fsDst.GetFolder(WScript.Arguments(1))
 
set dirsSrc = rootSrc.SubFolders
set dirsDst = rootDst.SubFolders
 
for each dirSrc in dirsSrc
  set dirDst = dirsDst.Item(dirSrc.name)
 	
  set filesSrc = dirSrc.Files
  set filesDst = dirDst.Files
  for each fileSrc in filesSrc
    set fileDst = filesDst.Item(fileSrc.name)
 		
    fileDst.DateLastModified = fileSrc.DateLastModified
  next
 	
next
 
WScript.echo
WScript.echo "Done."
WScript.echo

And guess what! It still doesn't work! Turns out DateLastModified is a read-only property. It seems the only way forward is to wrap a port of the Unix touch program in a VBScript and attempt to call that. Who knows what dramas that will cause with date formats and whatnot.

Sigh.