The errno values, in various formats you may encounter. The standard errno is a positive number, linux kernel uses the negative values. Besides the sources (going through like 5 include hops from /usr/include/errno.h to /usr/include/asm-generic/errno.h and /usr/include/asm-generic/errno-base.h) there’s no direct way to get the symbolic <-> numeric mapping. The hexa values commonly appear in the stack trace dumps.

symbolic dec hex neg hex comment
EPERM 1 0x01 0x..ffff Operation not permitted
ENOENT 2 0x02 0x..fffe No such file or directory
ESRCH 3 0x03 0x..fffd No such process
EINTR 4 0x04 0x..fffc Interrupted system call
EIO 5 0x05 0x..fffb I/O error
ENXIO 6 0x06 0x..fffa No such device or address
E2BIG 7 0x07 0x..fff9 Argument list too long
ENOEXEC 8 0x08 0x..fff8 Exec format error
EBADF 9 0x09 0x..fff7 Bad file number
ECHILD 10 0x0a 0x..fff6 No child processes
EAGAIN 11 0x0b 0x..fff5 Try again
ENOMEM 12 0x0c 0x..fff4 Out of memory
EACCES 13 0x0d 0x..fff3 Permission denied
EFAULT 14 0x0e 0x..fff2 Bad address
ENOTBLK 15 0x0f 0x..fff1 Block device required
EBUSY 16 0x10 0x..fff0 Device or resource busy
EEXIST 17 0x11 0x..ffef File exists
EXDEV 18 0x12 0x..ffee Cross-device link
ENODEV 19 0x13 0x..ffed No such device
ENOTDIR 20 0x14 0x..ffec Not a directory
EISDIR 21 0x15 0x..ffeb Is a directory
EINVAL 22 0x16 0x..ffea Invalid argument
ENFILE 23 0x17 0x..ffe9 File table overflow
EMFILE 24 0x18 0x..ffe8 Too many open files
ENOTTY 25 0x19 0x..ffe7 Not a typewriter
ETXTBSY 26 0x1a 0x..ffe6 Text file busy
EFBIG 27 0x1b 0x..ffe5 File too large
ENOSPC 28 0x1c 0x..ffe4 No space left on device
ESPIPE 29 0x1d 0x..ffe3 Illegal seek
EROFS 30 0x1e 0x..ffe2 Read-only file system
EMLINK 31 0x1f 0x..ffe1 Too many links
EPIPE 32 0x20 0x..ffe0 Broken pipe
EDOM 33 0x21 0x..ffdf Math argument out of domain of func
ERANGE 34 0x22 0x..ffde Math result not representable
EDEADLK 35 0x23 0x..ffdd Resource deadlock would occur
ENAMETOOLONG 36 0x24 0x..ffdc File name too long
ENOLCK 37 0x25 0x..ffdb No record locks available
ENOSYS 38 0x26 0x..ffda Function not implemented
ENOTEMPTY 39 0x27 0x..ffd9 Directory not empty
ELOOP 40 0x28 0x..ffd8 Too many symbolic links encountered
EWOULDBLOCK EAGAIN      
ENOMSG 42 0x2a 0x..ffd6 No message of desired type
EIDRM 43 0x2b 0x..ffd5 Identifier removed
ECHRNG 44 0x2c 0x..ffd4 Channel number out of range
EL2NSYNC 45 0x2d 0x..ffd3 Level 2 not synchronized
EL3HLT 46 0x2e 0x..ffd2 Level 3 halted
EL3RST 47 0x2f 0x..ffd1 Level 3 reset
ELNRNG 48 0x30 0x..ffd0 Link number out of range
EUNATCH 49 0x31 0x..ffcf Protocol driver not attached
ENOCSI 50 0x32 0x..ffce No CSI structure available
EL2HLT 51 0x33 0x..ffcd Level 2 halted
EBADE 52 0x34 0x..ffcc Invalid exchange
EBADR 53 0x35 0x..ffcb Invalid request descriptor
EXFULL 54 0x36 0x..ffca Exchange full
ENOANO 55 0x37 0x..ffc9 No anode
EBADRQC 56 0x38 0x..ffc8 Invalid request code
EBADSLT 57 0x39 0x..ffc7 Invalid slot
EDEADLOCK EDEADLK      
EBFONT 59 0x3b 0x..ffc5 Bad font file format
ENOSTR 60 0x3c 0x..ffc4 Device not a stream
ENODATA 61 0x3d 0x..ffc3 No data available
ETIME 62 0x3e 0x..ffc2 Timer expired
ENOSR 63 0x3f 0x..ffc1 Out of streams resources
ENONET 64 0x40 0x..ffc0 Machine is not on the network
ENOPKG 65 0x41 0x..ffbf Package not installed
EREMOTE 66 0x42 0x..ffbe Object is remote
ENOLINK 67 0x43 0x..ffbd Link has been severed
EADV 68 0x44 0x..ffbc Advertise error
ESRMNT 69 0x45 0x..ffbb Srmount error
ECOMM 70 0x46 0x..ffba Communication error on send
EPROTO 71 0x47 0x..ffb9 Protocol error
EMULTIHOP 72 0x48 0x..ffb8 Multihop attempted
EDOTDOT 73 0x49 0x..ffb7 RFS specific error
EBADMSG 74 0x4a 0x..ffb6 Not a data message
EOVERFLOW 75 0x4b 0x..ffb5 Value too large for defined data type
ENOTUNIQ 76 0x4c 0x..ffb4 Name not unique on network
EBADFD 77 0x4d 0x..ffb3 File descriptor in bad state
EREMCHG 78 0x4e 0x..ffb2 Remote address changed
