Re^4: Autoflush fails

Really appreciate your help :-)

The results of "sudo tcpdump" are redirected to STDOUT right away.

,"sudo /usr/sbin/tcpdump -i eth3 host 226.1.109.109 2>
+/dev/null"
[download]

However, the results are buffered if I pipe it to "perl -pe 1"

,"sudo /usr/sbin/tcpdump -i eth3 host 226.1.109.109 2>
+/dev/null |  perl -pe 1"
[download]

Any alternative to a file handle to get the sudo resluts from a pipe?

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Re^5: Autoflush fails by Anonymous Monk on May 31, 2012 at 05:31 UTC
However, the results are buffered if I pipe it to "perl -pe 1" You'll find they're probably buffered if you pipe to anything ( even cat ) So the solution is to ddg://tcpdump buffered and find tcpdump: Re: pipeline buffering which says if you don't specify -w, -U means "flush the standard output after the information for each packet is printed" So there you have it, install sufficiently modern version of tcpdump that comes with -U option that flushes more often FYI there also exists pcapdump, Net::Pcap::Easy... Tutorials: Network Programming: Perl and Net::Pcap	[reply]

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Re^5: Autoflush fails
by Anonymous Monk on May 31, 2012 at 05:31 UTC

However, the results are buffered if I pipe it to "perl -pe 1"

You'll find they're probably buffered if you pipe to anything ( even cat )

if you don't specify -w, -U means "flush the standard output after the information for each packet is printed"

So there you have it, install sufficiently modern version of tcpdump that comes with -U option that flushes more often