How to convert errno in UNIX to corresponding string?
https://stackoverflow.com/questions/1546882
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Is there any function in UNIX to the convert errno to its corresponding string for e.g. EIDRM to "EIDRM". Its very annoying to debug to check for errors with these integer errnos.
Solution
strerror() should do it. http://linux.die.net/man/3/strerror
FYI, so that you can find these things more easily, yourself: If you type man errno (or whatever function you're investigating), and look at the very bottom of the man page, you'll see a list of related functions. If you man each of those (taking a guess about which one(s) to do first based on their names) you'll often find the answer to similar questions.
OTHER TIPS
Just another solution that solves exactly the problem you have, but in Python instead of C:
>>> import errno
>>> errno.errorcode[errno.EIDRM]
'EIDRM'
There's now an errno utility distributed with the moreutils package.
I'm not sure about such enum-style names, but for debugging and error reporting purposes you may use perror(3) or strerror(3) C functions that return a human-readable representation of the error code. Please refer to the man pages for more details.
If you do indeed want EIDRM and not its error string: no. However, on OpenBSD,
man errno|egrep ' [0-9]+ E[A-Z]+'|sed 's/^ *//'|cut -d' ' -f1,2
prints out a nice table of "...\n89 EIDM\n..." that you can convert further into a data structure for the programming language that you'd like to have this function in.
There is no standard function to do this in UNIX.
But I recently wrote the errnoname library that has an errnoname function which does exactly this.
strerror (also strerror_r, strerror_l, perror) print a "human friendly" hint about what the error was, but their outputs are
- usually undocumented,
- not standardized,
- not guaranteed to follow any constrains on length or format,
- often different depending on locale settings, and
- do not always make sense in all situations (for example they tend to print
File existsforEEXIST, even though that error is often returned for things that are not files).
Which means that they are superficially user-friendly but
- other code cannot parse them as reliably (worse for automation, monitoring, scripting, wrapper programs, etc),
- can mislead in the edge cases, and
- get in the way of technical experienced users.
Ironically there is nothing preventing those functions from just using the errno symbolic name as their error string in all circumstances - it would be within the letter of the standard, especially if they only did it for a specific locale, like the special C locale. But no libc I know of does this.
Anyway, since my errnoname is released under the "Zero-Clause BSD license" (0BSD), which is a permissive license, or more accurately a public-domain-equivalent license, you can do whatever you want with it.
Below is a direct copy-paste of the function from my library, so that this answer can stand alone. Couple of notes:
This covers all or most of
errnonames for Linux, Darwin (Mac OS X and iOS X), FreeBSD, NetBSD, OpenBSD, DragonflyBSD, and several closed source Unixes, as of start of August 2019.It returns a
NULLpointer if you give it anerrnovalue it does not know the name of.
