archive_command = 'test ! -f /path/to/archive/%f && cp %p /path/to/archive/%f'

test ! -f /path/to/archive/00000001000000A900000065 && cp pg_xlog/00000001000000A900000065 /path/to/archive/00000001000000A900000065

restore_command = 'cp /path/to/archive/%f %p'

scp /master/path/to/archive/* /slave/path/to/archive/