scripts/mosh: Add --no-init option to disable alternate screen mode

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

Closes #384. Closes #2.

man/mosh.1

@@ -128,6 +128,12 @@ only port that is forwarded through a firewall to the
 server. Otherwise, \fBmosh\fP will choose a port between 60000 and
 61000.
 
+.TP
+.B \-\-no\-init
+Do not send the \fBsmcup\fP initialization string and \fBrmcup\fP
+deinitialization string to the client's terminal. On many terminals
+this disables alternate screen mode.
+
 .SH ESCAPE SEQUENCES
 
 The escape sequence to shut down the connection is \fBCtrl-^ .\fP

scripts/mosh

@@ -48,6 +48,8 @@ my $port_request = undef;
 
 my $ssh = 'ssh';
 
+my $term_init = 1;
+
 my $help = undef;
 my $version = undef;
 
@@ -72,6 +74,8 @@ qq{Usage: $0 [options] [--] [user@]host [command...]
                                 (example: "ssh -p 2222")
                                 (default: "ssh")
 
+        --no-init            do not send terminal initialization string
+
         --help               this message
         --version            version and copyright information
 
@@ -104,6 +108,7 @@ GetOptions( 'client=s' => \$client,
 	    'n' => sub { $predict = 'never' },
 	    'p=s' => \$port_request,
 	    'ssh=s' => \$ssh,
+	    'init!' => \$term_init,
 	    'help' => \$help,
 	    'version' => \$version,
 	    'fake-proxy!' => \my $fake_proxy ) or die $usage;
@@ -281,6 +286,7 @@ if ( $pid == 0 ) { # child
   # Now start real mosh client
   $ENV{ 'MOSH_KEY' } = $key;
   $ENV{ 'MOSH_PREDICTION_DISPLAY' } = $predict;
+  $ENV{ 'MOSH_NO_TERM_INIT' } = '1' if !$term_init;
   exec {$client} ("$client @cmdline |", $ip, $port);
 }
 

src/terminal/terminaldisplayinit.cc

@@ -146,7 +146,9 @@ Display::Display( bool use_environment )
     posterize_colors = ti_num( "colors" ) < 256;
     */
 
-    smcup = ti_str("smcup");
-    rmcup = ti_str("rmcup");
+    if ( !getenv( "MOSH_NO_TERM_INIT" ) ) {
+      smcup = ti_str("smcup");
+      rmcup = ti_str("rmcup");
+    }
   }
 }