How do I tell which users are connected to a shared tmux socket?

Question

I have created a shared socket for tmux to use.

tmux -S /tmp/pair

Then I have a 2nd user attach to the socket.

tmux -S /tmp/pair attach

How do I tell from the first session, the one that created the socket, tell that the 2nd user is connected?

I'm guessing it would be something from the lsof command.

From inside tmux? `Ctrl-b D` – hroptatyr Sep 20 '12 at 07:30 — hroptatyr, Sep 20 '12 at 07:30
@hroptatyr You mean ` D`, yes? :/ – Piotr Dobrogost Jul 18 '17 at 21:15 — Piotr Dobrogost, Jul 18 '17 at 21:15

score 25 · Accepted Answer · answered Sep 20 '12 at 16:52

25

You can use the list-clients command. By itself, it displays all clients connected to the server. If you specify a session with the -t option, it shows clients attached to the named session.

answered Sep 20 '12 at 16:52

chepner

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score 14 · Answer 2 · answered May 19 '16 at 09:13

14

Like another user said in comments <prefix> D will list all the sessions but keep in mind that pressing enter will detach that client (which may or may not be what you want)

answered May 19 '16 at 09:13

Shubham Chaudhary

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Attention: That's Shift-D, without shift, you get detached from the session yourself. – phant0m Nov 20 '17 at 08:23

score 0 · Answer 3 · answered Feb 28 '19 at 21:56

The answers given (Ctrl-b D or Ctrl-b : list-clients RET) will give you a list of clients with their (virtual) tty terminal and window size, but does NOT tell you the associated username. From outside of a tmux session, you can also use "tmux -S /tmp/pair list-clients"

One method to list actual users that are connected is to run lsof on the named socket, ie: "lsof /tmp/pair"

Or you can use the 'who' command to view a listing of users associated with the virtual terminals. If you are just differentiating between your own connections, you can use an alis to filter that: "who | awk '{print $2,$NF}' |grep -v '(:[0-9]'"

Here's a quick Perl script that puts the tmux and 'who' outputs together. For usage with shared sockets, pass the socket file as the sole argument, ie: "tmux_ls.pl /tmp/shared":

my $sock="";
$sock = "-S ".$ARGV[0] if $ARGV[0];

my $clients = `tmux $sock list-clients`;

# Use open to loop like a file
open my $fh, '<', \$clients or die $!;

printf("%-10.10s\t%-10.10s\t%-10.10s\t%-16.16s\t%s\n", "Session", "TTY", "Username", "Timestamp", "Origin");
while(<$fh>) {
    my @cols = split(' ');
    my ($tty) = $cols[0] =~ /^\/dev\/(pts\/\d+)/;
    my $session = $cols[1];
    my $who = `who | grep $tty`;
    my @whoc = split(' ',$who);

    printf("%-10.10s\t%-10.10s\t%-10.10s\t%-16.16s\t%s\n", $session,$tty,$whoc[0], "$whoc[2] $whoc[3]", $whoc[4]);
}

How do I tell which users are connected to a shared tmux socket?

3 Answers3