Re^2: how does '2>&1' work ?

But I do encounter such a question:

case 1:

use strict; my $cmd = "dumpcap -i eth0 -b duration:10 -w \\media\\Work\\abc.pcap"; `$cmd`

"dumpcap" itself will print some infomation, if I add 2>&1 behind $cmd, such as `$cmd 2>&1`, no infomation displayed. But if I do not add 2>&1, information do displays

in another case, If I change $cmd to :

my $cmd = "ifconfig";

There is no information displayed in shell no matter If I add 2>&1 or not

Why is this difference ?

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Re^3: how does '2>&1' work ? by ikegami (Patriarch) on Feb 23, 2011 at 06:10 UTC
That means that dumpcap printed some information to STDERR and ifconfig didn't.	[reply]
Re^4: how does '2>&1' work ? by wildnature (Novice) on Feb 23, 2011 at 07:19 UTC
Great! I got it. Thanks a lot :)	[reply]
Re^3: how does '2>&1' work ? by Anonymous Monk on Feb 23, 2011 at 05:01 UTC
Why is this difference ? Why is dumpcap different from ifconfig? Because it wants to be different?	[reply]