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<img alt="Erlang logo" src="../../../../doc/erlang-logo.png"><br><small><a href="index.html">Reference Manual</a><br><a href="release_notes.html">Release Notes</a><br><a href="../pdf/ssh-2.1.2.pdf">PDF</a><br><a href="../../../../doc/index.html">Top</a></small><p><strong>SSH</strong><br><strong>Reference Manual</strong><br><small>Version 2.1.2</small></p>
<br><a href="javascript:openAllFlips()">Expand All</a><br><a href="javascript:closeAllFlips()">Contract All</a><p><small><strong>Table of Contents</strong></small></p>
<ul class="flipMenu">
<li id="no" title="ssh " expanded="false">ssh<ul>
<li><a href="ssh.html">
Top of manual page
</a></li>
<li title="close-1"><a href="ssh.html#close-1">close/1</a></li>
<li title="connect-3"><a href="ssh.html#connect-3">connect/3</a></li>
<li title="connect-4"><a href="ssh.html#connect-4">connect/4</a></li>
<li title="connection_info-2"><a href="ssh.html#connection_info-2">connection_info/2</a></li>
<li title="daemon-1"><a href="ssh.html#daemon-1">daemon/1</a></li>
<li title="daemon-2"><a href="ssh.html#daemon-2">daemon/2</a></li>
<li title="daemon-3"><a href="ssh.html#daemon-3">daemon/3</a></li>
<li title="shell-1"><a href="ssh.html#shell-1">shell/1</a></li>
<li title="shell-2"><a href="ssh.html#shell-2">shell/2</a></li>
<li title="shell-3"><a href="ssh.html#shell-3">shell/3</a></li>
<li title="start-0"><a href="ssh.html#start-0">start/0</a></li>
<li title="start-1"><a href="ssh.html#start-1">start/1</a></li>
<li title="stop-0"><a href="ssh.html#stop-0">stop/0</a></li>
<li title="stop_daemon-1"><a href="ssh.html#stop_daemon-1">stop_daemon/1</a></li>
<li title="stop_daemon-2"><a href="ssh.html#stop_daemon-2">stop_daemon/2</a></li>
<li title="stop_listener-1"><a href="ssh.html#stop_listener-1">stop_listener/1</a></li>
<li title="stop_listener-2"><a href="ssh.html#stop_listener-2">stop_listener/2</a></li>
</ul>
</li>
<li id="loadscrollpos" title="ssh_channel " expanded="true">ssh_channel<ul>
<li><a href="ssh_channel.html">
Top of manual page
</a></li>
<li title="call-2"><a href="ssh_channel.html#call-2">call/2</a></li>
<li title="call-3"><a href="ssh_channel.html#call-3">call/3</a></li>
<li title="cast-2"><a href="ssh_channel.html#cast-2">cast/2</a></li>
<li title="enter_loop-1"><a href="ssh_channel.html#enter_loop-1">enter_loop/1</a></li>
<li title="init-1"><a href="ssh_channel.html#init-1">init/1</a></li>
<li title="reply-2"><a href="ssh_channel.html#reply-2">reply/2</a></li>
<li title="start-4"><a href="ssh_channel.html#start-4">start/4</a></li>
<li title="start_link-4"><a href="ssh_channel.html#start_link-4">start_link/4</a></li>
<li title="CallbackModule:code_change-3"><a href="ssh_channel.html#CallbackModule:code_change-3">CallbackModule:code_change/3</a></li>
<li title="CallbackModule:init-1"><a href="ssh_channel.html#CallbackModule:init-1">CallbackModule:init/1</a></li>
<li title="CallbackModule:handle_call-3"><a href="ssh_channel.html#CallbackModule:handle_call-3">CallbackModule:handle_call/3</a></li>
<li title="CallbackModule:handle_cast-2"><a href="ssh_channel.html#CallbackModule:handle_cast-2">CallbackModule:handle_cast/2</a></li>
<li title="CallbackModule:handle_msg-2"><a href="ssh_channel.html#CallbackModule:handle_msg-2">CallbackModule:handle_msg/2</a></li>
