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.TH PCAP_DUMP_OPEN 3PCAP "22 June 2018"
.SH NAME
pcap_dump_open, pcap_dump_fopen \- open a file to which to write packets
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.nf
.LP
.ft B
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);
.ft
.fi
.SH DESCRIPTION
.B pcap_dump_open()
is called to open a ``savefile'' for writing.
.I fname
specifies the name of the file to open. The file will have
the same format as those used by
.BR tcpdump (1)
and
.BR tcpslice (1).
The name "-" is a synonym
for
.BR stdout .
.PP
.B pcap_dump_fopen()
is called to write data to an existing open stream
.IR fp ;
this stream will be closed by a subsequent call to
.BR pcap_dump_close() .
Note that on Windows, that stream should be opened in binary mode.
.PP
.I p
is a capture or ``savefile'' handle returned by an earlier call to
.B pcap_create()
and activated by an earlier call to
.BR pcap_activate() ,
or returned by an earlier call to
.BR pcap_open_offline() ,
.BR pcap_open_live() ,
or
.BR pcap_open_dead() .
The time stamp precision, link-layer type, and snapshot length from
.I p
are used as the link-layer type and snapshot length of the output file.
.PP
.B pcap_dump_open_append()
is like
.B 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
.IR p ,
it will write new packets at the end of the file.
.SH RETURN VALUES
A pointer to a
.B pcap_dumper_t
structure to use in subsequent
.B pcap_dump()
and
.B pcap_dump_close()
calls is returned on success.
.B NULL
is returned on failure.
If
.B NULL
is returned,
.B pcap_geterr(\fIp\fB)
can be used to get the error text.
.SH SEE ALSO
pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP),
\%pcap_open_offline(3PCAP), pcap_open_live(3PCAP), pcap_open_dead(3PCAP),
pcap_dump(3PCAP), pcap_dump_close(3PCAP), pcap_geterr(3PCAP),
\%pcap-savefile(5)