Passing variable into sshpass command inside a script for loop

Question

I am trying to create a script (test.sh) that logs on to another server and checks the disk usage of some different folders:

test.sh:

DIRS="dir_A dir_B dir_C"

for DIR in $DIRS
do
  sshpass -p user_password ssh -o StrictHostKeyChecking=no user_name@host 'cd /opt/app/$DIR;SIZE=$(du -s);echo "YVALUE="$SIZE > ../size_$DIR.txt'
done

However, the variable DIR never gets passed to the script. It is empty when I run the script. I have tried using {} around $DIR but still no success. What am I missing? Thanks for your help!

konsolebox · Accepted Answer · 2014-07-21 13:53:02Z

2

Basically, use double-quotes instead of single-quotes. You can still concatenate with single quotes if necessary:

sshpass -p user_password ssh -o StrictHostKeyChecking=no user_name@host 'cd /opt/app/'"$DIR"';SIZE=$(du -s);echo "YVALUE="$SIZE > ../size_'"$DIR".txt

I just noticed something: du -s produces an output of two columns so probably it's not being used the proper way yet. Perhaps something like SIZE=${SIZE%$'\t'*} is still needed.

Another way is to send the directory by input and let the other end read it:

sshpass -p user_password ssh -o StrictHostKeyChecking=no user_name@host 'read -r DIR; cd "/opt/app/$DIR"; SIZE=$(du -s); echo "YVALUE=$SIZE" > "../size_$DIR.txt"' <<< "$DIR"

This would be helpful if directories contain spaces or characters that may cause syntax errors. Using an array is also recommended for it:

DIRS=('DIR 1' 'DIR 2' 'DIR 3')
for DIR in "${DIRS[@]}"; do
    sshpass ...
done

edited Jul 21, 2014 at 13:53

answered Jul 21, 2014 at 13:38

konsolebox

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Comments

Andrew Stubbs · Accepted Answer · 2014-07-21 13:56:49Z

1

Wrapping a string in single quotes (') will stop any bash expansion taking place, you will need to use double quotes for $DIR to be evaluated, escaping any double quotes within the string that you want to send over SSH:

  sshpass -p user_password ssh -o StrictHostKeyChecking=no user_name@host "cd /opt/app/$DIR;SIZE=\$(du -s);echo \"YVALUE\"=$SIZE > ../size_$DIR.txt"

edited Jul 21, 2014 at 13:56

answered Jul 21, 2014 at 13:37

Andrew Stubbs

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1 Comment

user000001 Over a year ago

I would assume that the dollar in $(du -s) should also be escaped, otherwise he will be getting the local path size. Konsolebox's answer is better in my opinion anyway though, as it is less error prone.

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