Appendix B. UNIX Error Messages

Errors generated by the failure of a system call or library function, can be displayed using the perror or strerror library function calls (see "Managing Failures" Section 1.5, "Managing System Call Failures"). For example, the error messages returned by strerror on a Linux system can be displayed in their entirety using Program B.1.

Program B.1 Displaying strerror messages.

File : errors.cxx
 #include 
 #include 
 #include 
 extern int sys_nerr;
 + using namespace std;
 int
 main( ){
 for (int err=0; err < sys_nerr; ++err )
 cout << err << '	' << strerror(err) << endl;
 10 return 0;
 }

As the output of the program will fill more than one screen, it may be helpful to redirect the output to either a file, for future reference, or to the more command to permit viewing of the output at a controlled pace. To compile the source file and capture the output of the program in a file called emessages , the command sequence is

linux$ g++ errors.cxx -o errors
linux$ errors > emessages

If, after compilation, you want the program output to be piped to more , the command sequence is

linux$ errors more

Note that the error message returned by strerror (and perror ) in a C/C++ program is the same message that is returned by the Linux command-line utility called perror . A command-line sequence to determine the error message associated with error number 13 is

linux$ perror 13
Error code 13: Permission denied

A Bourne shell script that uses the command-line perror utility to display all error messages is shown in Program B.2.

Program B.2 Bourne shell script that uses perror to generate error messages.

File : errors_script
 #! /bin/bash
 err=0
 while test $err -lt 125; do
 echo -n "$err "
 + perror -s $err
 err='expr $err + 1'
 done

Table B.1 lists the error number, its symbolic name , and the actual message generated by strerror .

Table B.1. Error messages.

Error #	Symbolic Constant	Message Generated by strerror
		Success
1	EPERM	Operation not permitted
2	ENOENT	No such file or directory
3	ESRCH	No such process
4	EINTR	Interrupted system call
5	EIO	Input/output error
6	ENXIO	No such device or address
7	E2BIG	Argument list too long
8	ENOEXEC	exec format error
9	EBADF	Bad file descriptor
10	ECHILD	No child processes
11	EAGAIN	Resource temporarily unavailable
12	ENOMEM	Cannot allocate memory
13	EACCES	Permission denied
14	EFAULT	Bad address
15	ENOTBLK	Block device required
16	EBUSY	Device or resource busy
17	EEXIST	File exists
18	EXDEV	Invalid cross-device link
19	ENODEV	No such device
20	ENOTDIR	Not a directory
21	EISDIR	Is a directory
22	EINVAL	Invalid argument
23	ENFILE	Too many open files in system
24	EMFILE	Too many open files
25	ENOTTY	Inappropriate ioctl for device
26	ETXTBSY	Text file busy
27	EFBIG	File too large
28	ENOSPC	No space left on device
29	ESPIPE	Illegal seek
30	EROFS	Read-only file system
31	EMLINK	Too many links
32	EPIPE	Broken pipe
33	EDOM	Numerical argument out of domain
34	ERANGE	Numerical result out of range
35	EDEADLK	Resource deadlock avoided
36	ENAMETOOLONG	File name too long
37	ENOLCK	No locks available
38	ENOSYS	Function not implemented
39	ENOTEMPTY	Directory not empty
40	ELOOP	Too many levels of symbolic links
41	EWOULDBLOCK	Unknown error 41
42	ENOMSG	No message of desired type
43	EIDRM	Identifier removed
44	ECHRNG	Channel number out of range
45	EL2NSYNC	Level 2 not synchronized
46	EL3HLT	Level 3 halted
47	EL3RST	Level 3 reset
48	ELNRNG	Link number out of range
49	EUNATCH	Protocol driver not attached
50	ENOCSI	No CSI structure available
51	EL2HLT	Level 2 halted
52	EBADE	Invalid exchange
53	EBADR	Invalid request descriptor
54	EXFULL	Exchange full
55	ENOANO	No anode
56	EBADRQC	Invalid request code
57	EBADSLT	Invalid slot
58	EDEADLOCK	Unknown error 58
59	EBFONT	Bad font file format
60	ENOSTR	Device not a stream
61	ENODATA	No data available
62	ETIME	Timer expired
63	ENOSR	Out of streams resources
64	ENONET	Machine is not on the network
65	ENOPKG	Package not installed
66	EREMOTE	Object is remote
67	ENOLINK	Link has been severed
68	EADV	Advertise error
69	ESRMNT	Srmount error
70	ECOMM	Communication error on send
71	EPROTO	Protocol error
72	EMULTIHOP	Multihop attempted
73	EDOTDOT	RFS-specific error
74	EBADMSG	Bad message
75	EOVERFLOW	Value too large for defined data type
76	ENOTUNIQ	Name not unique on network
77	EBADFD	File descriptor in bad state
78	EREMCHG	Remote address changed
79	ELIBACC	Can not access a needed shared library
80	ELIBBAD	Accessing a corrupted shared library
81	ELIBSCN	.lib section in a.out corrupted
82	ELIBMAX	Attempting to link in too many shared libraries
83	ELIBEXEC	Cannot exec a shared library directly
84	EILSEQ	Invalid or incomplete multibyte or wide character
85	ERESTART	Interrupted system call should be restarted
86	ESTRPIPE	Streams pipe error
87	EUSERS	Too many users
88	ENOTSOCK	Socket operation on nonsocket
89	EDESTADDRREQ	Destination address required
90	EMSGSIZE	Message too long
91	EPROTOTYPE	Protocol wrong type for socket
92	ENOPROTOOPT	Protocol not available
93	EPROTONOSUPPORT	Protocol not supported
94	ESOCKTNOSUPPORT	Socket type not supported
95	EOPNOTSUPP	Operation not supported
96	EPFNOSUPPORT	Protocol family not supported
97	EAFNOSUPPORT	Address family not supported by protocol
98	EADDRINUSE	Address already in use
99	EADDRNOTAVAIL	Cannot assign requested address
100	ENETDOWN	Network is down
101	ENETUNREACH	Network is unreachable
102	ENETRESET	Network dropped connection on reset
103	ECONNABORTED	Software caused connection abort
104	ECONNRESET	Connection reset by peer
105	ENOBUFS	No buffer space available
106	EISCONN	Transport endpoint is already connected
107	ENOTCONN	Transport endpoint is not connected
108	ESHUTDOWN	Cannot send after transport endpoint shutdown
109	ETOOMANYREFS	Too many references: cannot splice
110	ETIMEDOUT	Connection timed out
111	ECONNREFUSED	Connection refused
112	EHOSTDOWN	Host is down
113	EHOSTUNREACH	No route to host
114	EALREADY	Operation already in progress
115	EINPROGRESS	Operation now in progress
116	ESTALE	Stale NFS file handle
117	EUCLEAN	Structure needs cleaning
118	ENOTNAM	Not a XENIX named type file
119	ENAVAIL	No XENIX semaphores available
120	EISNAM	Is a named type file
121	EREMOTEIO	Remote I/O error
122	EDQUOT	Disk quota exceeded
123	ENOMEDIUM	No medium found
124	EMEDIUMTYPE	Wrong medium type