<li title="CallbackModule:handle_ssh_msg-2"><a href="ssh_channel.html#CallbackModule:handle_ssh_msg-2">CallbackModule:handle_ssh_msg/2</a></li>
<li title="CallbackModule:terminate-2"><a href="ssh_channel.html#CallbackModule:terminate-2">CallbackModule:terminate/2</a></li>
</ul>
</li>
<li id="no" title="ssh_connection " expanded="false">ssh_connection<ul>
<li><a href="ssh_connection.html">
Top of manual page
</a></li>
<li title="adjust_window-3"><a href="ssh_connection.html#adjust_window-3">adjust_window/3</a></li>
<li title="close-2"><a href="ssh_connection.html#close-2">close/2</a></li>
<li title="exec-4"><a href="ssh_connection.html#exec-4">exec/4</a></li>
<li title="exit_status-3"><a href="ssh_connection.html#exit_status-3">exit_status/3</a></li>
<li title="reply_request-4"><a href="ssh_connection.html#reply_request-4">reply_request/4</a></li>
<li title="send-3"><a href="ssh_connection.html#send-3">send/3</a></li>
<li title="send-4"><a href="ssh_connection.html#send-4">send/4</a></li>
<li title="send-4"><a href="ssh_connection.html#send-4">send/4</a></li>
<li title="send-5"><a href="ssh_connection.html#send-5">send/5</a></li>
<li title="send_eof-2"><a href="ssh_connection.html#send_eof-2">send_eof/2</a></li>
<li title="session_channel-2"><a href="ssh_connection.html#session_channel-2">session_channel/2</a></li>
<li title="session_channel-4"><a href="ssh_connection.html#session_channel-4">session_channel/4</a></li>
<li title="setenv-5"><a href="ssh_connection.html#setenv-5">setenv/5</a></li>
<li title="shell-2"><a href="ssh_connection.html#shell-2">shell/2</a></li>
<li title="subsystem-4"><a href="ssh_connection.html#subsystem-4">subsystem/4</a></li>
</ul>
</li>
<li id="no" title="ssh_sftp " expanded="false">ssh_sftp<ul>
<li><a href="ssh_sftp.html">
Top of manual page
</a></li>
<li title="start_channel-1"><a href="ssh_sftp.html#start_channel-1">start_channel/1</a></li>
<li title="start_channel-2"><a href="ssh_sftp.html#start_channel-2">start_channel/2</a></li>
<li title="start_channel-2"><a href="ssh_sftp.html#start_channel-2">start_channel/2</a></li>
<li title="start_channel-3"><a href="ssh_sftp.html#start_channel-3">start_channel/3</a></li>
<li title="stop_channel-1"><a href="ssh_sftp.html#stop_channel-1">stop_channel/1</a></li>
<li title="read_file-2"><a href="ssh_sftp.html#read_file-2">read_file/2</a></li>
<li title="read_file-3"><a href="ssh_sftp.html#read_file-3">read_file/3</a></li>
<li title="write_file-3"><a href="ssh_sftp.html#write_file-3">write_file/3</a></li>
<li title="write_file-4"><a href="ssh_sftp.html#write_file-4">write_file/4</a></li>
<li title="list_dir-2"><a href="ssh_sftp.html#list_dir-2">list_dir/2</a></li>
<li title="list_dir-3"><a href="ssh_sftp.html#list_dir-3">list_dir/3</a></li>
<li title="open-3"><a href="ssh_sftp.html#open-3">open/3</a></li>
<li title="open-4"><a href="ssh_sftp.html#open-4">open/4</a></li>
<li title="opendir-2"><a href="ssh_sftp.html#opendir-2">opendir/2</a></li>
<li title="opendir-3"><a href="ssh_sftp.html#opendir-3">opendir/3</a></li>
<li title="close-2"><a href="ssh_sftp.html#close-2">close/2</a></li>
<li title="close-3"><a href="ssh_sftp.html#close-3">close/3</a></li>
<li title="read-3"><a href="ssh_sftp.html#read-3">read/3</a></li>
