Break for loop if variable is false - unix

Question

Trying to break a for loop if the variable $DEVP doesn't exist.
nme=(Y6T1 Y6-T1 Y6.T1 Yr6T1 Yr6-T1 Yr6.T1 Yr6Term1)
DEVP=(/dev/disk2 /dev/disk3 /dev/disk4 /dev/disk5 /dev/disk6 /dev/disk7 /dev/disk8)
for ((i = 0; i < 7; i++)) ; do
if [ ${nme[i]} ${DEVP[i]} = 0 ] ; then
diskutil eraseDisk FAT32 ${nme[i]} ${DEVP[i]}
else
echo “Formatted USBs” ; break
fi
done

Answer 1

The break works fine
for ((i = 0; i < 7; i++)) ; do
if [ $i -lt 3 ] ; then
echo $i
else
echo “Formatted USBs” ; break
fi
done
Output is:
0
1
2
“Formatted USBs”
, however I'm not sure regarding your if statement, you should probably use -z.
if [ -z ${DEVP[i]} ] ; then
Have a look here

Answer 2

Your comparison looks like you expect the two strings to contain the single number zero. They never will. If they are empty, they will contain the empty string. (But even then having two string arguments to the left of the comparison operator is a syntax error.)
Anyway, if the actual problem you are trying to solve is that you don't know how many elements these arrays contain, just ask.
for((i=0; i<${#DEVP[#]}; ++i)); do
Of course, if the arrays contain a different number of arguments, you could still end up in a situation where ${nme[i]} is undefined.
${nme[i]+:} break
This is rather obscure -- it will expand to the empty string before break (and thus break out of the loop) if the value is unset; if it's set, this is just a : noop.

Answer 3

First repair the syntax: Put things in quotes in the if statement.
EDIT: I thought you needed to refer to the var i with $i, but #tripleee showed me, that this is optional in bash arrays. I removed the extra $ characters.
nme=(Y6T1 Y6-T1 Y6.T1 Yr6T1 Yr6-T1 Yr6.T1 Yr6Term1)
DEVP=(/dev/disk2 /dev/disk3 /dev/disk4 /dev/disk5 /dev/disk6 /dev/disk7 /dev/disk8)
for ((i = 0; i < 7; i++)) ; do
if [ "${nme[i]} ${DEVP[i]}" = 0 ] ; then
echo "diskutil eraseDisk FAT32 ${nme[i]} ${DEVP[i]}"
else
echo “Formatted USBs” ; break
fi
done
If you want to check the vars being empty, introduce an error by looping until 8.
I have put an echo in front of the diskutil line, so you can test without doing something you do not want.
for ((i = 0; i < 8; i++)) ; do
if [ -z "${nme[i]}" ]; then
echo "loop $i: \${nme[i]} is empty";
break;
fi
if [ -z "${DEVP[i]}" ]; then
echo "loop $i: \${DEVP[i]} is empty";
break;
fi
echo "diskutil eraseDisk FAT32 ${nme[i]} ${DEVP[i]}"
done