Keep in mind that in C/C++ programs it is always best to reference a specific error by its symbolic constant, as the underlying numeric value for an error can change from one implementation of UNIX to another (and even from one version of the same implementation to the next ). For example, in Solaris 2.8 (EBADRInvalid request descriptor) is associated with error number 51; in Red Hat Linux 7.3 this same error is associated with error number 53. Likewise, EIDRMIdentifier removed, is error number 43 in Red Hat Linux 7.3 but is error number 37 in Solaris 2.8.

In addition to error messages the command-line perror utility returns MyISAM/ISAM [1] table-handler error codes and messages. These codes and their associated messages are shown in Table B.2. Again, as with other error messages, these are mostly system-dependent.

[1] ISAM is short for Indexed Sequential Access Method a technique for storing and retrieving data.

Table B.2. MyISAM/ISAM Error Messages.

Error #	MyISAM/ISAM Message Generated by perror
120	Didn't find key on read or update
121	Duplicate key on write or update
122
123	Someone has changed the row since it was read
124
126	Index file is crashed/wrong file format
127	Record file is crashed
131	Command not supported by database
132	Old database file
133	No record read before update
134	Record was already deleted (or record file crashed)
135	No more room in record file
136	No more room in index file
137	No more records (read after end of file)
138	Unsupported extension used for table
139	Too big row (>= 16 M)
140	Wrong create options
141	Duplicate unique key or constraint on write or update
142	Unknown character set used
143	Conflicting table definition between MERGE and mapped table
144	Table is crashed and last repair failed
145	Table was marked as crashed and should be repaired
146	Lock timed out; retry transaction
147	Lock table is full; restart program with a larger lock table
148	Updates are not allowed under a read-only transaction
149	Lock deadlock; retry transaction