Error Codes In Linux
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In C programming language, there is no direct support for error handling. You have to detect the failure and handle the error. In C programming language, return values represents success or failure. Inside a C program, when a
Linux Exit Codes
function fails, you should handle the errors accordingly, or at least record the errors in linux error numbers a log file. When you are running some program on Linux environment, you might notice that it gives some error number. For example,
Linux Error Codes List
"Error no is : 17", which doesn't really say much. You really need to know what error number 17 means. This article shows all available error numbers along with it descriptions. This article might be a handy reference linux kernel error codes for you, when you encounter an error number and you would like to know what it means. In C programming language, there is an external variable called "errno". From this errno variable you can use some error handling functions to find out the error description and handle it appropriately. You have to include errno.h header file to use external variable errno. perror function prints error description in standard error. The strerror function returns a string describing the unix error codes error code passed in the argument errnum. The following C code snippet tries to open a file through open system call. There are two flags in the open call. O_CREAT flag is to create a file, if the file does not exist. O_EXCL flag is used with O_CREAT, if the file is already exist open call will fail with the proper error number. $ cat fileopen.c #include
DESCRIPTION top The
Linux Errno
the event of an error to indicate what went wrong. Its value is significant linux error codes 127 only when the return value of the call indicated an error (i.e., -1 from most system calls; -1 or NULL from
Linux System Error Codes
most library functions); a function that succeeds is allowed to change errno. Valid error numbers are all nonzero; errno is never set to zero by any system call or library function. For some system calls http://www.thegeekstuff.com/2010/10/linux-error-codes and library functions (e.g., getpriority(2)), -1 is a valid return on success. In such cases, a successful return can be distinguished from an error return by setting errno to zero before the call, and then, if the call returns a status that indicates that an error may have occurred, checking to see if errno has a nonzero value. errno is defined by the ISO C standard to be a modifiable lvalue http://man7.org/linux/man-pages/man3/errno.3.html 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. All the error names specified by POSIX.1 must have distinct values, with the exception of EAGAIN and EWOULDBLOCK, which may be the same. Below is a list of the symbolic error names that are defined on Linux. Some of these are marked POSIX.1, indicating that the name is defined by POSIX.1-2001, or C99, indicating that the name is defined by C99. E2BIG Argument list too long (POSIX.1) EACCES Permission denied (POSIX.1) EADDRINUSE Address already in use (POSIX.1) EADDRNOTAVAIL Address not available (POSIX.1) EAFNOSUPPORT Address family not supported (POSIX.1) EAGAIN Resource temporarily unavailable (may be the same value as EWOULDBLOCK) (POSIX.1) EALREADY Connection already in progress (POSIX.1) EBADE Invalid exchange EBADF Bad file descriptor (POSIX.1) EBADFD File descriptor in bad state EBADMSG Bad message (POSIX.1) EBADR Invalid request descriptor EBADRQC Invalid request code EBADSLT Invalid slot EBUSY Device or resource busy (POSIX.1) ECANCELED Operation canceled (POSIX.1) ECHILD No child processes (POSIX.1) ECHRNG Channel number out of range ECOMM Communication error on send ECONNABORTED Connection aborted (POSIX.1) ECONNREFUSED Connection refused (POSIX.1) ECONNRESET Connection reset (POSIX.1) EDEADLK Resource deadlock avoided (PO
codes can’t occur on GNU systems, but they can occur using the GNU C Library on other systems. Macro: int EPERM Operation not permitted; only the owner of the file (or other resource) or processes with special http://www.gnu.org/s/libc/manual/html_node/Error-Codes.html privileges can perform the operation. Macro: int ENOENT No such file or directory. This is a “file doesn’t exist” error for ordinary files that are referenced in contexts where they are expected to already exist. Macro: int ESRCH No process matches the specified process ID. Macro: int EINTR Interrupted function call; an asynchronous signal occurred and prevented completion of the call. When this happens, you should try the call again. You can choose to error codes have functions resume after a signal that is handled, rather than failing with EINTR; see Interrupted Primitives. Macro: int EIO Input/output error; usually used for physical read or write errors. Macro: int ENXIO No such device or address. The system tried to use the device represented by a file you specified, and it couldn’t find the device. This can mean that the device file was installed incorrectly, or that the physical device is missing linux error codes or not correctly attached to the computer. Macro: int E2BIG Argument list too long; used when the arguments passed to a new program being executed with one of the exec functions (see Executing a File) occupy too much memory space. This condition never arises on GNU/Hurd systems. Macro: int ENOEXEC Invalid executable file format. This condition is detected by the exec functions; see Executing a File. Macro: int EBADF Bad file descriptor; for example, I/O on a descriptor that has been closed or reading from a descriptor open only for writing (or vice versa). Macro: int ECHILD There are no child processes. This error happens on operations that are supposed to manipulate child processes, when there aren’t any processes to manipulate. Macro: int EDEADLK Deadlock avoided; allocating a system resource would have resulted in a deadlock situation. The system does not guarantee that it will notice all such situations. This error means you got lucky and the system noticed; it might just hang. See File Locks, for an example. Macro: int ENOMEM No memory available. The system cannot allocate more virtual memory because its capacity is full. Macro: int EACCES Permission denied; the file permissions do not allow the attempted operation. Macro: int EFAULT Bad address; an invalid pointer was detected. On GNU/Hurd systems, this error never happens; you ge