Tutorial :Regarding error numbers in Linux


Is there any link or material where I can learn more about the different error numbers in Linux ??

At present in man errno I get a single line for each error number but I would like to know the conditions or chances for which particular error occurs (A more detailed description in short words)

For e.g.

EADDRNOTAVAIL 99 /* Cannot assign requested address */  

Above error occurs when a socket tried to bind to ip-address which is not present locally in the machine .. Similarly for all other errors is there any wiki or material for detailed information ??


Well, since errors generally occur while doing something, your best bet is to look up the man page for "something".

For example, if you get back an errno of 34 from your fscanf() call, you would first do:

grep 34 $(find /usr/include -name '*errno*h')  

to figure out what the error was:

/usr/include/bits/errno.h:#define ERANGE 34 /* Math result not representable. */  /usr/include/asm-generic/errno-base.h:#define ERANGE 34 /* Math result not ... */  

Then, looking at the man page for fscanf(), you see:

ERANGE - The result of an integer conversion would exceed the size           that can be stored in the corresponding integer type.  

and you would (hopefully) be able to figure it out from there.

If you want a list of the errors and (brief) description, modify the grep above as follows:

grep define $(find /usr/include -name '*errno*h') | less  

and browse the output.

And, if you still don't know about the error and what caused it (the descriptions are a little terse, I'll agree), I would just bung it (e.g., EADDRNOTAVAIL) into that little dialog box in the top right corner of your browser1 and you'll get back something like this (or many other wonderful pages):

Cannot assign requested address
You are attempting to bind(2) to a local address that isn't local. For example if the IP addresses of a machine are and and you're trying to bind to, you are going to get this error. Check to make sure the address you are trying to bind to exists on the machine you are trying to bind it from.
This error can also come up if you're doing a "pre-bound connect", where you're first binding to a local port, then doing an outbound connect with a socket. If the local port is already connected to the given remote IP and port (i.e., there's already an identical socketpair), you'll receive this error (value = 99 on Linux).
4 pages link to EADDRNOTAVAIL:
     - bind(2)
     - connect(2)
     - setsockopt(2)
     - packet(7)

Go ahead, try it with other error values as well, it's not too bad.

1 You are using Firefox, right? :-)


Error codes are fairly generic, and are meaningful only within the context of a particular function. So there isn't much advantage in learning all the error codes, as they may mean subtly different things for different functions and have to be handled differently anyway.

"ERRORS" section in the function's man page will tell you what codes are possible for its return values or errno and why they occur.


If it's GLIBC, try using %m in a printf() statement:

#include <errno.h>  ...  int fh = fopen(...);  if (0 > fh) printf("Couldn't open the file: %d, %m\n", errno);  

Very useful.


Its API specfic. I have not heard about a generic error list. However :

Many functions provide an error number in errno, which has type int  and is defined in <errno.h>.  

So you can have a look at the header file errno.h. Similarly Glib has different codes for error reporting.

EDIT: Well if you already know the error code then you can always google to get more information on that error, if you find man page unsatisfactory.


As other posters have suggested, the best source for decoding what errors really mean in context is the appropriate man page. For networking protocols, the appropriate man page may be something other than the system call; for IP sockets, try ip(7), which gives a tiny bit more information:

   EADDRNOTAVAIL            A nonexistent interface was requested or  the  requested  source            address was not local.  

More error codes are described in tcp(7) and udp(7).


this program can also do the trick..

