unary operator expected in nfs mount shell script

Question

i just need safety process. nfs mount, data rsync, and shell ended.

rmv=`cat /proc/mounts | grep /mnt/nfs | cut -d: -f2 | awk '{print $2}'`
if [ $rmv != $@ ]; then
 echo "not mounted"
 else if umount /mnt/nfs > /dev/null 2>&1 || /bin/false; then
 umount successed
  else
  device is busy"
  fi
fi

is working but...

'[' /mnt/nfs '!=' ']'
[: /mnt/nfs: unary operator expected

i got using "$@" i think i was wrong expression. need other ways

Answer 1

There are actually quite a few flaws in your initial script, and some unnecessary use of code/commands.... does this do what you want? Note - it's untested, but I think it's syntactically correct.

rmv=$(awk -F"[: ]+" '/\/mnt\/nfs/{print $2}' /proc/mounts)
if [ $rmv == "" ]; then
  echo "not mounted"
else 
  if umount /mnt/nfs > /dev/null 2>&1 ; then
    echo "umount succeeded"
  else
    echo "device is busy"
  fi
fi