Class SshExpect

Namespace

SshSharp

Assembly

SshSharp.dll

Drives an interactive program, as expect does: wait until its output shows a prompt or other text, then send the next input. Wrap a shell session (StartShellAsync(SshSessionOptions?, CancellationToken), usually with a terminal) and use ExpectAsync(string, CancellationToken), ReadLineAsync(CancellationToken) and SendLineAsync(string, CancellationToken); timeouts are CancellationTokens.

public sealed class SshExpect

Inheritance

object

SshExpect

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

This reads the output stream itself: do not read it elsewhere while using this. Output is decoded with Encoding, and a character split across two reads is decoded whole; invalid bytes become U+FFFD and are never dropped silently. Text after a match stays buffered for the next call. Without a terminal, standard error is a separate stream and is not searched.

A regular expression is tried against the output received so far, so a pattern that could also match a shorter prefix (\d+ against a number still arriving) may match early; anchor patterns to what follows them, such as a prompt's trailing $ .

Plain text is searched for only in the output that arrived since the last search (and the few characters before it), so waiting costs time in proportion to the output. A regular expression is tried against all the pending output after each read, up to MaxBufferLength: the program on the other side decides what that output is, so give patterns a MatchTimeout (a RegexMatchTimeoutException then ends the wait) and keep MaxBufferLength no larger than needed.

Constructors

SshExpect(SshSession, Encoding?)

Drives session: reads its standard output, writes its standard input.

SshExpect(Stream, Stream, Encoding?)

Drives a program through its output and input streams.

Properties

Encoding

The encoding of the program's output and input.

MaxBufferLength

The most output kept while waiting for a match, in characters (1 MiB by default). When more arrives without a match, the oldest text is dropped, so a program that prints a lot without the expected text cannot exhaust memory.

NewLine

What SendLineAsync(string, CancellationToken) ends a line with: \n by default (a terminal turns it into what the program expects).

Pending

Output received but not yet consumed by a match.

Methods

ExpectAsync(string, CancellationToken)

Waits until the output contains text (an ordinal match).

ExpectAsync(Regex, CancellationToken)

Waits until the output matches pattern.

ReadLineAsync(CancellationToken)

Reads the next line of output: the text up to the next line feed, without it or a carriage return before it (a terminal ends lines with \r\n). Once the output has ended, the text left without a line feed is the last line, and then null.

SendAsync(string, CancellationToken)

Sends text to the program as it is.

SendLineAsync(string, CancellationToken)

Sends line followed by NewLine, as typing it and pressing Enter does.