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# 1  
Old 09-11-2019
Compare bash arrays issue

Hello everyone,
I need help comparing 2 arrays. the first array is static; the second array is not ..

Code:
array1=( "macOS Mojave" "iTunes" )
cd /Volumes
array2=( * )

# output of array2
Code:
macOS Mojave
iTunes
Mac me

The problem occurs when I compare the arrays with the following code -

Code:
 DIFF=`echo "${array1[@]}" "${array2[@]}" | tr ' ' '\n' | sort | uniq -u`

for x in "${DIFF[@]}"
        do
                echo -e "$x"
        done

# wrong result
Code:
Mac
me

# desired result
Code:
Mac me

I'm sending the output via email and it still splits up "Mac" "me" on separate lines. How could I keep the DIFF array intact? Not separating the words when I do the compare?

Last edited by Scrutinizer; 09-12-2019 at 12:16 AM.. Reason: code tags
# 2  
Old 09-12-2019
Quote:
Originally Posted by trexthurman
[..]How could I keep the DIFF array intact? Not separating the words when I do the compare?
Indeed, the operation should be line based, rather than word based, since file names can have spaces in them.

Compare:
Code:
echo "${array1[@]}" "${array2[@]}" | tr ' ' '\n' | sort | uniq -u

with:
Code:
printf "%s\n" "${array1[@]}" "${array2[@]}" | sort | uniq -u



--
Note: File names could even have newlines in them, but it is rare so let's leave that for now......

Last edited by Scrutinizer; 09-12-2019 at 04:12 AM..
This User Gave Thanks to Scrutinizer For This Post:
# 3  
Old 09-12-2019
$DIFF in not an array but a scalar variable.
Try also
Code:
IFS=$'\n'
echo "${array1[*]}"$'\n'"${array2[*]}" | sort | uniq -u
Mac me

Don't forget to reset IFS to your default value.
This User Gave Thanks to RudiC For This Post:
# 4  
Old 09-12-2019
Your suggestions work for outputting to standard output but as I was testing the email portion, if there are 2 entries as differences - it treated them as 1 element in the array as oppose to 2 elements. I was hoping to have both differences in the array as its own element.

Code:
length=${#DIFF[@]}
for (( i=0; i<${length}; i++ ));
do
echo ${DIFF[i]}
done

# wrong result
Code:
DIFF[0] Mac me 
Windows
DIFF[0] Mac me Windows

# Desired result
Code:
DIFF[0] Mac me
DIFF[1] Windows


Last edited by Scrutinizer; 09-12-2019 at 02:40 PM.. Reason: code tags
# 5  
Old 09-12-2019
Again: DIFF is a scalar NOT an array the way you create / populate it. There is NO ${DIFF[1]}!


Wouldn't it be better to show the big picture of your problem, so a tailored solution can be found? What are you after, in the end?
# 6  
Old 09-12-2019
Here is the code I'm working on. After comparing both arrays, if multiple differences are detected between arr1 and arr2. I should be able to send an email for each difference found. Below, looks like I'm still treating the scalar as an array? Is there a way to make the scalar into array after comparing so I can access the elements individually?

Code:
arr1=( "macOS Mojave" "iTunes" )
cd /Volumes
arr2=( * )

IFS=$'\n'
DIFF=`echo "${arr1[*]}"$'\n'"${arr2[*]}" | sort | uniq -u`
VOLCOUNT=`printf "%s\n" "${arr1[@]}" "${arr2[@]}" | sort | uniq -u | wc -l`
if [ "$VOLCOUNT" -gt "$COUNT" ]; then
        for x in "${DIFF[@]}"
        do
                echo -e "To: ${TO}\nSubject: Alert: ${SUBJECT}$x \n\n$SIGN" | $MAIL -a gmail ${TO}
        done
else
        >/dev/null 2>&1
fi
unset $IFS
exit 0


Last edited by Scrutinizer; 09-12-2019 at 02:41 PM.. Reason: code tags
# 7  
Old 09-12-2019
Quote:
Originally Posted by trexthurman
...
Is there a way to make the scalar into array after comparing so I can access the elements individually?
Yes. You did it twice with arr1 and arr2. It can vary from shell to shell, so it's best to always post your OS and shell.



Quote:
unset $IFS
Don't unset IFS - reset it to its former (saved!?) value.

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