ssh when invoked with variables form while loop not working

Question

I am running into an issue where I am comparing two files (alert.txt and env.txt) and based on common value, I am pulling complete line data from env.txt based on matching entry. I am reading these values into while loop and then invoking a function as follows. the ssh call is not working and also the while loop inside start_admin not working

#!/bin/bash
start_admin()
{
ssh -n -f $user@$host "sh -c 'cd $domain; ./script.sh > /dev/null 2>&1'"
while !(netstat -na | grep -E $host:$port|grep -E LISTEN) 2>/dev/null
sleep 30
do
echo "waiting"
done
echo "started"
}

grep -Ff alert.txt env.txt | (while IFS=" " read -r r1 r2 r3 r4 r5
do
user=$r2
host=$r3
domain=$r4
port=$r5
done
start_admin $user $host $domain $port
)

and contents of alert.txt is:
env2
env3

and that of env.txt is :
env1 user1 host1 /app/domain1/ port1
env2 user2 host2 /app/domain2/ port2
env3 user3 host3 /app/domain3/ port3

I could solve this with multiple if else loops, but that is not a desired solution, please guide me in right direction as to what is missing ?

Camusensei · Accepted Answer · 2021-01-14 22:27:13Z

1

Use join instead of grep here to avoid false positives
Because your while read loop completes before you run start_admin, you only launch it once (done should be AFTER start_admin)
In start_admin, don't use $user, $host and so on, use $1, $2 (or use them but don't pass them as parameters when calling the function)

I'm not sure exactly what you try to achieve, but here is a revised version already.

#!/bin/bash
start_admin()
{
  sanitized_domain=${domain//'"'/'\"'}
  ssh -n -f "$user@$host" "sh -c 'cd \"$sanitized_domain\"; ./script.sh >/dev/null 2>&1'"
  while ! netstat -na | grep -q " $host:$port .*LISTEN"; do
    echo waiting
    sleep 30
  done
  echo started
}

join alert.txt env.txt | while IFS=' ' read -r env user host domain port; do
  start_admin
done
)

edited Jan 14, 2021 at 22:27

answered Jan 14, 2021 at 14:50

Camusensei

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1 Comment

Novice Over a year ago

thanks @Camusensei, I got the direction and with the above revised solution, I am able to do the desired task.

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