(path)
return res
Expand shell variables of the forms $var, ${var} and %var%.

    Unknown variables are left unchanged.
Expand shell variables of the forms $var, ${var} and %var%.
Expand shell variables of the forms $var $ { var } and %var% .
def expandvars(path):
    """Expand shell variables of the forms $var, ${var} and %var%.

    Unknown variables are left unchanged."""
    if '$' not in path and '%' not in path:
        return path
    import string
    varchars = string.ascii_letters + string.digits + '_-'
    res = ''
    index = 0
    pathlen = len(path)
    while index < pathlen:
        c = path[index]
        if c == '\'':   # no expansion within single quotes
            path = path[index + 1:]
            pathlen = len(path)
            try:
                index = path.index('\'')
                res = res + '\'' + path[:index + 1]
            except ValueError:
                res = res + path
                index = pathlen - 1
        elif c == '%':  # variable or '%'
            if path[index + 1:index + 2] == '%':
                res = res + c
                index = index + 1
            else:
                path = path[index+1:]
                pathlen = len(path)
                try:
                    index = path.index('%')
                except ValueError:
                    res = res + '%' + path
                    index = pathlen - 1
                else:
                    var = path[:index]
                    if var in os.environ:
                        res = res + os.environ[var]
                    else:
                        res = res + '%' + var + '%'
        elif c == '$':  # variable or '$$'
            if path[index + 1:index + 2] == '$':
                res = res + c
                index = index + 1
            elif path[index + 1:index + 2] == '{':
                path = path[index+2:]
                pathlen = len(path)
                try:
                    index = path.index('}')
                    var = path[:index]
                    if var in os.environ:
                        res = res + os.environ[var]
                    else:
                        res = res + '${' + var + '}'
                except ValueError:
                    res = res + '${' + path
                    index = pathlen - 1
            else:
                var = ''
                index = index + 1
                c = path[index:index + 1]
                while c != '' and c in varchars:
                    var = var + c
                    index = index + 1
                    c = path[index:index + 1]
                if var in os.environ:
                    res = res + os.environ[var]
                else:
                    res = res + '$' + var
                if c != '':
                    index = index - 1
        else:
            res = res + c
        index = index + 1
    return res
def expandvars ( path ) : if '$' not in path and '%' not in path : return path import string varchars = string . ascii_letters + string . digits + '_-' res = '' index = 0 pathlen = len ( path ) while index < pathlen : c = path [ index ] if c == '\'' : # no expansion within single quotes path = path [ index + 1 : ] pathlen = len ( path ) try : index = path . index ( '\'' ) res = res + '\'' + path [ : index + 1 ] except ValueError : res = res + path index = pathlen - 1 elif c == '%' : # variable or '%' if path [ index + 1 : index + 2 ] == '%' : res = res + c index = index + 1 else : path = path [ index + 1 : ] pathlen = len ( path ) try : index = path . index ( '%' ) except ValueError : res = res + '%' + path index = pathlen - 1 else : var = path [ : index ] if var in os . environ : res = res + os . environ [ var ] else : res = res + '%' + var + '%' elif c == '$' : # variable or '$$' if path [ index + 1 : index + 2 ] == '$' : res = res + c index = index + 1 elif path [ index + 1 : index + 2 ] == '{' : path = path [ index + 2 : ] pathlen = len ( path ) try : index = path . index ( '}' ) var = path [ : index ] if var in os . environ : res = res + os . environ [ var ] else : res = res + '${' + var + '}' except ValueError : res = res + '${' + path index = pathlen - 1 else : var = '' index = index + 1 c = path [ index : index + 1 ] while c != '' and c in varchars : var = var + c index = index + 1 c = path [ index : index + 1 ] if var in os . environ : res = res + os . environ [ var ] else : res = res + '$' + var if c != '' : index = index - 1 else : res = res + c index = index + 1 return res