#include <errno.h>
char const * errnoname(int errno_)
{
switch(errno_)
{
#ifdef E2BIG
case E2BIG: return "E2BIG";
#endif
#ifdef EACCES
case EACCES: return "EACCES";
#endif
#ifdef EADDRINUSE
case EADDRINUSE: return "EADDRINUSE";
#endif
#ifdef EADDRNOTAVAIL
case EADDRNOTAVAIL: return "EADDRNOTAVAIL";
#endif
#ifdef EADI
case EADI: return "EADI";
#endif
#ifdef EADV
case EADV: return "EADV";
#endif
#ifdef EAFNOSUPPORT
case EAFNOSUPPORT: return "EAFNOSUPPORT";
#endif
#ifdef EAGAIN
case EAGAIN: return "EAGAIN";
#endif
#ifdef EAIO
case EAIO: return "EAIO";
#endif
#ifdef EALIGN
case EALIGN: return "EALIGN";
#endif
#ifdef EALREADY
case EALREADY: return "EALREADY";
#endif
#ifdef EASYNC
case EASYNC: return "EASYNC";
#endif
#ifdef EAUTH
case EAUTH: return "EAUTH";
#endif
#ifdef EBADARCH
case EBADARCH: return "EBADARCH";
#endif
#ifdef EBADE
case EBADE: return "EBADE";
#endif
#ifdef EBADEXEC
case EBADEXEC: return "EBADEXEC";
#endif
#ifdef EBADF
case EBADF: return "EBADF";
#endif
#ifdef EBADFD
case EBADFD: return "EBADFD";
#endif
#ifdef EBADMACHO
case EBADMACHO: return "EBADMACHO";
#endif
#ifdef EBADMSG
case EBADMSG: return "EBADMSG";
#endif
#ifdef EBADR
case EBADR: return "EBADR";
#endif
#ifdef EBADRPC
case EBADRPC: return "EBADRPC";
#endif
#ifdef EBADRQC
case EBADRQC: return "EBADRQC";
#endif
#ifdef EBADSLT
case EBADSLT: return "EBADSLT";
#endif
#ifdef EBADVER
case EBADVER: return "EBADVER";
#endif
#ifdef EBFONT
case EBFONT: return "EBFONT";
#endif
#ifdef EBUSY
case EBUSY: return "EBUSY";
#endif
#ifdef ECANCELED
case ECANCELED: return "ECANCELED";
#endif
#if defined(ECANCELLED) && (!defined(ECANCELED) || ECANCELLED != ECANCELED)
case ECANCELLED: return "ECANCELLED";
#endif
#ifdef ECAPMODE
case ECAPMODE: return "ECAPMODE";
#endif
#ifdef ECHILD
case ECHILD: return "ECHILD";
#endif
#ifdef ECHRNG
case ECHRNG: return "ECHRNG";
#endif
#ifdef ECKPT
case ECKPT: return "ECKPT";
#endif
#ifdef ECLONEME
case ECLONEME: return "ECLONEME";
#endif
#ifdef ECOMM
case ECOMM: return "ECOMM";
#endif
#ifdef ECONFIG
case ECONFIG: return "ECONFIG";
#endif
#ifdef ECONNABORTED
case ECONNABORTED: return "ECONNABORTED";
#endif
#ifdef ECONNREFUSED
case ECONNREFUSED: return "ECONNREFUSED";
#endif
#ifdef ECONNRESET
case ECONNRESET: return "ECONNRESET";
#endif
#ifdef ECORRUPT
case ECORRUPT: return "ECORRUPT";
#endif
#ifdef ECVCERORR
case ECVCERORR: return "ECVCERORR";
#endif
#ifdef ECVPERORR
case ECVPERORR: return "ECVPERORR";
#endif
#ifdef EDEADLK
case EDEADLK: return "EDEADLK";
#endif
#if defined(EDEADLOCK) && (!defined(EDEADLK) || EDEADLOCK != EDEADLK)
