using ssh to execute dozens of shell commands in shell script

hilou · 04-17-2016, 11:12 PM

Hi All,

I recently need to write a shell script to restart tomcat. So I need to login to a remote machine and kill the java process, then export JAVA_HOME env, and run startup.sh.

I have tried the below 3 methods to accomplish this:

1.

Code:

ssh user@ip "sh DIR/kill.sh $parameter; export JAVA_HOME='/opt/..'; sh DIR/startup.sh"

2.

Code:

ssh user@ip <<EOF
sh DIR/kill.sh $parameter
export JAVA_HOME='/opt/..'
sh DIR/startup.sh
exit
EOF

3.

Code:

ssh user@ip 'bash -s' < a.sh $para

a.sh

Code:

sh DIR/kill.sh $1
export JAVA_HOME='/opt/..'
sh DIR/startup.sh

All the 3 methods have it's own limitation:
the first one doesn't work. I don't know why it just run to kill.sh, the startup.sh is not executed.

the second one report some need TTY errors like below:
Pseudo-terminal will not be allocated because stdin is not a terminal.
TERM environment variable not set.

the third method seems works fine, But this is not what I want. I don't want to create an extra scripts to do this.

So my question is WHAT'S THE BEST WAY TO SSH TO REMOTE TO EXECUTE A BATCH OF COMMANDS? WHAT'S THE MOST ELEGANT AND RIGHT WAY TO DO HTIS?

Thank you in advance.

grail · 04-18-2016, 12:12 AM

Well personally, as soon as you say a batch of commands, my first response would be to write a script, but for an unexplained reason you do not wish to go that way??

hilou · 04-18-2016, 05:23 AM

Quote:

Originally Posted by grail

Well personally, as soon as you say a batch of commands, my first response would be to write a script, but for an unexplained reason you do not wish to go that way??

Yes, I prefer solve the problem in one script.

pan64 · 04-18-2016, 05:34 AM

in case 2 TERM is not set, that is normal. You may try to set it manually and probably helps. Would be nice to know if you really need a terminal (or not).

sundialsvcs · 04-18-2016, 07:44 PM

Quote:

Originally Posted by hilou

Yes, I prefer solve the problem in one script.

But, here's something to think about:

Quote:

Originally Posted by The Las Vegas principle:

What happens in Las Vegas, stays in Las Vegas."

In other words, "if you are doing anything substantial on a remote system, then there should be a 'one script' on that system." Not on a remote machine somewhere far-distant. While the distant machine may initiate the process (by means of "ssh," "rsync," or what-have-you ...), when the time comes to "finally get to work," the code that gets the job done should reside on the remote, and be executed there.

jpollard · 04-18-2016, 07:46 PM

Depending on the target system, most of that has already been done for you.

If it is systemd based, just doing a "systemctl stop tomcat; systemctl start tomcat" will do it.

But look to see how the target system starts/stops the service already.

Habitual · 04-19-2016, 04:51 AM

Quote:

Originally Posted by jpollard

If it is systemd based, just doing a "systemctl stop tomcat; systemctl start tomcat" will do it.

Yeah, I wondered about that also.
What's with the archaic "sh DIR/startup.sh" stuff on modern systems with modern tomcat?

And if it's not systemd, doing a "service tomcat6 restart" will do the job.
Hilou: system-level controls will allow you to remotely restart tomcat.
so, user@ip would have to be allowed via visudo to execute "service". Once that's enabled,

Code:

ssh user@ip "service tomcat restart"

should do it.

"sh DIR/startup.sh?

Code:

echo "$DIR" #BIG FAT NULL VALUE

Where you'd get these scripts? You didn't write them.
What version of Tomcat on what distro?
How was it installed?
What have you read? and Where?

"Dozens of shell commands" on just one host or a 1000?
You tell me what makes more sense.

bigearsbilly · 04-20-2016, 04:25 AM

two useful tools I use for administering multiple servers are:

copy execute on multiple servers
http://www.garbled.net/clusterit.html

multiple xterms:
https://github.com/duncs/clusterssh/wiki

clusterssh may be included on your distro