No return after executing passwd command using ssh in script

Question

I have one script which reads hosts IP from /etc/hosts file, do ssh and update the passwords there for the given user. However, the script is closed after setting password for the first host and not able to set password for rest of the hosts. Please find below files-

/etc/hosts file-

172.x.x.x host1
172.x.x.x host2
172.x.x.x host3

Script I am using is as-

key=$1  
user=$2  
password=$3  
filename='/etc/hosts'  
while IFS= read -r line; do 
   IFS=' ' read -r -a array <<< $line
   ssh -i $key centos@${array[0]} "echo "$password" | sudo passwd $user --stdin"  
done <$filename

Script is simple. but it is getting closed after setting password for host1 from file. Does anyone has any idea, what I am missing?

Kaushik Nayak · Accepted Answer · 2017-07-04 14:52:12Z

2

By default ssh reads from stdin which is your input file.ssh consumes the rest of the file and your while loop terminates.So try using

       ssh -n

answered Jul 4, 2017 at 14:52

Kaushik Nayak

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Comments

l0b0 · Accepted Answer · 2017-07-04 14:51:25Z

0

What is happening is that ssh is swallowing all of the standard input. The way to avoid that in general is to use a different file descriptor for your input, for example:

while IFS= read -u 9 -r line
do
    […]
done 9< "$filename"

However, this approach to changing authentication is really quite insecure, and I would strongly recommend moving to using public keys instead.

answered Jul 4, 2017 at 14:51

l0b0

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Comments

Raman Sailopal · Accepted Answer · 2017-07-05 08:15:22Z

0

Using awk would help overcome any issues:

awk -v key=$1 -v usa=$2 -v pass=$3 '{system("ssh -i "key" centos@"$1" \"echo "pass" | sudo passwd "usa" --stdin\"")}' $filename

Assign you passed parameters as awk variables with -v and then use these to construct the ssh command to be executed with awk's system function

edited Jul 5, 2017 at 8:15

answered Jul 4, 2017 at 14:56

Raman Sailopal

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3 Comments

Yogesh Jilhawar Over a year ago

you have kept filename at the end. What significance it has?

Raman Sailopal Over a year ago

Apologies, should be $filename

Raman Sailopal Over a year ago

Apologies, I made a mistake setting up the pass variable. Try it now. Make sure that this is set up in a script with the filename variables set to /etc/hosts and 3 parameters passed for the key, username and password

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