case EDEADLOCK: return "EDEADLOCK";
#endif
#ifdef EDESTADDREQ
case EDESTADDREQ: return "EDESTADDREQ";
#endif
#ifdef EDESTADDRREQ
case EDESTADDRREQ: return "EDESTADDRREQ";
#endif
#ifdef EDEVERR
case EDEVERR: return "EDEVERR";
#endif
#ifdef EDIRIOCTL
case EDIRIOCTL: return "EDIRIOCTL";
#endif
#ifdef EDIRTY
case EDIRTY: return "EDIRTY";
#endif
#ifdef EDIST
case EDIST: return "EDIST";
#endif
#ifdef EDOM
case EDOM: return "EDOM";
#endif
#ifdef EDOOFUS
case EDOOFUS: return "EDOOFUS";
#endif
#ifdef EDOTDOT
case EDOTDOT: return "EDOTDOT";
#endif
#ifdef EDQUOT
case EDQUOT: return "EDQUOT";
#endif
#ifdef EDUPFD
case EDUPFD: return "EDUPFD";
#endif
#ifdef EDUPPKG
case EDUPPKG: return "EDUPPKG";
#endif
#ifdef EEXIST
case EEXIST: return "EEXIST";
#endif
#ifdef EFAIL
case EFAIL: return "EFAIL";
#endif
#ifdef EFAULT
case EFAULT: return "EFAULT";
#endif
#ifdef EFBIG
case EFBIG: return "EFBIG";
#endif
#ifdef EFORMAT
case EFORMAT: return "EFORMAT";
#endif
#ifdef EFSCORRUPTED
case EFSCORRUPTED: return "EFSCORRUPTED";
#endif
#ifdef EFTYPE
case EFTYPE: return "EFTYPE";
#endif
#ifdef EHOSTDOWN
case EHOSTDOWN: return "EHOSTDOWN";
#endif
#ifdef EHOSTUNREACH
case EHOSTUNREACH: return "EHOSTUNREACH";
#endif
#ifdef EHWPOISON
case EHWPOISON: return "EHWPOISON";
#endif
#ifdef EIDRM
case EIDRM: return "EIDRM";
#endif
#ifdef EILSEQ
case EILSEQ: return "EILSEQ";
#endif
#ifdef EINIT
case EINIT: return "EINIT";
#endif
#ifdef EINPROG
case EINPROG: return "EINPROG";
#endif
#ifdef EINPROGRESS
case EINPROGRESS: return "EINPROGRESS";
#endif
#ifdef EINTEGRITY
case EINTEGRITY: return "EINTEGRITY";
#endif
#ifdef EINTR
case EINTR: return "EINTR";
#endif
#ifdef EINVAL
case EINVAL: return "EINVAL";
#endif
#ifdef EIO
case EIO: return "EIO";
#endif
#ifdef EIPSEC
case EIPSEC: return "EIPSEC";
#endif
#ifdef EISCONN
case EISCONN: return "EISCONN";
#endif
#ifdef EISDIR
case EISDIR: return "EISDIR";
#endif
#ifdef EISNAM
case EISNAM: return "EISNAM";
#endif
#ifdef EJUSTRETURN
case EJUSTRETURN: return "EJUSTRETURN";
#endif
#ifdef EKEEPLOOKING
case EKEEPLOOKING: return "EKEEPLOOKING";
#endif
#ifdef EKEYEXPIRED
case EKEYEXPIRED: return "EKEYEXPIRED";
#endif
#ifdef EKEYREJECTED
case EKEYREJECTED: return "EKEYREJECTED";
#endif
#ifdef EKEYREVOKED
case EKEYREVOKED: return "EKEYREVOKED";
#endif
#ifdef EL2HLT
case EL2HLT: return "EL2HLT";
#endif
#ifdef EL2NSYNC
case EL2NSYNC: return "EL2NSYNC";
#endif
#ifdef EL3HLT
case EL3HLT: return "EL3HLT";
#endif
#ifdef EL3RST
case EL3RST: return "EL3RST";
#endif
#ifdef ELIBACC
case ELIBACC: return "ELIBACC";
