Ottenere il valore di ritorno di un comando eseguito utilizzando backticks in Perl

Question

posso fare quanto segue in bash:

output=`command` 
retcode=$? 

Esiste un modo di fare lo stesso in Perl? Qualcosa del genere:

$output=`command` 
$retcode=??? 

Answer 1

È possibile leggere la variabile $? (come nella shell). Da man perlvar

$?  The status returned by the last pipe close, backtick ("``") command, successful call to wait() or waitpid(), or from the 
       system() operator. This is just the 16-bit status word returned by the traditional Unix wait() system call (or else is made up 
       to look like it). Thus, the exit value of the subprocess is really ("$? >> 8"), and "$? & 127" gives which signal, if any, the 
       process died from, and "$? & 128" reports whether there was a core dump. (Mnemonic: similar to sh and ksh.) 

       Additionally, if the "h_errno" variable is supported in C, its value is returned via $? if any "gethost*()" function fails. 

       If you have installed a signal handler for "SIGCHLD", the value of $? will usually be wrong outside that handler. 

       Inside an "END" subroutine $? contains the value that is going to be given to "exit()". You can modify $? in an "END" 
       subroutine to change the exit status of your program. For example: 

        END { 
         $? = 1 if $? == 255; # die would make it 255 
        } 

       Under VMS, the pragma "use vmsish 'status'" makes $? reflect the actual VMS exit status, instead of the default emulation of 
       POSIX status; see "$?" in perlvms for details. 

       Also see "Error Indicators". 

Answer 2

E poiché Perl 5.10, hai anche ${^CHILD_ERROR_NATIVE}.

Da http://perldoc.perl.org/perl5100delta.html#New-internal-variables:

${^CHILD_ERROR_NATIVE}

Questa variabile indica lo stato nativo restituito dal l'ultimo tubo di chiusura, comando backtick, chiamata riuscita ad aspettare() o waitpid(), oppure dal operatore di sistema(). Vedi perlvar per i dettagli.