Receive from an SSH Channel Until a Pattern Matches

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Demonstrates the Chilkat Ssh.ChannelReceiveUntilMatch method, which receives text until the accumulated text matches a pattern. The arguments are the channel number, the pattern, the charset, and whether matching is case-sensitive. Existing buffered text is checked before waiting for more network data.

Important: Set the ReadTimeoutMs property before calling this method. It defaults to 0, meaning no limit, so without it the call waits forever if the received data never contains a match.

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // Demonstrates the Ssh.ChannelReceiveUntilMatch method, which receives text until the
    // accumulated text matches a pattern.  The 1st argument is the channel number, the 2nd is the
    // pattern, the 3rd is the charset, and the 4th selects case-sensitive matching.  The pattern
    // supports literal characters plus "*", which matches zero or more characters.

    const ssh = try chilkat.Ssh.init();
    defer ssh.deinit();

    const ssh_port = 22;
    ssh.connect("ssh.example.com", ssh_port) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    // Normally you would not hard-code the password in source.  You should instead obtain it
    // from an interactive prompt, environment variable, or a secrets vault.
    const password = "mySshPassword";

    ssh.authenticatePw("mySshLogin", password) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    const channel_num = ssh.openSessionChannel();
    if (channel_num < 0) {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    }

    // Start a shell WITHOUT requesting a PTY.  Without a PTY the shell sees it is connected to a
    // raw data pipe and enters non-interactive mode: it suppresses the command prompt, does not
    // echo typed commands back, and skips interactive login scripts.  The output is therefore
    // clean and easily parseable -- but because no prompt is ever sent, code must not wait for
    // one.  Instead, have each command print a predictable marker, or wait for EOF / channel close.
    ssh.sendReqShell(channel_num) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    // There is no prompt to wait for, so make the command itself announce when it has finished
    // by echoing a marker after it.
    ssh.channelSendString(channel_num, "ls -l /tmp; echo DONE_MARKER\n", "utf-8") catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    // IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
    // which means no limit -- without it, this call waits forever if the received data never
    // contains a match.
    ssh.setReadTimeoutMs(15000);

    // Receive until the marker appears in the output.
    const case_sensitive = false;
    ssh.channelReceiveUntilMatch(channel_num, "DONE_MARKER", "utf-8", case_sensitive) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    const output = ssh.getReceivedText(alloc, channel_num, "utf-8") catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("{s}\n", .{output});

    ssh.disconnect();
}