#endif
#ifdef ELIBBAD
case ELIBBAD: return "ELIBBAD";
#endif
#ifdef ELIBEXEC
case ELIBEXEC: return "ELIBEXEC";
#endif
#ifdef ELIBMAX
case ELIBMAX: return "ELIBMAX";
#endif
#ifdef ELIBSCN
case ELIBSCN: return "ELIBSCN";
#endif
#ifdef ELNRNG
case ELNRNG: return "ELNRNG";
#endif
#ifdef ELOCKUNMAPPED
case ELOCKUNMAPPED: return "ELOCKUNMAPPED";
#endif
#ifdef ELOOP
case ELOOP: return "ELOOP";
#endif
#ifdef EMEDIA
case EMEDIA: return "EMEDIA";
#endif
#ifdef EMEDIUMTYPE
case EMEDIUMTYPE: return "EMEDIUMTYPE";
#endif
#ifdef EMFILE
case EMFILE: return "EMFILE";
#endif
#ifdef EMLINK
case EMLINK: return "EMLINK";
#endif
#ifdef EMOUNTEXIT
case EMOUNTEXIT: return "EMOUNTEXIT";
#endif
#ifdef EMOVEFD
case EMOVEFD: return "EMOVEFD";
#endif
#ifdef EMSGSIZE
case EMSGSIZE: return "EMSGSIZE";
#endif
#ifdef EMTIMERS
case EMTIMERS: return "EMTIMERS";
#endif
#ifdef EMULTIHOP
case EMULTIHOP: return "EMULTIHOP";
#endif
#ifdef ENAMETOOLONG
case ENAMETOOLONG: return "ENAMETOOLONG";
#endif
#ifdef ENAVAIL
case ENAVAIL: return "ENAVAIL";
#endif
#ifdef ENEEDAUTH
case ENEEDAUTH: return "ENEEDAUTH";
#endif
#ifdef ENETDOWN
case ENETDOWN: return "ENETDOWN";
#endif
#ifdef ENETRESET
case ENETRESET: return "ENETRESET";
#endif
#ifdef ENETUNREACH
case ENETUNREACH: return "ENETUNREACH";
#endif
#ifdef ENFILE
case ENFILE: return "ENFILE";
#endif
#ifdef ENFSREMOTE
case ENFSREMOTE: return "ENFSREMOTE";
#endif
#ifdef ENOANO
case ENOANO: return "ENOANO";
#endif
#ifdef ENOATTR
case ENOATTR: return "ENOATTR";
#endif
#ifdef ENOBUFS
case ENOBUFS: return "ENOBUFS";
#endif
#ifdef ENOCONNECT
case ENOCONNECT: return "ENOCONNECT";
#endif
#ifdef ENOCSI
case ENOCSI: return "ENOCSI";
#endif
#ifdef ENODATA
case ENODATA: return "ENODATA";
#endif
#ifdef ENODEV
case ENODEV: return "ENODEV";
#endif
#ifdef ENOENT
case ENOENT: return "ENOENT";
#endif
#ifdef ENOEXEC
case ENOEXEC: return "ENOEXEC";
#endif
#ifdef ENOIOCTL
case ENOIOCTL: return "ENOIOCTL";
#endif
#ifdef ENOKEY
case ENOKEY: return "ENOKEY";
#endif
#ifdef ENOLCK
case ENOLCK: return "ENOLCK";
#endif
#ifdef ENOLINK
case ENOLINK: return "ENOLINK";
#endif
#ifdef ENOLOAD
case ENOLOAD: return "ENOLOAD";
#endif
#ifdef ENOMATCH
case ENOMATCH: return "ENOMATCH";
#endif
#ifdef ENOMEDIUM
case ENOMEDIUM: return "ENOMEDIUM";
#endif
#ifdef ENOMEM
case ENOMEM: return "ENOMEM";
#endif
#ifdef ENOMSG
case ENOMSG: return "ENOMSG";
#endif
#ifdef ENONET
case ENONET: return "ENONET";
#endif
#ifdef ENOPKG
case ENOPKG: return "ENOPKG";
#endif
#ifdef ENOPOLICY
case ENOPOLICY: return "ENOPOLICY";
#endif
#ifdef ENOPROTOOPT
