bash script for executing commands on multiple server

Question

I want a script which will restart the defined services on their respective servers. I want to pass parameter as below to the script: eg:

sh execute.sh 
Enter your server and service list: [server1:nginx,mysql],[server2:mysql,apache],[server3:mongodb,apache]

By this input the script should verify and start the services on the respective servers. I am able to do this on a single server by declaring variables.

#!/bin/bash

Instance_Name=server1
Service_Name=(nginx php-fpm mysql)
SSH_USER=admin
SSH_IDENT_FILE=~/credentials/user.pem

len=${#Service_Name[*]} 
i=0
while [ $i -lt $len ]; do 
service=${Service_Name[$i]}
ssh -i $SSH_IDENT_FILE -o StrictHostKeyChecking=no $SSH_USER@$Instance_Name 'service $service restart'
done

Now I don't have an idea to move forward. Please let me know if my question is unclear. Thanks in advance.

What about wrapping it in a big for looping through the name of servers? — fedorqui
– fedorqui, Commented Oct 15, 2013 at 9:01
For example: while read $server; do ... (execute your script with $server parameter) .... done < list_of_servers — fedorqui
– fedorqui, Commented Oct 15, 2013 at 9:05
The array declaration is wrong. You don't have to put comma unless you want those to be part of the elements in the array. Say Service_Name=(nginx php-fpm mysql) instead. — devnull
– devnull, Commented Oct 15, 2013 at 9:07
But as I told you before I want user input like this format: [server1:nginx,mysql],[server2:mysql,apache],[server3:mongodb,apache] — linuxnewbee
– linuxnewbee, Commented Oct 15, 2013 at 9:08

LMC · Accepted Answer · 2013-10-15 19:42:46Z

1

Parse your input parameters

# create an array of server:services
a=($(echo "$1" | gawk 'BEGIN { FS="[]],[[]" } ; { print $1, $2, $3 }' | tr -d '[]'))
# add a for loop here to iterate values in array with code below
for var in "${a[@]}" ; do
  # get server name
  server1=$(echo $var | cut -d ':' -f1)
  # get your services as space separated
  servs1="$(echo $var | cut -d ':' -f2 | tr ',' ' ')"
  # loop your services
  for s in $servs1; do
    ssh $server1 "service $s restart"
  done
done

If you like bash programming or have to learn it this is the 'bible' to me Advanced Bash-Scripting Guide An in-depth exploration of the art of shell scripting Mendel Cooper http://www.tldp.org/LDP/abs/html/

edited Oct 15, 2013 at 19:42

answered Oct 15, 2013 at 13:39

LMC

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4 Comments

linuxnewbee Over a year ago

thanks for the great help but still I am confuse how to add a loop for the first array. I am not a program though. Can you please help me by solving the puzzle.

linuxnewbee Over a year ago

Hi Luis, thanks for the quick response. Sure I will continue my reading on bash programming. But the above script you wrote is working for only first section of the user input [server1:nginx,mysql],[server2:mysql,apache],[server3:mongodb,apache] i.e. for server1 how to do with others? means server2 and 3

LMC Over a year ago

Fixed. Sorry :p forgot to other changes after adding the for loop.

linuxnewbee Over a year ago

Thanks Luis for your help my problem got solved. I have edited your script and now it's working fine for me.

Vlad · Accepted Answer · 2013-10-15 17:17:21Z

Try this?

#!/bin/bash
SSH_IDENT_FILE=~/credentials/user.pem
SSH_USER=admin

# tells 'for' to read "per line"
IFS='
'

for line in $(
# read input from 1st command-line arg (not stdin)
echo "$1"|\
# remove all services except (nginx php-fpm mysql)
sed 's/\([:,]\)\(\(nginx\|php-fpm\|mysql\)\|[^]:,[]\+\)/\1\3/g'|\
# make it multi-line:
#    server1 svc1 svc2
#    server2 svc1
sed 's/\[[^]:]*:,*\]//g;s/\],*$//;s/\],*/\n/g;s/[:,]\+/ /g;s/\[//g'|\
# make it single-param:
#    server1 svc1
#    server1 svc2
#    server2 svc1
awk '{for(i=2;i<=NF;i++)print $1" "$i}'
);do
        IFS=' ' read Instance_Name service <<< $line
        echo ssh -i $SSH_IDENT_FILE -o StrictHostKeyChecking=no $SSH_USER@$Instance_Name "service $service restart"
done

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