<li title="read-4"><a href="ssh_sftp.html#read-4">read/4</a></li>
<li title="pread-4"><a href="ssh_sftp.html#pread-4">pread/4</a></li>
<li title="pread-5"><a href="ssh_sftp.html#pread-5">pread/5</a></li>
<li title="aread-3"><a href="ssh_sftp.html#aread-3">aread/3</a></li>
<li title="apread-4"><a href="ssh_sftp.html#apread-4">apread/4</a></li>
<li title="write-3"><a href="ssh_sftp.html#write-3">write/3</a></li>
<li title="write-4"><a href="ssh_sftp.html#write-4">write/4</a></li>
<li title="pwrite-4"><a href="ssh_sftp.html#pwrite-4">pwrite/4</a></li>
<li title="pwrite-5"><a href="ssh_sftp.html#pwrite-5">pwrite/5</a></li>
<li title="awrite-3"><a href="ssh_sftp.html#awrite-3">awrite/3</a></li>
<li title="apwrite-4"><a href="ssh_sftp.html#apwrite-4">apwrite/4</a></li>
<li title="position-3"><a href="ssh_sftp.html#position-3">position/3</a></li>
<li title="position-4"><a href="ssh_sftp.html#position-4">position/4</a></li>
<li title="read_file_info-2"><a href="ssh_sftp.html#read_file_info-2">read_file_info/2</a></li>
<li title="read_file_info-3"><a href="ssh_sftp.html#read_file_info-3">read_file_info/3</a></li>
<li title="read_link_info-2"><a href="ssh_sftp.html#read_link_info-2">read_link_info/2</a></li>
<li title="read_link_info-3"><a href="ssh_sftp.html#read_link_info-3">read_link_info/3</a></li>
<li title="write_file_info-3"><a href="ssh_sftp.html#write_file_info-3">write_file_info/3</a></li>
<li title="write_file_info-4"><a href="ssh_sftp.html#write_file_info-4">write_file_info/4</a></li>
<li title="read_link-2"><a href="ssh_sftp.html#read_link-2">read_link/2</a></li>
<li title="read_link-3"><a href="ssh_sftp.html#read_link-3">read_link/3</a></li>
<li title="make_symlink-3"><a href="ssh_sftp.html#make_symlink-3">make_symlink/3</a></li>
<li title="make_symlink-4"><a href="ssh_sftp.html#make_symlink-4">make_symlink/4</a></li>
<li title="rename-3"><a href="ssh_sftp.html#rename-3">rename/3</a></li>
<li title="rename-4"><a href="ssh_sftp.html#rename-4">rename/4</a></li>
<li title="delete-2"><a href="ssh_sftp.html#delete-2">delete/2</a></li>
<li title="delete-3"><a href="ssh_sftp.html#delete-3">delete/3</a></li>
<li title="make_dir-2"><a href="ssh_sftp.html#make_dir-2">make_dir/2</a></li>
<li title="make_dir-3"><a href="ssh_sftp.html#make_dir-3">make_dir/3</a></li>
<li title="del_dir-2"><a href="ssh_sftp.html#del_dir-2">del_dir/2</a></li>
<li title="del_dir-3"><a href="ssh_sftp.html#del_dir-3">del_dir/3</a></li>
</ul>
</li>
<li id="no" title="ssh_sftpd " expanded="false">ssh_sftpd<ul>
<li><a href="ssh_sftpd.html">
Top of manual page
</a></li>
<li title="subsystem_spec-1"><a href="ssh_sftpd.html#subsystem_spec-1">subsystem_spec/1</a></li>
</ul>
</li>
</ul>
</div></div>
<div id="content">
<div class="innertube">
<!-- refpage --><center><h1>ssh_channel</h1></center>
<h3>MODULE</h3>
<div class="REFBODY">ssh_channel</div>
<h3>MODULE SUMMARY</h3>
<div class="REFBODY">Generic Ssh Channel Behavior
</div>
<h3>DESCRIPTION</h3>
<div class="REFBODY"><p>
<p>Ssh services are implemented as channels that are multiplexed
over an ssh connection and communicates via the ssh connection
protocol. This module provides a callback API that takes care of
generic channel aspects such as flow control and close messages
and lets the callback functions take care of the service specific
parts.
