James G. Sack (jim) wrote:
> jerry wrote:
>> As i understand it after running a command running "echo $?" will
>> respond with 0 if the command executed properly and any other number if
>> there were an error.
>>
>> I keep getting the response 130; obviously an error. Where can i find a
>> list of error codes on linux?
>
> Note that echo $? reports the exit-code returned by the last command, so
> it is important not to interpose a unrelated command (such as even an
> empty command followed by ENTER.
>
> I'm not sure why there isn't an easier way to find out, but
> less /usr/include/asm/errno.h
> let's me browse them on my system(s).
>
> man errno just gives the symbolic names
> man strerror _ought_ to give a mapping, I suppose
>
> There is a perl module Errno.pm, but I haven't figured out how to use it.
>
> It's not the most convenient, but you can use python to translate a
> number to a posix name and then use man errno to get descriptive info
> (sheesh!)
>
> python -c'import errno;print errno.errorcode[7]'
> But this only includes _standard_ errors up to (near) 127.
>
>
> I thought that error codes over 128 meant something special (my
> asm/errno.h stops at 124), but I can't recall what -- can somebody help
> on this?
>
> Anyway, here's a quickie c proglet to play with.
> Cut and save as strerror.c, and build it from the command line in the
> directory where you saved it with the simple default make command
>
> make strerror
>
> That will will turn strerror.c into an executable strerror)
>
> When I run this on my system, I get
> strerror(130) returns 'Owner died'
> ..but I'm still here!, so I think it's safe <heh>
>
> ===program-code===
> #include <stdio.h>
> //#include <errno.h>
> #include <string.h>
>
> #define BLEN 31
>
> int main(){
> char ibuf[BLEN+1];
> int err;
> while (1){
> printf("\nEnter error number to lookup: (Just Enter to quit).. ? ");
> fgets(ibuf, BLEN, stdin);
> err = atoi(ibuf);
> if (!err)
> return 0;
> printf("strerror(%d) returns '%s'\n", err, strerror(err));
> }
> }
> ===end code=======
>
> Man it's been soooo long since I wrote any c. The above is probably not
> up to best practice these days. Comments welcome
>
> (I'd really prefer to write it in perl or python. Anybody help?)
>
Of course, this error string lookup assumes that the application has
exited with a return code matching whatever the libc strerror knows
about, and as cdl has observed in an intervening post, the app prog can
perform any exit(rand()) it feels like.
So the output may or may not actually be meaningful -- ask the
application provider (or read the source), I guess.
I suppose that's why there's NO generally available utility like my
wonderful code example -- it implies more than can be reasonably expected.
Caveat emptor (or some such..)
..jim
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