Check file read+write permissions

#!/usr/bin/env python
import sys, errno

if __name__ == "__main__":
    try:
        with open(sys.argv[1]) as f:
            s = f.read()
            print('read', len(s), 'bytes.')
    except IOError as x:
        if x.errno == errno.ENOENT:
            print(sys.argv[1], '- does not exist')
        elif x.errno == errno.EACCES:
            print(sys.argv[1], '- cannot be read')
        else:
            print(sys.argv[1], '- some other error')