[SOLVED] Push multiple commands through ssh to remote server

Anand R · 05-25-2018, 02:23 AM

My requirement is that I want to push ssh command to remote server, So that will check current and installed kernel version on the remote server and have to reboot.

I have tried “su --session-command” combination also.

ssh anand@remote_host “su -lc ‘if [ “rpm -q kernel | tail -1” == “kernel-$(uname -r)” ]; then echo “System is already running with latest kernel version”; else echo “reboot”; fi’”

Its taking variables where I pushing the command but I should take variables from remote server.

pan64 · 05-25-2018, 05:11 AM

probably protecting $ with \ will help you.

MadeInGermany · 05-27-2018, 04:35 AM

Make a separate remote_script like

Code:

#!/bin/bash
if [ "$(rpm -q kernel | tail -1)" == "kernel-$(uname -r)" ]
then
  echo "System is already running with latest kernel version"
else
  echo "reboot"
fi

that you can test on the remote server.
(Maybe add a further indirection level of su -c to the remote_script. Better work with keys and switch to root in ssh like the following.)
The following is a script that pushes/runs the remote_script to/on each remote host:

Code:

for h in remote_host1 remote_host2
do
  ssh root@"$h" /bin/bash -s < remote_script
done

Having a separate remote script saves another level of indirection i.e. extra escapes.

Turbocapitalist · 05-27-2018, 04:50 AM

Also, it looks like Vista8 might be mutilating the quotes, too. You need plain single ' and double " quotes not fancy ones like ‘ ’ and “ ” because the fancy ones are invalid.

MadeInGermany · 05-27-2018, 07:47 AM

Ah yes, and one command within the test was not in $( ) - I changed my post#3.

Anand R · 06-03-2018, 10:28 PM

Quote:

Originally Posted by pan64

probably protecting $ with \ will help you.

Can you help me using $with \ in appropriate place? I have tried, its not working.

Am tried with your answer and am getting below error.

ssh -t anandr@xxx.xxx.x.xx $$"su -lc 'if [ "`rpm -q kernel | tail -1`" == "kernel-$(uname -r)" ]; then echo "System is already running with latest kernel version"; else echo "reboot"; fi'"$
Password:
bash: System: command not found
Connection to xxx.xxx.x.xx closed.

Turbocapitalist · 06-04-2018, 01:09 AM

Just pay lots of attention to the quotes, work your way in from the outside to the inside and make sure they are balanced. Quotes of the same kind need to be escaped when on the inside:

Code:

ssh -t anandr@xxx.xxx.x.xx "su -lc 'if [ \"\$(rpm -q kernel | tail -n 1)\" == \"kernel-\$(uname -r)\" ]; then echo \"System is already running with latest kernel version\"; else echo reboot; fi'"

or this would be more simple

Code:

ssh -t anandr@xxx.xxx.x.xx "if [ \"\$(rpm -q kernel | tail -n 1)\" == \"kernel-\$(uname -r)\" ]; then echo \"System is already running with latest kernel version\"; else echo sudo reboot; fi"

pan64 · 06-04-2018, 01:46 AM

you need to protect $ so you need to prepend a \: kernel-\$(uname -r)
But as it was already suggested you need to check quotation.
see for example here: https://unix.stackexchange.com/quest...uotes-in-shell
or here: http://wiki.bash-hackers.org/syntax/quoting

Anand R · 06-04-2018, 02:30 AM

Quote:

Originally Posted by pan64

you need to protect $ so you need to prepend a \: kernel-\$(uname -r)
But as it was already suggested you need to check quotation.
see for example here: https://unix.stackexchange.com/quest...uotes-in-shell
or here: http://wiki.bash-hackers.org/syntax/quoting

Thank you pan64 and Thank you all.

It's working perfectly what I expected.

MadeInGermany · 06-04-2018, 06:36 AM

A bit more sophisticated is

Code:

# cat remote_script
#!/bin/bash
PATH=/bin:/usr/bin:/sbin:/usr/sbin
rev=`uname -r`
rev=${rev%%[-.][!0-9]*}

#for kernel in `rpm -qa | egrep '^kernel-((default|PAE)-)?[0-9]' | sort`
# rpm --last is more reliable than an alpabetical sort
for kernel in `rpm -qa --last | egrep '^kernel-((default|PAE)-)?[0-9]' | awk '{print $1}' | tac`
do
  krev=${kernel##*[!0-9]-}
  krev=${krev%%[-.][!0-9]*}
  if [[ $krev == $rev* ]]
  then
    printf "*$krev\n"
  else
    printf " $krev\n"
  fi
done
if [[ $krev != $rev* ]]
then
  echo "reboot needed"
fi

# ssh remotehost /bin/bash -s < remote_script
 2.6.32-696.13.2
*2.6.32-696.16.1
 2.6.32-696.23.1
reboot needed

pan64 · 06-04-2018, 07:17 AM

additionally you only need to remote execute the rpm command, the other parts of the script can run on the local host (like grep):

Code:

ssh remotehost "rpm -qa" | egrep  | sort | while read kernel
do
 ....
done

or something similar