</p>
</p></div>
<h3><a name="id63984">COMMON DATA TYPES </a></h3>
<div class="REFBODY">
<p>Type definitions that are used more than once in this module
and/or abstractions to indicate the intended use of the data
type:</p>
<p><span class="code">boolean() = true | false </span></p>
<p><span class="code">string() = list of ASCII characters</span></p>
<p><span class="code">timeout() = infinity | integer() - in milliseconds.</span></p>
<p><span class="code">ssh_connection_ref() - opaque to the user returned by
ssh:connect/3 or sent to a ssh channel process</span></p>
<p><span class="code">ssh_channel_id() = integer() </span></p>
<p><span class="code">ssh_data_type_code() = 1 ("stderr") | 0 ("normal") are
currently valid values see RFC 4254 section 5.2.</span></p>
</div>
<h3>EXPORTS</h3>
<p><a name="call-2"><span class="bold_code">call(ChannelRef, Msg) -></span></a><br><a name="call-3"><span class="bold_code">call(ChannelRef, Msg, Timeout) -> Reply | {error, Reason}</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">ChannelRef = pid() </span><br>
</div>
<div class="REFBODY">As returned by start_link/4 </div>
<div class="REFTYPES">
<span class="bold_code">Msg = term() </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Timeout = timeout() </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Reply = term() </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Reason = closed | timeout </span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>Makes a synchronous call to the channel process by sending
a message and waiting until a reply arrives or a timeout
occurs. The channel will call
<span class="code">CallbackModule:handle_call/3</span> to handle the message.
If the channel process does not exist <span class="code">{error, closed}</span> is returned.
</p>
</p></div>
<p><a name="cast-2"><span class="bold_code">cast(ChannelRef, Msg) -> ok </span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">ChannelRef = pid() </span><br>
</div>
<div class="REFBODY">As returned by start_link/4 </div>
<div class="REFTYPES">
<span class="bold_code">Msg = term() </span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>Sends an asynchronous message to the channel process and
returns ok immediately, ignoring if the destination node or
channel process does not exist. The channel will call
<span class="code">CallbackModule:handle_cast/2</span> to handle the message.
</p>
</p></div>
<p><a name="enter_loop-1"><span class="bold_code">enter_loop(State) -> _ </span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code"> State = term() - as returned by ssh_channel:init/1</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p> Makes an existing process into a <span class="code">ssh_channel</span>
process. Does not return, instead the calling process will
enter the <span class="code">ssh_channel</span> process receive loop and become a
<span class="code">ssh_channel process.</span> The process must have been started using
one of the start functions in proc_lib, see <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','stdlib','proc_lib.html');">proc_lib(3)</a></span>. The
user is responsible for any initialization of the process
and needs to call ssh_channel:init/1.
</p>
</p></div>
<p><a name="init-1"><span class="bold_code">init(Options) -> {ok, State} | {ok, State, Timeout} | {stop, Reason} </span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code"> Options = [{Option, Value}]</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>
The following options must be present:
</p>
<dl>
<dt><strong><span class="code">{channel_cb, atom()}</span></strong></dt>
<dd>The module that implements the channel behavior.</dd>
<dt><strong><span class="code">{init_args(), list()}</span></strong></dt>
<dd> The list of arguments to the callback modules
init function.</dd>
<dt><strong><span class="code">{cm, connection_ref()}</span></strong></dt>
<dd> Reference to the ssh connection.</dd>
<dt><strong><span class="code">{channel_id, channel_id()}</span></strong></dt>
<dd> Id of the ssh channel.</dd>
</dl>
<div class="note">
<div class="label">Note</div>
<div class="content"><p><p>This function is normally not called by the user, it is
only needed if for some reason the channel process needs
to be started with help of <span class="code">proc_lib</span> instead calling
<span class="code">ssh_channel:start/4</span> or <span class="code">ssh_channel:start_link/4</span> </p>
</p></div>
</div>
</p></div>
<p><a name="reply-2"><span class="bold_code">reply(Client, Reply) -> _</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">Client - opaque to the user, see explanation below</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Reply = term()</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>This function can be used by a channel to explicitly send a
reply to a client that called <span class="code">call/[2,3]</span> when the reply
cannot be defined in the return value of
<span class="code">CallbackModule:handle_call/3</span>.</p>
<p><span class="code">Client</span> must be the <span class="code">From</span> argument provided to
the callback function <span class="code">handle_call/3</span>.
