postcat version (return code: 0)
postcat: warning: close version: Is a directory
postcat -HELP (return code: -15)
postcat: invalid option -- '-'
postcat: fatal: usage: postcat [-b (body text)] [-c config_dir] [-d (decimal record type)] [-e (envelope records)] [-h (header text)] [-q (access queue)] [-v] [file(s)...]