case ENOPROTOOPT: return "ENOPROTOOPT";
#endif
#ifdef ENOREG
case ENOREG: return "ENOREG";
#endif
#ifdef ENOSPC
case ENOSPC: return "ENOSPC";
#endif
#ifdef ENOSR
case ENOSR: return "ENOSR";
#endif
#ifdef ENOSTR
case ENOSTR: return "ENOSTR";
#endif
#ifdef ENOSYM
case ENOSYM: return "ENOSYM";
#endif
#ifdef ENOSYS
case ENOSYS: return "ENOSYS";
#endif
#ifdef ENOTACTIVE
case ENOTACTIVE: return "ENOTACTIVE";
#endif
#ifdef ENOTBLK
case ENOTBLK: return "ENOTBLK";
#endif
#ifdef ENOTCAPABLE
case ENOTCAPABLE: return "ENOTCAPABLE";
#endif
#ifdef ENOTCONN
case ENOTCONN: return "ENOTCONN";
#endif
#ifdef ENOTDIR
case ENOTDIR: return "ENOTDIR";
#endif
#ifdef ENOTEMPTY
case ENOTEMPTY: return "ENOTEMPTY";
#endif
#ifdef ENOTNAM
case ENOTNAM: return "ENOTNAM";
#endif
#ifdef ENOTREADY
case ENOTREADY: return "ENOTREADY";
#endif
#ifdef ENOTRECOVERABLE
case ENOTRECOVERABLE: return "ENOTRECOVERABLE";
#endif
#ifdef ENOTRUST
case ENOTRUST: return "ENOTRUST";
#endif
#ifdef ENOTSOCK
case ENOTSOCK: return "ENOTSOCK";
#endif
#ifdef ENOTSUP
case ENOTSUP: return "ENOTSUP";
#endif
#ifdef ENOTTY
case ENOTTY: return "ENOTTY";
#endif
#ifdef ENOTUNIQ
case ENOTUNIQ: return "ENOTUNIQ";
#endif
#ifdef ENOUNLD
case ENOUNLD: return "ENOUNLD";
#endif
#ifdef ENOUNREG
case ENOUNREG: return "ENOUNREG";
#endif
#ifdef ENXIO
case ENXIO: return "ENXIO";
#endif
#ifdef EOPCOMPLETE
case EOPCOMPLETE: return "EOPCOMPLETE";
#endif
#if defined(EOPNOTSUPP) && (!defined(ENOTSUP) || EOPNOTSUPP != ENOTSUP)
case EOPNOTSUPP: return "EOPNOTSUPP";
#endif
#ifdef EOVERFLOW
case EOVERFLOW: return "EOVERFLOW";
#endif
#ifdef EOWNERDEAD
case EOWNERDEAD: return "EOWNERDEAD";
#endif
#ifdef EPASSTHROUGH
case EPASSTHROUGH: return "EPASSTHROUGH";
#endif
#ifdef EPATHREMOTE
case EPATHREMOTE: return "EPATHREMOTE";
#endif
#ifdef EPERM
case EPERM: return "EPERM";
#endif
#ifdef EPFNOSUPPORT
case EPFNOSUPPORT: return "EPFNOSUPPORT";
#endif
#ifdef EPIPE
case EPIPE: return "EPIPE";
#endif
#ifdef EPOWERF
case EPOWERF: return "EPOWERF";
#endif
#ifdef EPROCLIM
case EPROCLIM: return "EPROCLIM";
#endif
#ifdef EPROCUNAVAIL
case EPROCUNAVAIL: return "EPROCUNAVAIL";
#endif
#ifdef EPROGMISMATCH
case EPROGMISMATCH: return "EPROGMISMATCH";
#endif
#ifdef EPROGUNAVAIL
case EPROGUNAVAIL: return "EPROGUNAVAIL";
#endif
#ifdef EPROTO
case EPROTO: return "EPROTO";
#endif
#ifdef EPROTONOSUPPORT
case EPROTONOSUPPORT: return "EPROTONOSUPPORT";
#endif
#ifdef EPROTOTYPE
case EPROTOTYPE: return "EPROTOTYPE";
#endif
#ifdef EPWROFF
case EPWROFF: return "EPWROFF";
#endif
#ifdef EQFULL