<span class="code">Reply</span> is an arbitrary term,
which will be given back to the client as the return value of
<span class="code">ssh_channel:call/[2,3].</span></p>
</p></div>
<p><a name="start-4"><span class="bold_code">start(SshConnection, ChannelId, ChannelCb, CbInitArgs) -> </span></a><br><a name="start_link-4"><span class="bold_code">start_link(SshConnection, ChannelId, ChannelCb, CbInitArgs) ->
{ok, ChannelRef} | {error, Reason}</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">SshConnection = ssh_connection_ref()</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">ChannelId = ssh_channel_id() </span><br>
</div>
<div class="REFBODY"> As returned by ssh_connection:session_channel/[2,4]</div>
<div class="REFTYPES">
<span class="bold_code">ChannelCb = atom()</span><br>
</div>
<div class="REFBODY"> The name of the module implementing the service specific parts
of the channel.</div>
<div class="REFTYPES">
<span class="bold_code">CbInitArgs = [term()]</span><br>
</div>
<div class="REFBODY">Argument list for the init function in the callback module. </div>
<div class="REFTYPES">
<span class="bold_code">ChannelRef = pid()</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>Starts a processes that handles a ssh channel. Will be
called internally by the ssh daemon or explicitly by the ssh
client implementations. A channel process traps exit signals
by default.
</p>
</p></div>
<h3><a name="id64374">CALLBACK FUNCTIONS</a></h3>
<div class="REFBODY">
<p>The functions init/1, terminate/2, handle_ssh_msg/2 and
handle_msg/2 are the functions that are required to provide the
implementation for a server side channel, such as a ssh subsystem
channel that can be plugged into the erlang ssh daemon see
<span class="bold_code"><a href="ssh.html">ssh:daemon/[2, 3]</a></span>. The
handle_call/3, handle_cast/2 code_change/3 and enter_loop/1
functions are only relevant when implementing a client side
channel.</p>
</div>
<h3><a name="id64399"> CALLBACK TIMEOUTS</a></h3>
<div class="REFBODY">
<a name="cb_timeouts"></a>
<p> If an integer timeout value is provided in a return value of
one of the callback functions, a timeout will occur unless a
message is received within <span class="code">Timeout</span> milliseconds. A timeout
is represented by the atom <span class="code">timeout</span> which should be handled
by the <span class="bold_code"><a href="#handle_msg">handle_msg/2</a></span>
callback function. The atom infinity can be used to wait
indefinitely, this is the default value. </p>
</div>
<h3>EXPORTS</h3>
<p><a name="CallbackModule:code_change-3"><span class="bold_code">CallbackModule:code_change(OldVsn, State, Extra) -> {ok,
NewState}</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code"> Converts process state when code is changed.</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>This function is called by a client side channel when it
should update its internal state during a release
upgrade/downgrade, i.e. when the instruction
<span class="code">{update,Module,Change,...}</span> where
<span class="code">Change={advanced,Extra}</span> is given in the <span class="code">appup</span>
file. See <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','doc/design_principles','release_handling.html#instr');">OTP
Design Principles</a></span> for more information. Any new
connection will benefit from a server side upgrade but
already started connections on the server side will not be
affected.
</p>
<div class="note">
<div class="label">Note</div>
<div class="content"><p><p>If there are long lived ssh connections and more
than one upgrade in a short time this may cause the old
connections to fail as only two versions of the code may
be loaded simultaneously.</p></p></div>
</div>
<p>In the case of an upgrade, <span class="code">OldVsn</span> is <span class="code">Vsn</span>, and
in the case of a downgrade, <span class="code">OldVsn</span> is
<span class="code">{down,Vsn}</span>. <span class="code">Vsn</span> is defined by the <span class="code">vsn</span>
attribute(s) of the old version of the callback module
<span class="code">Module</span>. If no such attribute is defined, the version
is the checksum of the BEAM file.</p>
<p><span class="code">State</span> is the internal state of the channel.</p>
<p><span class="code">Extra</span> is passed as-is from the <span class="code">{advanced,Extra}</span>
part of the update instruction.</p>
<p>The function should return the updated internal state.</p>
</p></div>
<p><a name="CallbackModule:init-1"><span class="bold_code">CallbackModule:init(Args) -> {ok, State} | {ok, State, Timeout} |
{stop, Reason}</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code"> Args = term() </span><br>
</div>
<div class="REFBODY"> Last argument to ssh_channel:start_link/4.</div>
<div class="REFTYPES">
<span class="bold_code"> State = term() </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Timeout = timeout() </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code"> Reason = term() </span><br>
</div>
</div>
<div class="REFBODY"><p>
<p> Makes necessary initializations and returns the initial channel
state if the initializations succeed.