ELIBACC 79 0x4f 0x..ffb1 Can not access a needed shared library
ELIBBAD 80 0x50 0x..ffb0 Accessing a corrupted shared library
ELIBSCN 81 0x51 0x..ffaf .lib section in a.out corrupted
ELIBMAX 82 0x52 0x..ffae Attempting to link in too many shared libraries
ELIBEXEC 83 0x53 0x..ffad Cannot exec a shared library directly
EILSEQ 84 0x54 0x..ffac Illegal byte sequence
ERESTART 85 0x55 0x..ffab Interrupted system call should be restarted
ESTRPIPE 86 0x56 0x..ffaa Streams pipe error
EUSERS 87 0x57 0x..ffa9 Too many users
ENOTSOCK 88 0x58 0x..ffa8 Socket operation on non-socket
EDESTADDRREQ 89 0x59 0x..ffa7 Destination address required
EMSGSIZE 90 0x5a 0x..ffa6 Message too long
EPROTOTYPE 91 0x5b 0x..ffa5 Protocol wrong type for socket
ENOPROTOOPT 92 0x5c 0x..ffa4 Protocol not available
EPROTONOSUPPORT 93 0x5d 0x..ffa3 Protocol not supported
ESOCKTNOSUPPORT 94 0x5e 0x..ffa2 Socket type not supported
EOPNOTSUPP 95 0x5f 0x..ffa1 Operation not supported on transport endpoint
EPFNOSUPPORT 96 0x60 0x..ffa0 Protocol family not supported
EAFNOSUPPORT 97 0x61 0x..ff9f Address family not supported by protocol
EADDRINUSE 98 0x62 0x..ff9e Address already in use
EADDRNOTAVAIL 99 0x63 0x..ff9d Cannot assign requested address
ENETDOWN 100 0x64 0x..ff9c Network is down
ENETUNREACH 101 0x65 0x..ff9b Network is unreachable
ENETRESET 102 0x66 0x..ff9a Network dropped connection because of reset
ECONNABORTED 103 0x67 0x..ff99 Software caused connection abort
ECONNRESET 104 0x68 0x..ff98 Connection reset by peer
ENOBUFS 105 0x69 0x..ff97 No buffer space available
EISCONN 106 0x6a 0x..ff96 Transport endpoint is already connected
ENOTCONN 107 0x6b 0x..ff95 Transport endpoint is not connected
ESHUTDOWN 108 0x6c 0x..ff94 Cannot send after transport endpoint shutdown
ETOOMANYREFS 109 0x6d 0x..ff93 Too many references: cannot splice
ETIMEDOUT 110 0x6e 0x..ff92 Connection timed out
ECONNREFUSED 111 0x6f 0x..ff91 Connection refused
EHOSTDOWN 112 0x70 0x..ff90 Host is down
EHOSTUNREACH 113 0x71 0x..ff8f No route to host
EALREADY 114 0x72 0x..ff8e Operation already in progress
EINPROGRESS 115 0x73 0x..ff8d Operation now in progress
ESTALE 116 0x74 0x..ff8c Stale NFS file handle
EUCLEAN 117 0x75 0x..ff8b Structure needs cleaning
ENOTNAM 118 0x76 0x..ff8a Not a XENIX named type file
ENAVAIL 119 0x77 0x..ff89 No XENIX semaphores available
EISNAM 120 0x78 0x..ff88 Is a named type file
EREMOTEIO 121 0x79 0x..ff87 Remote I/O error
EDQUOT 122 0x7a 0x..ff86 Quota exceeded
ENOMEDIUM 123 0x7b 0x..ff85 No medium found
EMEDIUMTYPE 124 0x7c 0x..ff84 Wrong medium type
ECANCELED 125 0x7d 0x..ff83 Operation Canceled
ENOKEY 126 0x7e 0x..ff82 Required key not available
EKEYEXPIRED 127 0x7f 0x..ff81 Key has expired
EKEYREVOKED 128 0x80 0x..ff80 Key has been revoked
EKEYREJECTED 129 0x81 0x..ff7f Key was rejected by service
EOWNERDEAD 130 0x82 0x..ff7e Owner died
ENOTRECOVERABLE 131 0x83 0x..ff7d State not recoverable
ERFKILL 132 0x84 0x..ff7c Operation not possible due to RF-kill
EHWPOISON 133 0x85 0x..ff7b Memory page has hardware error
ERESTARTSYS 512 0x200 0x..ff200  
ERESTARTNOINTR 513 0x201 0x..ff1ff  
ERESTARTNOHAND 514 0x202 0x..ff1fe restart if no handler..
ENOIOCTLCMD 515 0x203 0x..ff1fd No ioctl command
ERESTART_RESTARTBLOCK 516 0x204 0x..ff1fc restart by calling sys_restart_syscall
EBADHANDLE 521 0x209 0x..ff1f7 Illegal NFS file handle
ENOTSYNC 522 0x20a 0x..ff1f6 Update synchronization mismatch
EBADCOOKIE 523 0x20b 0x..ff1f5 Cookie is stale
ENOTSUPP 524 0x20c 0x..ff1f4 Operation is not supported
ETOOSMALL 525 0x20d 0x..ff1f3 Buffer or request is too small
ESERVERFAULT 526 0x20e 0x..ff1f2 An untranslatable error occurred
EBADTYPE 527 0x20f 0x..ff1f1 Type not supported by server
EJUKEBOX 528 0x210 0x..ff1f0 Request initiated, but will not complete before timeout
EIOCBQUEUED 529 0x211 0x..ff1ef iocb queued, will get completion event
EIOCBRETRY 530 0x212 0x..ff1ee iocb queued, will trigger a retry