41

Is there a way to remote tail 2 files?

I have two servers(a and b) behind a load balancer and I would like to do something like this if possible:

tail -f admin@serverA:~/mylogs/log admin@serverB:~/mylogs/log

Thanks!

  • Why did you erase the answer? – Pablo Fernandez Feb 13 '10 at 0:20
  • mostly because it did not work :-) – mat Feb 13 '10 at 0:20
  • @mat Oh I was just about to try it :). Thanks anyways! – Pablo Fernandez Feb 13 '10 at 0:25
  • it does not work because the <(foo) construct will wait for the inner command to finish before being replaced by a pipe in the original command line from which the software will be able to read, and, tail would never finish :-) – mat Feb 13 '10 at 0:28

12 Answers 12

31

This worked for me:

ssh -n user@hostname1 'tail -f /mylogs/log' &
ssh -n user@hostname2 'tail -f /mylogs/log' &
  • Yep, that's how i do it, except i usually have multiple gnome-terminals open, each with one session inside it – Tom O'Connor Feb 13 '10 at 8:27
  • 1
    Is there a way to do this without opening multiple independent ssh sessions? – tgies Mar 20 '13 at 1:09
  • 8
    But this does not allow you to stop the tailing with Ctrl+C. – sorin Apr 28 '14 at 16:40
  • @sorin to terminate the processes, just bring each one back to the foreground with fg; then you can ctrl+c it. You'd do that once for each tail you have running. Or you could pkill -f ssh to target all of them of them at the same time. – Dale Anderson Nov 22 '17 at 18:33
34

My preferred option is to go with multitail. I'd run something like:

multitail -l 'ssh user@host1 "tail -f /some/log/file"' -l 'ssh user@host2 "tail -f /some/log/file"'
  • 1
    Thanks! I was looking for an example of how to use multitail over ssh / on remote hosts! – Noah Sussman Feb 25 '15 at 16:07
  • Multitail is a far more robust solution. – obfk Apr 6 '15 at 18:14
  • our website has more than 10 web nodes, and multitail fails in the first try with the error Operation not permitted, with 2 3 web nodes, it's ok – Hieu Vo May 28 '15 at 11:29
  • I also get the Operation not permitted, any clues? – Erik Aigner Oct 30 '15 at 11:05
7

You can use fabric to tail several hosts (and also grep results, if needed):

$ fab -P -u 'USER' -p 'PASSWORD' --linewise -H host1,host2,host3 -- tail -f /path/to/my/log.log | grep ERROR
6

I was thinking it might also be possible to use:

ssh -f user@hostname1 "tail -f /var/log/file" > /tmp/somefile &
ssh -f user@hostname2 "tail -f /var/log/file" > /tmp/somefile &

The -f option after ssh allows you to enter a password before it runs in the background. Then you could have the line-by-line results in a single file and running:

tail -f /tmp/somefile

Would give you a little more control over the current "tail" command in case you wanted to use other tail options for displaying output.

6

Check out this answer on stackoverflow -- it uses dsh and tail -f.

5

Take a look at multitail. Just like the examples above, you can give it as a command to ssh, and then you will end up with one screen displaying (and buffering for easy scrollbacks) multiple logs. It also does coloring, which is very useful for spotting anomalies.

2

Parallel ssh has a nice solution for this:

pssh -t0 -H 'host-01 host-02 host-03 host-04' -P tail -f /var/log/app.log
  • -t0 disables the connection timeout, otherwise pssh closed the connection
  • -H '<host>...' is the list of hosts to run the command
  • -P is to enable printing the stdout of each host
  • tail -f /var/log/app.log can be any command that your remote shell can run
1

What would you say about something like this? http://gist.github.com/303175

1

Just a weird solution, but it works!:

Screen 1

ssh user@hostname1 "tail -f /var/log/file" > /dev/pts/6

Screen 2

ssh user@hostname2 "tail -f /var/log/file" > /dev/pts/6
  • this will work, outputting lines on the /dev/pts/6 terminal (to find out your own terminal : execute: who am i and it will show it to you.) – Olivier Dulac May 10 at 16:56
1

You can checkout dbitail.

A Java tool I created, able to read local and distant log files using SSH. It is fairly simple to use.

Some more explanations: https://github.com/pschweitz/DBITail/wiki

Just download version corresponding to your operating system, of native jar release executable within your Java Runtime (requires java 8_40 or higher):

https://github.com/pschweitz/DBITail/releases

You can find a complete documentation (embedded with and I Github's page as well)

Philippe

0

or you can use screen to create two terminals and then split them.

SSH into the first host you want to tail the log file of and before running tail, enter screen.

Then tail the file on this host.

CTRL+A, c will create a new screen or window. From this new window ssh into the 2nd host and tail the file there.

Now to create the split screen

CTRL+A, SHIFT+S, this will create a split screen with current shell in the top part and the bottom part empty. To switch to the bottom part and put the first screen within it,

CTRL+A, TAB, this will move you to the bottom part. Now to bring your first SSH session into this area:

CTRL+A, " (quote symbol) and select the first session and hit enter.

I realize this may look like a lot of gymnastics, and it is, but you do get use to it once you use it a few times.

Here is a really good tutorial or quick reference to screen's commands: http://www.pixelbeat.org/lkdb/screen.html

Additionally, you can create a .screenrc file so that much of what I described can be automated the first time you enter screen.

Another nice thing about this is that you can just close your session and resume it some place else. For example, you're at work and you have some monitoring going on. You can just close your session without logging out, and resume when you get home or to another location.

0

You can Tail files remotely using bash and rsync, I"m using it and it is a great bash script have a look at the following tutorial

Tail files remotely using bash and rsync

  • Link doesn't work – czerasz Feb 19 '16 at 12:57

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