6 *) echo >&2 "usage: $0 {start|stop|restart|status} HOST"; exit 1 ;;
12 echo "$*" >"$file.new"
13 mv "$file.new" "$file"
16 runssh
() { ssh -T
-oControlPath
="./$host.ctrl" "$@"; }
20 ## Shut down an existing connection if there is one.
21 if [ -S
"$host.ctrl" ]; then
22 runssh
-Oexit
"$host" >/dev
/null
2>/dev
/null ||
:
25 ## If there's still a socket, then work out what to do.
26 if [ -e
"$host.ctrl" ]; then
28 ## If the connection's still running then we have a problem.
29 if runssh
-Ocheck
"$host" >/dev
/null
2>/dev
/null
; then
30 echo >&2 "$0: failed to kill existing connection to $host"
34 ## Remove the stale socket.
41 ## Initial shutdown protocol.
42 writefile
"$host.state" stopping
43 if [ -f
"$host.pid" ]; then kill $
(cat "$host.pid") 2>/dev
/null ||
:; fi
46 ## Clobber the existing connection, if there is one.
50 rm -f
"$host.state" "$host.pid"
55 ## There doesn't seem to be a better way of getting this. :-(
56 read pid
<"$host.daemonpipe"
57 rm -f
"$host.daemonpipe"
60 trap 'rm -f "$host.pid"; stopit' EXIT INT TERM
61 writefile
"$host.pid" "$pid"
66 ## Not waiting on a pipe yet.
69 ## Keep the connection up for as long as we can.
70 while [ -f
"$host.pid" ]; do
72 ## Maybe back off before trying another connection.
78 writefile
"$host.state" \
79 "wait until $(date -d+${delay}sec +"%Y-
%m-
%d
%H
:%M
:%S
%z
")"
82 if [ $delay -gt
120 ]; then delay
=120; fi
86 ## Prepare a pipe so that we can wait for SSH to finish. This is a
90 *) kill $kidcat >/dev
/null
2>&1 ||
:; kidcat
=nil
;;
92 rm -f
"$host.pipe"; mkfifo -m600
"$host.pipe"
93 cat $host.pipe
>/dev
/null
& kidcat
=$
!
95 ## Start a new connection.
96 writefile
"$host.state" starting
97 if ! runssh
-MNnf
"$host" >"$host.pipe"; then continue; fi
98 if ! runssh
-Ocheck
"$host" >/dev
/null
2>&1; then
99 echo "connection to $host apparently stillborn"
102 writefile
"$host.state" connected
105 ## Wait until it gets torn down.
106 wait $kidcat >/dev
/null
2>&1 ||
:
109 writefile
"$host.state" disconnected
115 ## If there's already a connection then we have nothing to do.
116 if runssh
-Ocheck
"$host" >/dev
/null
2>/dev
/null
; then
117 echo >&2 "$0: already connected to $host"
121 ## Start a daemon which makes connections for us. This is remarkably
123 rm -f
"$host.daemonpipe"; mkfifo -m600
"$host.daemonpipe"
124 { daemon
& echo $
! >"$host.daemonpipe"; } 2>&1 | logger
-pdaemon.notice
&
131 restart
) stopit
; startit
;;
133 if [ -f
"$host.state" ]
134 then cat "$host.state"
139 echo >&2 "usage: $0 {start|stop|restart|status} HOST"