msys path conversion (or cygpath for msys?)

Update (Aug-2016):

This question is no longer relevant, as msys2 now comes with cygpath in its installation.

I’ll summarize my research here.

The cygpath equivalent in MSYS is to use this command:

{ cd /c/some/path && pwd -W; } | sed 's""\\|g'

The problem with this approach is that it requires existing path, e.g. the c:\some\path has to be an existing directory; however, real cygpath supports paths that do not exist.

So, if you need to get path to a directory that doesn’t exist, then you can fallback to sed conversion of the path:

{ cd 2>/dev/null /c/some/path && pwd -W ||
  echo /c/some/path | sed 's|^/\([a-z,A-Z]\)/|\1:/|'; } | sed 's""\\|g'

The mouthful of slashes is there to satisfy quoting rules of sed. So, if c:\some\path doesn’t exist on your PC, it will try to convert forward to back slashes and replace /c/ with c:\ (or any other drive letter). The only drawback for this is that it won’t work correctly non-existing paths that contain a mounted component, such as /bin/does-not-exist or /usr/bin/does-not-exist.

One more approach is to use cygpath from cygwin in MSYS. It seems that cygwin sets global environment variable CYGPATH, that is, you can use it from regular cmd.exe:

%CYGPATH% -w /c/some/path

or from MSYS:

$CYGPATH -w /c/some/path

as long as you set to point /c to /cygdrive/c in cygwin.
But this approach will print you /usr located in cygwin installation, not in MSYS.

In short, I think msys should really include real cygpath in the default set of tools just for some cases that aren’t handled automatically by msys command line argument conversion logic

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