</p>
<p>For more detailed information on timeouts see the section
<span class="bold_code"><a href="#cb_timeouts">CALLBACK TIMEOUTS</a></span>. </p>
</p></div>
<p><a name="CallbackModule:handle_call-3"><span class="bold_code">CallbackModule:handle_call(Msg, From, State) -> Result</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">Msg = term()</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">From = opaque to the user should be used as argument to
ssh_channel:reply/2</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">State = term()</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Result = {reply, Reply, NewState} | {reply, Reply, NewState, Timeout}
| {noreply, NewState} | {noreply , NewState, Timeout}
| {stop, Reason, Reply, NewState} | {stop, Reason, NewState} </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Reply = term() - will be the return value of ssh_channel:call/[2,3]</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Timeout = timeout() </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">NewState = term() - a possible updated version of State</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Reason = term()</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>Handles messages sent by calling
<span class="code">ssh_channel:call/[2,3]</span>
</p>
<p>For more detailed information on timeouts see the section
<span class="bold_code"><a href="#cb_timeouts">CALLBACK TIMEOUTS</a></span>. </p>
</p></div>
<p><a name="CallbackModule:handle_cast-2"><span class="bold_code">CallbackModule:handle_cast(Msg, State) -> Result</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">Msg = term()</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">State = term()</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Result = {noreply, NewState} | {noreply, NewState, Timeout}
| {stop, Reason, NewState}</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">NewState = term() - a possible updated version of State</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Timeout = timeout() </span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">Reason = term()</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p> Handles messages sent by calling
<span class="code">ssh_channel:cast/2</span>
</p>
<p>For more detailed information on timeouts see the section
<span class="bold_code"><a href="#cb_timeouts">CALLBACK TIMEOUTS</a></span>. </p>
<a name="handle_msg"></a>
</p></div>
<p><a name="CallbackModule:handle_msg-2"><span class="bold_code">CallbackModule:handle_msg(Msg, State) -> {ok, State} |
{stop, ChannelId, State}</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">Msg = timeout | term()</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">State = term() </span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>Handle other messages than ssh connection protocol, call or
cast messages sent to the channel.
</p>
<p> Possible erlang 'EXIT'-messages should be handled by this
function and all channels should handle the following message.</p>
<dl>
<dt><strong><span class="code">{ssh_channel_up, ssh_channel_id(),
ssh_connection_ref()}</span></strong></dt>
<dd>This is the first messages that will be received
by the channel, it is sent just before
the ssh_channel:init/1 function returns successfully.
This is especially useful if the server wants
to send a message to the client without first receiving
a message from the client. If the message is not useful
for your particular problem just ignore it by immediately
returning {ok, State}.
</dd>
</dl>
</p></div>
<p><a name="CallbackModule:handle_ssh_msg-2"><span class="bold_code">CallbackModule:handle_ssh_msg(Msg, State) -> {ok, State} | {stop,
ssh_channel_id(), State}</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">Msg = {ssh_cm, ssh_connection_ref(), SshMsg}</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code"> SshMsg = tuple() - see message list below</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">State = term()</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p> Handles ssh connection protocol messages that may need
service specific attention.
</p>
<p> All channels should handle the following messages. For
channels implementing subsystems the handle_ssh_msg-callback
will not be called for any other messages. </p>
<dl>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(), {data, ssh_channel_id(),
ssh_data_type_code(), binary() = Data}}</span></strong></dt>
<dd> Data has arrived on the channel. When the callback
for this message returns the channel behavior will adjust
the ssh flow control window.</dd>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(), {eof,
ssh_channel_id()}}</span></strong></dt>
<dd>Indicteas that the other side will not send any more
data.</dd>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(), {signal,
ssh_channel_id(), ssh_signal()}} </span></strong></dt>
<dd>A signal can be delivered to the remote
process/service using the following message. Some systems
may not implement signals, in which case they should ignore
this message.</dd>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(),
{exit_signal, ssh_channel_id(), string() = exit_signal,
string() = ErrorMsg, string() =
LanguageString}}</span></strong></dt>
<dd>A remote execution may terminate violently due to a
signal then this message may be received. For details on valid string
values see RFC 4254 section 6.10</dd>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(), {exit_status,
ssh_channel_id(), integer() = ExitStatus}}</span></strong></dt>
<dd> When the command running at the other end terminates,
the following message can be sent to return the exit status
of the command. A zero 'exit_status' usually means that the
command terminated successfully.</dd>
</dl>
<p> Channels implementing a shell and command execution on the server side
should also handle the following messages. </p>
<dl>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(), {env, ssh_channel_id(),
boolean() = WantReply, string() = Var, string() = Value}}</span></strong></dt>
<dd> Environment variables may be passed to the
shell/command to be started later. Note that before the
callback returns it should call the function
ssh_connection:reply_request/4 with the boolean value of <span class="code">
WantReply</span> as the second argument.
