This does not delete the first line of input. It works non-destructively
common options are:
-nc do not overwrite existing files
-O filename one single filename for all of the downloads from one URL
Hi all....
I was wondering if there is a lot of differences between /bash and ksh programming.
Im learning about bash programming, but all what I had read in this forum, points me to learn more about ksh over bash. Is that right and why?
Unfortunately, I can’t write ksh progs on my work,... (2 Replies)
how to i grep a keyword which ignore upper case or lower case.
for an example :
user enter CoUcH
and the grep also can grep couch which in text.txt although upper or loever case is different .. how to do that ?
any idea? (1 Reply)
Write a Shell script to analyse the disk usage of students in a particular class.
The program should allow the user running the script to input the particular class name (group name) as an argument to the script.
The script should create a file called “logfile” in the home directory of the user... (2 Replies)
I have inherited a C++ program which does not manage it's memory at all. It has a whole bunch of 'new' variables without many deletes. I believe it was the programmers intent to let the OS clean up.
Correct me if I am wrong, but I believe the unix/linux systems clean up after the program... (1 Reply)
I am going through the examples in the book "Pro Bash Programing" which is quite a good book on bash programing. Just a word of warning about the example script called sa that simply shows command line arguments. In CentOS 5.5 there is a program called sa already on the system. Boy did that throw... (0 Replies)
Please take a look I am stuck on step 4
1. The problem statement, all variables and given/known data:
#!/bin/bash
### ULI101 - ASSIGNMENT #2 (PART A) - DUE DATE Wed, Aug 3, 2011, before 12 midnight.
###====================================================================================
###... (13 Replies)
Hi All,
I need to place a ctrl-c interrupt in a bash script, there is no other way, it has to be done :)
can someone please advise how would I go about this?
i want to use ctrl c in below code, after the code excution of just 1 min or 1sec
java Cspsamp 111.19.5.172 7025 rd1... (6 Replies)
I am going to provide a chunks of codes that I do not understand. Please help with them in a layman's terms.
1) ${DEBUG:-0}
--------------------------------------------------------------------------
2) print "${1}"
... (7 Replies)
Hi! I'm new in bash programming and I need to make an script that reads a txt file line by line (every line is like "Name;FirstLastName;SecondLastName;Sex") and has to give every student 3 random marks, its average and add a counter if they are male/female and if they passed. I've been trying with... (4 Replies)
Discussion started by: HeartHacker
4 Replies
LEARN ABOUT X11R4
pcap_dispatch
PCAP_LOOP(3PCAP)PCAP_LOOP(3PCAP)NAME
pcap_loop, pcap_dispatch - process packets from a live capture or savefile
SYNOPSIS
#include <pcap/pcap.h>
typedef void (*pcap_handler)(u_char *user, const struct pcap_pkthdr *h,
const u_char *bytes);
int pcap_loop(pcap_t *p, int cnt,
pcap_handler callback, u_char *user);
int pcap_dispatch(pcap_t *p, int cnt,
pcap_handler callback, u_char *user);
DESCRIPTION
pcap_loop() processes packets from a live capture or ``savefile'' until cnt packets are processed, the end of the ``savefile'' is reached
when reading from a ``savefile'', pcap_breakloop() is called, or an error occurs. It does not return when live read timeouts occur. A
value of -1 or 0 for cnt is equivalent to infinity, so that packets are processed until another ending condition occurs.
pcap_dispatch() processes packets from a live capture or ``savefile'' until cnt packets are processed, the end of the current bufferful of
packets is reached when doing a live capture, the end of the ``savefile'' is reached when reading from a ``savefile'', pcap_breakloop() is
called, or an error occurs. Thus, when doing a live capture, cnt is the maximum number of packets to process before returning, but is not
a minimum number; when reading a live capture, only one bufferful of packets is read at a time, so fewer than cnt packets may be processed.
A value of -1 or 0 for cnt causes all the packets received in one buffer to be processed when reading a live capture, and causes all the
packets in the file to be processed when reading a ``savefile''.
(In older versions of libpcap, the behavior when cnt was 0 was undefined; different platforms and devices behaved differently, so code that
must work with older versions of libpcap should use -1, nor 0, as the value of cnt.)
callback specifies a pcap_handler routine to be called with three arguments: a u_char pointer which is passed in the user argument to
pcap_loop() or pcap_dispatch(), a const struct pcap_pkthdr pointer pointing to the packet time stamp and lengths, and a const u_char
pointer to the first caplen (as given in the struct pcap_pkthdr a pointer to which is passed to the callback routine) bytes of data from
the packet. The struct pcap_pkthdr and the packet data are not to be freed by the callback routine, and are not guaranteed to be valid
after the callback routine returns; if the code needs them to be valid after the callback, it must make a copy of them.
RETURN VALUE
pcap_loop() returns 0 if cnt is exhausted, -1 if an error occurs, or -2 if the loop terminated due to a call to pcap_breakloop() before any
packets were processed. It does not return when live read timeouts occur; instead, it attempts to read more packets.
pcap_dispatch() returns the number of packets processed on success; this can be 0 if no packets were read from a live capture (if, for
example, they were discarded because they didn't pass the packet filter, or if, on platforms that support a read timeout that starts before
any packets arrive, the timeout expires before any packets arrive, or if the file descriptor for the capture device is in non-blocking mode
and no packets were available to be read) or if no more packets are available in a ``savefile.'' It returns -1 if an error occurs or -2 if
the loop terminated due to a call to pcap_breakloop() before any packets were processed. If your application uses pcap_breakloop(), make
sure that you explicitly check for -1 and -2, rather than just checking for a return value < 0.
If -1 is returned, pcap_geterr() or pcap_perror() may be called with p as an argument to fetch or display the error text.
SEE ALSO pcap(3PCAP), pcap_geterr(3PCAP), pcap_breakloop(3PCAP)
24 December 2008 PCAP_LOOP(3PCAP)