After being away from the Windows developer world for a few years, I have been pleased to find some of the nice things that Microsoft has given us. Visual Studio has some really nice refactoring capabilities. The Windows 7 user experience rivals OS X. And as an alternative to the venerable
cmd.exe, we now have a much better command-line shell: PowerShell.
What I like most about PowerShell is that it feels more like a UNIX shell. It supports a lot of UNIXy commands (
cat). It lets you use either forward slashes or backslashes in paths This is good for someone like me who can never remember what OS I'm using when I start typing a command.
But of course, Microsoft can't give us something new without throwing in some surprisingly inappropriate behavior.
A couple of days ago, I needed to create a patch for a Subversion repository, and so I typed the typical command to do so (which works fine in UNIX shells and with
svn diff > my_patch.diff
I then looked at my patch to verify that it looked good:
cat my_patch.diff | more
Everything looked fine. However, when I later tried to apply the patch to another Subversion workspace:
patch -p0 -i my_patch.diff
I got errors. I opened up
my_patch.diff in Vim, and realized it was a UTF-16-encoded file.
patch know how to deal with Unicode. How did this happen?
After wasting an hour trying various
svn command-line options and diff utilities, I finally stumbled onto the answer. It turns out that, in PowerShell,
svn diff > my_patch.diff is equivalent to this command:
svn diff | out-file my_patch.diff
and (get this), the
out-file cmdlet encodes its output as UTF-16 by default, regardless of what the input encoding was.
This default behavior makes sense for
out-file, but it is counter-intuitive that the
> redirection operator would take ASCII and convert it to Unicode.
To make PowerShell do the right thing, you have to do this:
svn diff | out-file -encoding ascii my_patch.diff