</dd>
<dt><strong><span class="code">{ssh_cm, ConnectionRef, {exec, ssh_channel_id(),
boolean() = WantReply, string() = Cmd}}</span></strong></dt>
<dd> This message will request that the server start the
execution of the given command. Note that before the
callback returns it should call the function
ssh_connection:reply_request/4 with the boolean value of <span class="code">
WantReply</span> as the second argument.</dd>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(), {pty, ssh_channel_id(),
boolean() = WantReply, {string() = Terminal, integer() = CharWidth,
integer() = RowHeight, integer() = PixelWidth, integer() = PixelHight,
[{atom() | integer() = Opcode,
integer() = Value}] = TerminalModes}}}</span></strong></dt>
<dd>A pseudo-terminal has been requested for the
session. Terminal is the value of the TERM environment
variable value (e.g., vt100). Zero dimension parameters must
be ignored. The character/row dimensions override the pixel
dimensions (when nonzero). Pixel dimensions refer to the
drawable area of the window. The <span class="code">Opcode</span> in the
<span class="code">TerminalModes</span> list is the mnemonic name, represented
as an lowercase erlang atom, defined in RFC 4254 section 8,
or the opcode if the mnemonic name is not listed in the
RFC. Example <span class="code">OP code: 53, mnemonic name ECHO erlang atom:
echo</span>. Note that before the callback returns it should
call the function ssh_connection:reply_request/4 with the
boolean value of <span class="code"> WantReply</span> as the second
argument.</dd>
<dt><strong><span class="code">{ssh_cm, ConnectionRef, {shell, boolean() =
WantReply}}</span></strong></dt>
<dd> This message will request that the user's default
shell be started at the other end. Note that before the
callback returns it should call the function
ssh_connection:reply_request/4 with the value of <span class="code">
WantReply</span> as the second argument.
</dd>
<dt><strong><span class="code"> {ssh_cm, ssh_connection_ref(), {window_change,
ssh_channel_id(), integer() = CharWidth, integer() = RowHeight,
integer() = PixWidth, integer() = PixHeight}}</span></strong></dt>
<dd> When the window (terminal) size changes on the client
side, it MAY send a message to the other side to inform it
of the new dimensions.</dd>
</dl>
<p> The following message is completely taken care of by the
ssh channel behavior</p>
<dl>
<dt><strong><span class="code">{ssh_cm, ssh_connection_ref(), {closed,
ssh_channel_id()}}</span></strong></dt>
<dd> The channel behavior will send a close message to the
other side if such a message has not already been sent and
then terminate the channel with reason normal.</dd>
</dl>
</p></div>
<p><a name="CallbackModule:terminate-2"><span class="bold_code">CallbackModule:terminate(Reason, State) -> _</span></a><br></p>
<div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES">
<span class="bold_code">Reason = term()</span><br>
</div>
<div class="REFTYPES">
<span class="bold_code">State = term()</span><br>
</div>
</div>
<div class="REFBODY"><p>
<p>This function is called by a channel process when it is
about to terminate. Before this function is called ssh_connection:close/2
will be called if it has not been called earlier.
This function should be the opposite of <span class="code">CallbackModule:init/1</span>
and do any necessary cleaning up. When it returns, the
channel process terminates with reason <span class="code">Reason</span>. The return value is
ignored.
</p>
</p></div>
</div>
<div class="footer">
<hr>
<p>Copyright © 2005-2012 Ericsson AB. All Rights Reserved.</p>
</div>
</div>
</div></body>
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