GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
 |
errno(3) |
 |
errno − number of last error
#include <errno.h>
extern int errno;
The integer errno is set by system calls (and some library functions) to indicate what went wrong. Its value is significant only when the call returned an error (usually −1), and a library function that does succeed is allowed to change errno.
Sometimes, when −1 is also a legal return value one has to zero errno before the call in order to detect possible errors.
errno is defined by the ISO C standard to be a modifiable lvalue of type int, and must not be explicitly declared; errno may be a macro. errno is thread-local; setting it in one thread does not affect its value in any other thread.
Valid error numbers are all non-zero; errno is never set to zero by any library function. All the error names specified by POSIX.1 must have distinct values.
POSIX.1 (2001 edition) lists the following symbolic error names. Of these, EDOM and ERANGE are in the ISO C standard. ISO C Amendment 1 defines the additional error number EILSEQ for coding errors in multibyte or wide characters.
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E2BIG |
Arg list too long |
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EACCES |
Permission denied |
EADDRINUSE
Address in use
EADDRNOTAVAIL
Address not available
EAFNOSUPPORT
Address family not supported
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EAGAIN |
Resource temporarily unavailable |
EALREADY
Connection already in progress
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EBADF |
Bad file descriptor |
EBADMSG
Bad message
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EBUSY |
Resource busy |
ECANCELED
Operation canceled
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ECHILD |
No child processes |
ECONNABORTED
Connection aborted
ECONNREFUSED
Connection refused
ECONNRESET
Connection reset
EDEADLK
Resource deadlock avoided
EDESTADDRREQ
Destination address required
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EDOM |
Domain error |
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EDQUOT |
Reserved |
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EEXIST |
File exists |
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EFAULT |
Bad address |
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EFBIG |
File too large |
EHOSTUNREACH
Host is unreachable
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EIDRM |
Identifier removed |
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EILSEQ |
Illegal byte sequence |
EINPROGRESS
Operation in progress
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EINTR |
Interrupted function call |
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EINVAL |
Invalid argument |
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EIO |
Input/output error |
EISCONN
Socket is connected
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EISDIR |
Is a directory |
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ELOOP |
Too many levels of symbolic links |
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EMFILE |
Too many open files |
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EMLINK |
Too many links |
EMSGSIZE
Inappropriate message buffer length
EMULTIHOP
Reserved
ENAMETOOLONG
Filename too long
ENETDOWN
Network is down
ENETRESET
Connection aborted by network
ENETUNREACH
Network unreachable
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ENFILE |
Too many open files in system |
ENOBUFS
No buffer space available
ENODATA
No message is available on the STREAM head read queue
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ENODEV |
No such device |
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ENOENT |
No such file or directory |
ENOEXEC
Exec format error
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ENOLCK |
No locks available |
ENOLINK
Reserved
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ENOMEM |
Not enough space |
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ENOMSG |
No message of the desired type |
ENOPROTOOPT
Protocol not available
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ENOSPC |
No space left on device |
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ENOSR |
No STREAM resources |
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ENOSTR |
Not a STREAM |
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ENOSYS |
Function not implemented |
ENOTCONN
The socket is not connected
ENOTDIR
Not a directory
ENOTEMPTY
Directory not empty
ENOTSOCK
Not a socket
ENOTSUP
Not supported
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ENOTTY |
Inappropriate I/O control operation |
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ENXIO |
No such device or address |
EOPNOTSUPP
Operation not supported on socket
EOVERFLOW
Value too large to be stored in data type
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EPERM |
Operation not permitted |
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EPIPE |
Broken pipe |
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EPROTO |
Protocol error |
EPROTONOSUPPORT
Protocol not supported
EPROTOTYPE
Protocol wrong type for socket
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ERANGE |
Result too large |
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EROFS |
Read-only file system |
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ESPIPE |
Invalid seek |
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ESRCH |
No such process |
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ESTALE |
Reserved |
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ETIME |
STREAM ioctl() timeout |
ETIMEDOUT
Operation timed out
ETXTBSY
Test file busy
EWOULDBLOCK
Operation would block (may be same value as EAGAIN)
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EXDEV |
Improper link |
A common mistake is to do
if (somecall()
== -1) {
printf("somecall() failed\n");
if (errno == ...) { ... }
}
where errno no longer needs to have the value it had upon return from somecall(). If the value of errno should be preserved across a library call, it must be saved:
if (somecall()
== -1) {
int errsv = errno;
printf("somecall() failed\n");
if (errsv == ...) { ... }
}
perror(3), strerror(3)
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errno(3) | |