Make "-q" suppress packet printing when you're reading a capture file

and not writing to another capture file, for use with "-z" options.

Note that "-z proto" *doesn't* print statistics at the end - it modifies
the packet summary output.

Note that on at least some BSDs the "status" character is set to "off"
by default, so you have to set it explicitly in order to be able to ^T
an application such as Tethereal.

svn path=/trunk/; revision=11038

1 files changed, 25 insertions, 6 deletions

diff --git a/doc/tethereal.pod b/doc/tethereal.pod
index 80619a9e22..a5978f5237 100644
--- a/doc/tethereal.pod
+++ b/doc/tethereal.pod
@@ -397,11 +397,18 @@ machine.
 
 =item -q
 
-Don't display the continuous count of packets captured that is normally
-shown when saving a capture to a file; instead, just display, at the end
-of the capture, a count of packets captured.  On systems that support
-the SIGINFO signal, such as various BSDs, typing your "status" character
-(typically control-T) will cause the current count to be displayed.
+When capturing packets, don't display the continuous count of packets
+captured that is normally shown when saving a capture to a file;
+instead, just display, at the end of the capture, a count of packets
+captured.  On systems that support the SIGINFO signal, such as various
+BSDs, typing your "status" character (typically control-T, although it
+might be set to "disabled" by default on at least some BSDs, so you'd
+have to explicitly set it to use it) will cause the current count to be
+displayed.
+
+When reading a capture file, don't print packet information; this is
+useful if you're using a B<-z> flag to calculate statistics and don't
+want the packet information printed, just the statistics.
 
 =item -r
 
@@ -467,7 +474,19 @@ reported by B<-L> are the values that can be used.
 =item -z
 
 Get B<Tethereal> to collect various types of statistics and display the result
-after finishing reading the capture file.
+after finishing reading the capture file.  Use the B<-q> flag if you're
+reading a capture file and only want the statistics printed, not any
+per-packet information.
+
+Note that the B<-z proto> option is different - it doesn't cause
+statistics to be gathered and printed when the capture is complete, it
+modifies the regular packet summary output to include the values of
+fields specified with the option.  Therefore you must not use the B<-q>
+option, as that option would suppress the printing of the regular packet
+summary output, and must also not use the B<-V> option, as that would
+cause packet detail information rather than packet summary information
+to be printed.
+
 Currently implemented statistics are:
 
 B<-z> dcerpc,rtt,I<uuid>,I<major>.I<minor>[,I<filter>]