case EQFULL: return "EQFULL";
#endif
#ifdef EQSUSPENDED
case EQSUSPENDED: return "EQSUSPENDED";
#endif
#ifdef ERANGE
case ERANGE: return "ERANGE";
#endif
#ifdef ERECYCLE
case ERECYCLE: return "ERECYCLE";
#endif
#ifdef EREDRIVEOPEN
case EREDRIVEOPEN: return "EREDRIVEOPEN";
#endif
#ifdef EREFUSED
case EREFUSED: return "EREFUSED";
#endif
#ifdef ERELOC
case ERELOC: return "ERELOC";
#endif
#ifdef ERELOCATED
case ERELOCATED: return "ERELOCATED";
#endif
#ifdef ERELOOKUP
case ERELOOKUP: return "ERELOOKUP";
#endif
#ifdef EREMCHG
case EREMCHG: return "EREMCHG";
#endif
#ifdef EREMDEV
case EREMDEV: return "EREMDEV";
#endif
#ifdef EREMOTE
case EREMOTE: return "EREMOTE";
#endif
#ifdef EREMOTEIO
case EREMOTEIO: return "EREMOTEIO";
#endif
#ifdef EREMOTERELEASE
case EREMOTERELEASE: return "EREMOTERELEASE";
#endif
#ifdef ERESTART
case ERESTART: return "ERESTART";
#endif
#ifdef ERFKILL
case ERFKILL: return "ERFKILL";
#endif
#ifdef EROFS
case EROFS: return "EROFS";
#endif
#ifdef ERPCMISMATCH
case ERPCMISMATCH: return "ERPCMISMATCH";
#endif
#ifdef ESAD
case ESAD: return "ESAD";
#endif
#ifdef ESHLIBVERS
case ESHLIBVERS: return "ESHLIBVERS";
#endif
#ifdef ESHUTDOWN
case ESHUTDOWN: return "ESHUTDOWN";
#endif
#ifdef ESOCKTNOSUPPORT
case ESOCKTNOSUPPORT: return "ESOCKTNOSUPPORT";
#endif
#ifdef ESOFT
case ESOFT: return "ESOFT";
#endif
#ifdef ESPIPE
case ESPIPE: return "ESPIPE";
#endif
#ifdef ESRCH
case ESRCH: return "ESRCH";
#endif
#ifdef ESRMNT
case ESRMNT: return "ESRMNT";
#endif
#ifdef ESTALE
case ESTALE: return "ESTALE";
#endif
#ifdef ESTART
case ESTART: return "ESTART";
#endif
#ifdef ESTRPIPE
case ESTRPIPE: return "ESTRPIPE";
#endif
#ifdef ESYSERROR
case ESYSERROR: return "ESYSERROR";
#endif
#ifdef ETIME
case ETIME: return "ETIME";
#endif
#ifdef ETIMEDOUT
case ETIMEDOUT: return "ETIMEDOUT";
#endif
#ifdef ETOOMANYREFS
case ETOOMANYREFS: return "ETOOMANYREFS";
#endif
#ifdef ETXTBSY
case ETXTBSY: return "ETXTBSY";
#endif
#ifdef EUCLEAN
case EUCLEAN: return "EUCLEAN";
#endif
#ifdef EUNATCH
case EUNATCH: return "EUNATCH";
#endif
#ifdef EUSERS
case EUSERS: return "EUSERS";
#endif
#ifdef EVERSION
case EVERSION: return "EVERSION";
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || EWOULDBLOCK != EAGAIN)
case EWOULDBLOCK: return "EWOULDBLOCK";
#endif
#ifdef EWRONGFS
case EWRONGFS: return "EWRONGFS";
#endif
#ifdef EWRPROTECT
case EWRPROTECT: return "EWRPROTECT";
#endif
#ifdef EXDEV
case EXDEV: return "EXDEV";
#endif
#ifdef EXFULL
case EXFULL: return "EXFULL";
#endif
}
return 0;
}
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