loops - Using Variables inside one another Bash -

i running loop calls in variable file:

hostnames.txt 

the variables in file this:

export hostname_0=<hostname> export hostname_1=<hostname> export hostname_2=<hostname> 

i trying use them inside loop this:

. hostnames.txt f in {0..10}; ssh $hostname_'{$f}' if [$? !=0];    echo "unable ssh server $hostname_'{$f}'"    exit 1 fi 

however not reading value correctly, , i'm not sure i'm missing. love help.

you need build variable name , access ${!var}, e.g.:

. hostnames.txt f in {0..10};   hostnamevar=hostname_${f}   ssh ${!hostnamevar}   if [ $? -ne 0 ];     echo "unable ssh server ${!hostnamevar}"     exit 1   fi done