Screen is amazing, of course, but I don't want to have to think about it. I often ssh to a machine, start doing a bunch of stuff, and then think "gosh, I wish I had thought to start a screen session before doing all that so I could reconnect to this from home later".
I'd like to have screen automatically started whenever I log in to a machine. And when I get disconnected, I want to be able to immediately and simply reconnect without fussing with "screen -ls" and "screen -dr".
I have a script that implements one solution to this problem which I'll post as an answer. I'm interested to see other approaches.
Use the following, ssc
, instead of ssh
. If you just do "ssc remote.com
" then it will list existing screen sessions. Give it a 3rd argument and it will connect to that screen session, or create it and connect to it. Either way, if you get disconnected you can just do "up-arrow, enter" in the shell to reconnect. Zero knowledge of screen required!
Edit: Thanks to @klochner for extending this to handle arbitrary ssh options. You can now use this just like ssh!
#!/usr/bin/env perl
# Use 'ssc' (this script) instead of 'ssh' to log into a remote machine.
# Without an argument after the hostname it will list available screens.
# Add an argument after the hostname to attach to an existing screen, or
# specify a new screen. Eg, ssc remote.com foo
# The numbers in front of the screen tag can usually be ignored.
# ssh option parsing by @klochner
my $optstring = "";
while ($val = shift) {
if ($val =~ /^-\w$/) { $optstring .= " ".$val.(shift); }
elsif ($val =~ /^-\w+$/) { $optstring .= " ".$val; }
elsif ($machine) { $tag = $val; }
else { $machine = $val; }
}
if (!$machine) {
print "USAGE: ssc [ssh options] remote.com [screen name]\n";
} elsif (!$tag) {
@screens = split("\n", `ssh $optstring $machine screen -ls`);
for(@screens) {
if(/^\s*(\d+)\.(\S+)\s+\(([^\)]*)\)/) {
($num, $tag, $status) = ($1, $2, $3);
if($status =~ /attached/i) { $att{"$num.$tag"} = 1; }
elsif($status =~ /detached/i) { $att{"$num.$tag"} = 0; }
else { print "Couldn't parse this: $_\n"; }
# remember anything weird about the screen, like shared screens
if($status =~ /^(attached|detached)$/i) {
$special{"$num.$tag"} = "";
} else {
$special{"$num.$tag"} = "[$status]";
}
}
}
print "ATTACHED:\n";
for(sort { ($a=~/\.(\w+)/)[0] cmp ($b=~/\.(\w+)/)[0] } keys(%att)) {
($tag) = /\.(\w+)/;
print " $tag\t($_)\t$special{$_}\n" if $att{$_};
}
print "DETACHED:\n";
for(sort { ($a=~/\.(\w+)/)[0] cmp ($b=~/\.(\w+)/)[0] } keys(%att)) {
($tag) = /\.(\w+)/;
print " $tag\t($_)\t$special{$_}\n" unless $att{$_};
}
} else {
system("ssh $optstring -t $machine \"screen -S $tag -dr || screen -S $tag\"");
}
Btw, there's a trick to forcing an ssh session to exit and give you back your local terminal prompt when you lose network connectivity:
https://superuser.com/questions/147873/ssh-sessions-in-xterms-freeze-for-many-minutes-whenever-they-disconnect