standard Unix exit codes

UNIX (Symbol) Exit Value EX_OK 0 No errors during session. EX_USAGE 64 Command line usage error. The command was used incorrectly (wrong number of arguments, bad flag, bad syntax in a parameter, or whatever). EX_DATAERR 65 Data format error. The user's input data was incorrect in some way. EX_NOINPUT 66 Cannot open input. User's input file did not exist or was not readable. EX_NOUSER 67 Addressee unknown. User specified does not exist. EX_NOHOST 68 Host name unknown. Host specified does not exist. Used in mail addresses or network requests. EX_UNAVAILABLE 69 Service unavailable. Occurs if a support program or file does not exist. Can be used as a catchall message when not known why something is not working. EX_SOFTWARE 70 Internal software error inconsistency, etc. in HSI code (non-operating system- related errors). EX_OSERR 71 Operating system error, such as cannot fork, cannot create pipe, getuid, returning a non-existent user, etc.. EX_OSFILE 72 Critical OS file missing, cannot be opened, or has some sort of error (syntax error). EX_CANTCREAT 73 Cannot create user output file. EX_IOERR 74 Input/output error, occurred while doing I/O on some file. EX_TEMPFAIL 75 Temporary failure. User is invited to retry. EX_PROTOCOL 76 Remote error in protocol. The remote system returned something that was not possible during a protocol exchange. EX_NOPERM 77 Permission denied. User did not have sufficient permission to perform the operation.