#include<stdio.h>  #include<string.h>    int main()  {          int i= 0 ;            for ( i = 0 ; i<=132; i++ )          {                  printf("no %d == %s \n", i , strerror(i));          }  }  
no 0 == Success  no 1 == Operation not permitted  no 2 == No such file or directory  no 3 == No such process  no 4 == Interrupted system call  no 5 == Input/output error  no 6 == No such device or address  no 7 == Argument list too long  no 8 == Exec format error  no 9 == Bad file descriptor  no 10 == No child processes  no 11 == Resource temporarily unavailable  no 12 == Cannot allocate memory  no 13 == Permission denied  no 14 == Bad address  no 15 == Block device required  no 16 == Device or resource busy  no 17 == File exists  no 18 == Invalid cross-device link  no 19 == No such device  no 20 == Not a directory  no 21 == Is a directory  no 22 == Invalid argument  no 23 == Too many open files in system  no 24 == Too many open files  no 25 == Inappropriate ioctl for device  no 26 == Text file busy  no 27 == File too large  no 28 == No space left on device  no 29 == Illegal seek  no 30 == Read-only file system  no 31 == Too many links  no 32 == Broken pipe  no 33 == Numerical argument out of domain  no 34 == Numerical result out of range  no 35 == Resource deadlock avoided  no 36 == File name too long  no 37 == No locks available  no 38 == Function not implemented  no 39 == Directory not empty  no 40 == Too many levels of symbolic links  no 41 == Unknown error 41  no 42 == No message of desired type  no 43 == Identifier removed  no 44 == Channel number out of range  no 45 == Level 2 not synchronized  no 46 == Level 3 halted  no 47 == Level 3 reset  no 48 == Link number out of range  no 49 == Protocol driver not attached  no 50 == No CSI structure available  no 51 == Level 2 halted  no 52 == Invalid exchange  no 53 == Invalid request descriptor  no 54 == Exchange full  no 55 == No anode  no 56 == Invalid request code  no 57 == Invalid slot  no 58 == Unknown error 58  no 59 == Bad font file format  no 60 == Device not a stream  no 61 == No data available  no 62 == Timer expired  no 63 == Out of streams resources  no 64 == Machine is not on the network  no 65 == Package not installed  no 66 == Object is remote  no 67 == Link has been severed  no 68 == Advertise error  no 69 == Srmount error  no 70 == Communication error on send  no 71 == Protocol error  no 72 == Multihop attempted  no 73 == RFS specific error  no 74 == Bad message  no 75 == Value too large for defined data type  no 76 == Name not unique on network  no 77 == File descriptor in bad state  no 78 == Remote address changed  no 79 == Can not access a needed shared library  no 80 == Accessing a corrupted shared library  no 81 == .lib section in a.out corrupted  no 82 == Attempting to link in too many shared libraries  no 83 == Cannot exec a shared library directly  no 84 == Invalid or incomplete multibyte or wide character  no 85 == Interrupted system call should be restarted  no 86 == Streams pipe error  no 87 == Too many users  no 88 == Socket operation on non-socket  no 89 == Destination address required  no 90 == Message too long  no 91 == Protocol wrong type for socket  no 92 == Protocol not available  no 93 == Protocol not supported  no 94 == Socket type not supported  no 95 == Operation not supported  no 96 == Protocol family not supported  no 97 == Address family not supported by protocol  no 98 == Address already in use  no 99 == Cannot assign requested address  no 100 == Network is down  no 101 == Network is unreachable  no 102 == Network dropped connection on reset  no 103 == Software caused connection abort  no 104 == Connection reset by peer  no 105 == No buffer space available  no 106 == Transport endpoint is already connected  no 107 == Transport endpoint is not connected  no 108 == Cannot send after transport endpoint shutdown  no 109 == Too many references: cannot splice  no 110 == Connection timed out  no 111 == Connection refused  no 112 == Host is down  no 113 == No route to host  no 114 == Operation already in progress  no 115 == Operation now in progress  no 116 == Stale NFS file handle  no 117 == Structure needs cleaning  no 118 == Not a XENIX named type file  no 119 == No XENIX semaphores available  no 120 == Is a named type file  no 121 == Remote I/O error  no 122 == Disk quota exceeded  no 123 == No medium found  no 124 == Wrong medium type  no 125 == Operation canceled  no 126 == Required key not available  no 127 == Key has expired  no 128 == Key has been revoked  no 129 == Key was rejected by service  no 130 == Owner died  no 131 == State not recoverable  no 132 == Unknown error 132  

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