.TH TORRENT 1
.SH NAME
torrent \- bittorrent client
.SH SYNOPSIS
.B ip/torrent
[
.B -d
] [
.B -v
] [
.B -p
] [
.B -m
.I mtpt
] [
.B -t
.I tracker-url
] [
.B -w
.I webseed-url
] [
.B -s
] [
.B -c
] [
.B -i
.I peer-id
] [
.B -A
.I user-agent
] [
.I file
]
.SH DESCRIPTION
BitTorrent is a protocol for efficient file distribution
over the internet. Files are split into small pieces
that are then downloaded by clients in random order.
As soon as a client completes a piece, it makes the piece 
available for others to download.
.PP
To find other clients (peers), a tracker-server is
contacted.
.PP
Before files can be transmitted, a torrent-file needs
to be created describing the pieces of the files and
other meta-data like network addresses of the trackers.
.PP
This is done with the
.B -c
option. If provided,
.I torrent
reads the file given at the final
.I file
argument (or standard-input when omitted) and writes
a torrent file to standard-output and exits.
A
.I tracker-url
should be given with the
.B -t
option in that case. A list of trackers can be obtained
on the web, see the examples below.
.PP
If the files in the torrent are also available from a url, a
.I webseed-url
can be passed with the
.B -w
option. If
.I webseed-url
ends with a slash, the filename, from the torrent, concatenated
with the url forms the target url.
.PP
Without the
.B -c
option,
.I torrent
downloads the files that are described in the torrent-file
given by the
.I file
argument to the current working directory. If no
.I file
is given, the torrent is read from standard-input.
.PP
Normally, the program exits immediately after all pieces
have been completed.
The
.B -s
option causes it to keep running and serve the remaining
clients (also known as seeding).
.PP
Trackers use a subset of the HTTP protocol, so an
alternative 
.IR webfs (4)
mountpoint can be given with the
.B -m
option (defaults to
.BR /mnt/web ).
.PP
The
.B -v
option causes
.I torrent
to list the files in the torrent-file before downloading.
.PP
The
.B -d
option produces verbose debug output to standard-error.
.PP
To monitor the download progress, the
.B -p
option can be given to cause the completed and total number of
pieces written as a line of text to standard-output in one
second intervals.
.PP
The
.B -i
option allows you to set the 20-byte
.I peer-id
that is sent to trackers and peers. If less than 20 bytes, the
.I peer-id
will be padded on the right with random ASCII numbers. The
.B -A
option allows setting the http 
.I user-agent
string that is used to contact the tracker. These options are
useful to fool trackers that filter clients based on the
.I peer-id
or
.I user-agent
.
.SH EXAMPLES
Create new torrent file
.EX
ip/torrent -t http://exodus.desync.com/announce \\
	-c 9atom.iso >9atom.torrent
.EE
.LP
Download the latest iso file of the distribution 
.EX
cd /tmp
hget http://r-36.net/9front/9front.iso.bz2.torrent | \\
	ip/torrent -pv | \\
	aux/statusbar 'download...'
.EE
.LP
Get list of public alive trackers to choose from
.EX
hget http://www.trackon.org/api/live
.EE
.LP
.SH SOURCE
.B /sys/src/cmd/ip/torrent.c
.SH "SEE ALSO"
.IR hget (1),
.IR webfs (4)
.SH HISTORY
.I Torrent
first appeared in 9front (October, 2011).