perl脚本中运行含有管道的系统命令时，不能将错误输出重定向到文本

[bu110]

我有一段perl脚本如下：
while(1)
{
my @i = ();
my $command = <FH>;
if(not defined ($command))
{
last;
}
chomp($command);
print RESULT "$command\n";
@i = `$command 2>&1`;
print RESULT @i;
}
FH和RESULT 都是文件句柄，
结果文件：
cat /etc/opasswd1
cat: /etc/opasswd1: No such file or directory
cat /etc/opasswd1 | grep -v "^#"

好像命令行中不加管道就能将标准输出打印到文本中，加了管道就不能输出到文本中，但是会打到屏幕上，
请高手帮忙看下，谢谢！

[bu110]

当命令中文件存在的时候，能正确输出到文本，如下：
cat /etc/pam.d/su | grep -v "^#"
auth sufficient pam_rootok.so
auth sufficient pam_wheel.so trust use_uid

[bugs2k]

Because backticks do not affect standard error, use shell file descriptor syntax (assuming the shell supports this) if you care to address this. To capture a command's STDERR and STDOUT together:

$output = `cmd 2>&1`;

To capture a command's STDOUT but discard its STDERR:

$output = `cmd 2>/dev/null`;

To capture a command's STDERR but discard its STDOUT (ordering is important here):

$output = `cmd 2>&1 1>/dev/null`;

To exchange a command's STDOUT and STDERR in order to capture the STDERR but leave its STDOUT to come out the old STDERR:

$output = `cmd 3>&1 1>&2 2>&3 3>&-`;

[bu110]

感谢楼上的回答，但是还是没有解决我的问题！

[bu110]

自己搞定，添加代码如下：
open (RESULT,">$r_file");
open STDERR, ">&RESULT";
while(1)
{
my @i = ();
my $command = <FH>;
if(not defined ($command))
{
last;
}
chomp($command);
print RESULT "$command\n";
@i = `$command 2>&1`;
print RESULT @i;
}
close STDERR;
close RESULT;