On Thu, Mar 21, 2013 at 6:41 PM, Charles DeRykus <dery...@gmail.com> wrote:
> On Thu, Mar 21, 2013 at 3:12 PM, Dominik Danter <domi...@foop.at> wrote:
>> Hi I just don't understand the perlfaq example. All I want is to capture
>> output
>> of an external command's stdout and stderr. Here is what I've tried:
>>
>>
>> sub get_exit() {
>> my ($exit_status, $std_out, $std_err) = @_;
>> my %error_codes = (
>> 1024 => 'uid already exists',
>> 256 => 'not root',
>> 0 => 'success',
>> );
>> my $message = $error_codes{$exit_status};
>> return {
>> message => (defined $message ? $message : 'unknown exit status'),
>> exit_status => $exit_status,
>> std_out => (defined $std_out ? $std_out : 'no standard output
>> produced'),
>> std_err => (defined $std_err ? $std_err : 'no error output
>> produced'),
>> };
>> }
>>
>> sub change_id {
>> my %command = (
>> uid => 'usermod --uid',
>> gid => 'usermod --gid',
>> );
>> my ($type, $username, $new_id) = @_;
>> my ($std_in, $std_out, $std_err, $exit_status);
>> eval {
>> my $pid = open3($std_in, $std_out, $std_err,
>> "$command{$type} $new_id $username");
>> waitpid( $pid, 1);
>> $exit_status = $? >> 8;
>> };
>> return &get_exit($exit_status, $std_out, $std_err );
>> }
>>
>>
>> print Dumper(user::change_id('uid','bla',997));
>>
>>
>> Here is my output:
>> Use of uninitialized value $exit_status in hash element at user.pm line 31.
>> $VAR1 = {
>> 'std_err' => 'no error output produced',
>> 'std_out' => \*Symbol::GEN1,
>> 'exit_status' => undef,
>> 'message' => 'unknown exit status'
>> };
>>
>>
>> The command should fail since it lacks required permission, but I'd like to
>> handle the error messages gracefully.
>
> waitpid( $pid, 1);
> ^^^
>
> This looks amiss. Normally, it's waitpid($pid,0) for a blocking
> wait or maybe POSIX's WNOHANG. for an async wait. See
> perldoc -f waitpid.
>
> --
> Charles DeRykus.
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