bash while loop using echo as the loop counter

Question

hello I have a command

echo $(ssh [email protected] 'zfs list -o name -t snapshot | grep tank/dema@Daily_$(date +"%Y-%m-%d") | wc -l')

this returns a integer value I need to while loop over it but can't seem to figure out who to do that.

while echo $(ssh [email protected] 'zfs list -o name -t snapshot | grep tank/dema@Daily_$(date +"%Y-%m-%d") | wc -l') -g 1; do

echo stuff

done

What is the intention of the -g param? And what is the output of the command echo $(ssh [email protected] 'zfs list -o name -t snapshot | grep tank/dema@Daily_$(date +"%Y-%m-%d") | wc -l') -g 1 and echo $(ssh [email protected] 'zfs list -o name -t snapshot | grep tank/dema@Daily_$(date +"%Y-%m-%d") | wc -l') — R Yoda
– R Yoda, Commented Apr 16, 2015 at 6:46
What do you mean by "while loop over it"? Do you need to call that long command on each iteration? Do you iterate until the integer is zero, or what? — cdarke
– cdarke, Commented Apr 16, 2015 at 6:53
Sorry the output of the command is a integer like 6 or 10 ect. I want to loop over it while output > 1. Also it needs to call said command each loop to make sure it's still greater then 1. Thanks for the help. — Kent
– Kent, Commented Apr 16, 2015 at 6:54
while keeps looping as long as that condition is true (returns a 0 exit status). So what exactly do you observe when executing your code above? That the code inside of the while loop is never executed? — R Yoda
– R Yoda, Commented Apr 16, 2015 at 7:08

Pravin Junnarkar · Accepted Answer · 2015-04-16 08:24:46Z

1

Hi You can try like this,

declare -i value
value=`echo $(ssh [email protected] 'zfs list -o name -t snapshot | grep tank/dema@Daily_$(date +"%Y-%m-%d") | wc -l')`
while [ "$value" -gt 1 ]; do
    echo stuff
    value=`echo $(ssh [email protected] 'zfs list -o name -t snapshot | grep tank/dema@Daily_$(date +"%Y-%m-%d") | wc -l')`
done

OR we can use it like,

declare -i value
while : ; do
  value=`echo $(ssh [email protected] 'zfs list -o name -t snapshot | grep tank/dema@Daily_$(date +"%Y-%m-%d") | wc -l')`
  [[ "$value" -gt 1 ]] || break
  echo stuff
done

edited Apr 16, 2015 at 8:24

answered Apr 16, 2015 at 7:07

Pravin Junnarkar

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