Reconnecting to SSH servers

In my work I'm often in situation where I want to restart remote server, and then immediately connect to it over ssh.

This can be done by repeating ssh HOST in shell, but it gets tedious.

I can also write a simple loop, like:

while true
do
    ssh HOST true &> /dev/null && break
    echo -n .
    sleep 1
done
echo
ssh HOST

But it always hides errors, and is not really elegant.

So, I wrote a simple tool that wraps this, and some additional logic: ressh.

It's usage is very simple:

=$ ressh -t 1 -i 12 10.2.3.4
2021-01-06 11:59:55 : Trying to connect to 10.2.3.4, with timeout: 1, initial: 12, sleep: 1 : ..........
2021-01-06 12:00:14 : (+10) ..
2021-01-06 12:00:19 : 12 tries passed, disabling hiding of errors.
2021-01-06 12:00:19 : #13 : Connection timed out during banner exchange
2021-01-06 12:00:21 : #14 : Connection timed out during banner exchange
2021-01-06 12:00:23 : #15 : Connection timed out during banner exchange
...
2021-01-06 12:00:34 : Successfully logged in, after 39 seconds.
Last login: Wed Jan  6 11:22:28 2021 from 10.2.3.1
12:00:34 depesz@test ~
=$

There are options to configure how long to wait for each ssh try (-t), how many times to try while hiding errors (-i), and how long to sleep between tries (-s):

=$ ./ressh -h
Usage:
    ./ressh [-t TIMEOUT] [-i INITIAL] [-s SLEEP] [-h] HOSTNAME
 
Options:
    -t - how many seconds to wait to connect, default: 5
    -i - after how many tries start showing errors, default: 30
    -i - how many seconds to sleep between tries, default: 1
    -h - show this help page
 
Description:
    ./ressh will try to connect to given HOSTNAME, retrying every couple of
    seconds, until it will succeed.

Hope you'll find it useful.

=$
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