Cygwin, Git Bash, and MSYS2 have a readymade utility called cygpath.exe
just for doing that.
Output type options: -d, --dos print DOS (short) form of NAMEs (C:\PROGRA~1\) -m, --mixed like --windows, but with regular slashes (C:/WINNT) -M, --mode report on mode of file (binmode or textmode) -u, --unix (default) print Unix form of NAMEs (/cygdrive/c/winnt) -w, --windows print Windows form of NAMEs (C:\WINNT) -t, --type TYPE print TYPE form: 'dos', 'mixed', 'unix', or 'windows'