Updated: 2021/Apr/14

PCAP_DUMP_OPEN(3)          Library Functions Manual          PCAP_DUMP_OPEN(3)

       pcap_dump_open, pcap_dump_fopen - open a file to which to write packets

       #include <pcap/pcap.h>

       pcap_dumper_t *pcap_dump_open(pcap_t *p, const char *fname);
       pcap_dumper_t *pcap_dump_open_append(pcap_t *p, const char *fname);
       pcap_dumper_t *pcap_dump_fopen(pcap_t *p, FILE *fp);

       pcap_dump_open() is called to open a ``savefile'' for writing.  fname
       specifies the name of the file to open. The file will have the same
       format as those used by tcpdump(8) and tcpslice(1).  The name "-" is a
       synonym for stdout.

       pcap_dump_fopen() is called to write data to an existing open stream
       fp; this stream will be closed by a subsequent call to
       pcap_dump_close(3).  Note that on Windows, that stream should be opened
       in binary mode.

       p is a capture or ``savefile'' handle returned by an earlier call to
       pcap_create(3) and activated by an earlier call to pcap_activate(3), or
       returned by an earlier call to pcap_open_offline(3), pcap_open_live(3),
       or pcap_open_dead(3).  The time stamp precision, link-layer type, and
       snapshot length from p are used as the link-layer type and snapshot
       length of the output file.

       pcap_dump_open_append() is like pcap_dump_open() but does not create
       the file if it does not exist and, if it does already exist, and is a
       pcap file with the same byte order as the host opening the file, and
       has the same time stamp precision, link-layer header type, and snapshot
       length as p, it will write new packets at the end of the file.

       A pointer to a pcap_dumper_t structure to use in subsequent
       pcap_dump(3) and pcap_dump_close(3) calls is returned on success.  NULL
       is returned on failure.  If NULL is returned, pcap_geterr(3) can be
       used to get the error text.

       The pcap_dump_open_append() function became available in libpcap
       release 1.7.2.  In previous releases, there is no support for appending
       packets to an existing savefile.

       pcap(3), pcap-savefile(5)

                                22 August 2018               PCAP_DUMP_OPEN(3)