Compare two arrays

Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Compare two arrays
# 1  
Old 01-29-2013
Compare two arrays


I am trying to compare two lists that are held in two variables so I believe I need to access the array elements to compare these. I am using ksh 88 and the code I have tried is below:

for file in ${origfilelist}
        if [[ "${file}" != $failfiles[@] ]]
                print -- "File ${file} not found "
                print -- "File ${file} found"

Unfortunately all are being flagged up as 'not found' when I know there are some of the same filenames in both variables.


Last edited by frodo61; 01-29-2013 at 08:59 AM..
# 2  
Old 01-29-2013
For lists you could do something like:

A="1 2 3 4"
B="5 6 2 7"

for a in $A; do
        for b in $B; do
                (( $a == $b )) && print $a

exit 0

For arrays you'll have to declare them with set -A ..... and cycle through their elements by incrementing the index. Though it would be most likely 2 loops in each other like the example above.

Here an example with an array without incrementing the indexes and comparing strings instead of numbers.
But when there is no need for indexes, maybe a list will be sufficient instead of arrays. But when having spaces in file names it might be easier to use them as array elements than in a list (depending how the separator IFS is defined and used in the list of course).


set -A ARR1 1 2 3 4
set -A ARR2 5 6 2 7

for a in ${ARR1[*]}; do
        for b in ${ARR2[*]}; do
                [[ "$a" = "$b" ]] && print $a

exit 0

Last edited by zaxxon; 01-29-2013 at 09:45 AM.. Reason: no automatic update, merging posts
This User Gave Thanks to zaxxon For This Post:
# 3  
Old 01-30-2013
Thanks. The nested for loop works but if I want to output files that arent found as well I get repeated messages due to not matching to any of the array elements, how could I only output the filenames that arent found just once? I guess I could put them into another variable and then use the uniq command maybe?

for orig in ${origfilelist}
        for fail in ${failfiles}
                if [[ ${orig} == ${fail} ]]
                print -- "File ${orig} found "
print -- "File ${orig} not found"


p.s I though all variables were arrays?

---------- Post updated 30-01-13 at 09:17 AM ---------- Previous update was 29-01-13 at 01:11 PM ----------

Although I still would like the answer to the previous question I also need to know how to output the array elements onto different lines in a text file?

IFS solutions dont seem to be working.

OLDIFS="$IFS"; IFS=$'\n'
echo "${failagain[*]}" >>"${reloadfiles}"/results.txt

I have now been able to output to single lines by using another for loop.

for i in ${failagain[*]}
echo $i >>"${reloadfiles}"/results.txt

Last edited by frodo61; 01-30-2013 at 07:10 AM..
# 4  
Old 02-03-2013
Here is an example how you could cycle and compare array elements (example with integers) and print only those from array 1, which are not in array 2:
$ cat ./mach.ksh

set -A ARR1 4 1 3 2
set -A ARR2 5 6 2 7 4 8


for a in ${ARR1[*]}; do
        set -A HITS
        for b in ${ARR2[*]}; do
                (( $a != $b )) && \
                HITS[$COUNT]=$a && \
                let COUNT+=1
        (( ${#HITS[*]} != $MAX )) && \
        print ${HITS[0]}
        unset HITS

exit 0

$ ./mach.ksh

Somehow there is a blank line at the end. Didn't find where it comes from Smilie

Maybe other people have more efficient algorithm to do this which would be interessting for me too.

If you have 2 files with the lists of files you might want to compare, a grep -f file1 file2 or grep -vf file1 file2 might be more efficient than my example.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Using Diff to compare 2 arrays

I have two arrays and they look like this: array=(`cat /local/mnt/*sys/*includes|grep -v NEW`) array2=(`cat /tmp/*sys.z |grep -v NEW`) I am trying to compare them but I need to use the diff -u command. I am not sure how to do this. I cannot just do diff -u ${array} ${array2} I cannot... (4 Replies)
Discussion started by: newbie2010
4 Replies

2. Shell Programming and Scripting

Bash arrays that compare ip addresses.

I've been trying to have an array of ip addresses go through a loop one at a time. Then compare if the current element is in another array of ip addresses. I've traced my error with /bin/bash -x + for c in '"${ip}"' ./netk5: line 65: (17 Replies)
Discussion started by: Azrael
17 Replies

3. Shell Programming and Scripting

perl: compare two arrays

Hi friends, I want to compare two arrays and find matched one using perl? Also, I want to delete unmatched one. Plz suggest me solution (1 Reply)
Discussion started by: Renesh
1 Replies

4. Shell Programming and Scripting

Perl Compare 2 Arrays

Hello, Consider the following 2 arrays: Array1 = qw(Fa0/0 Fa0/1 Fa0/2 Fa0/3); Array1 = qw(Fa0/1 Fa0/2 Fa0/3 Fa0/4); I want to compare the following 2 arrays as follows: Take specific action when elements of Array1 that doesn't exist in Array2 (in my example: Fa0/0). Take another... (4 Replies)
Discussion started by: ahmed_zaher
4 Replies

5. Shell Programming and Scripting

Compare arrays (perl)

Hi, my first post here! Description of my problem: I have one txt-file with six rows and each row contains seven numbers seperated with whitespaces. I want to: Compare one array with seven numbers with each row of numbers in the txt-file. I have managed to compare one array with... (6 Replies)
Discussion started by: mjoh
6 Replies

6. Shell Programming and Scripting

compare 2 arrays in perl

Hi Im supposed to compare lines in a file : KB0005 1019 T IFVATVPVI 0.691 PKC YES KB0005 1036 T YFLQTSQQL 0.785 PKC YES KB0005 1037 S FLQTSQQLK 0.585 DNAPK YES KB0005 1045 S KQLESEGRS 0.669 PKC YES KB0005 1045 S KQLESEGRS 0.880 unsp YES KB204320 1019 T IFVATVPVI 0.699 PKC YES ... (7 Replies)
Discussion started by: karla
7 Replies

7. Shell Programming and Scripting

Compare arrays in perl

Hello, Let's say that we have the two following arrays @array1= @array2= Is there any easy way to compare these two arrays and print the values that exist in array1 and not in array2 and the values that exist in array2 and not in array1? Regards, Chriss_58 (3 Replies)
Discussion started by: chriss_58
3 Replies

8. Shell Programming and Scripting

compare/match arrays

Hi there all, I am having a question. Is it posible to compare elements of 2 different arrays? For example I got Array 1 | Array 2 123_abc | 123_bcd 123_bcd | 234_bcd 234_abc | 567_abc 234_bcd | 123_abc than the match is 123_abc & 234_bcd and non of the others. So... (3 Replies)
Discussion started by: draco
3 Replies

9. Shell Programming and Scripting

Perl - Compare 2 Arrays

Hi all, I have the following script where the contents of file1 and file2 would be something like this: file1: 56790,0,0,100998765 89756,0,0,100567876 867645,1,3,678777654 file2: 56790,0,0,100998765 65776,0,0,4766457890 +5896,0,0,675489876 What I then want to do is check if... (4 Replies)
Discussion started by: Donkey25
4 Replies

10. Shell Programming and Scripting

Compare two arrays in sh or compare two fields

I want a soultion to compare two arrays in sh with an easy way.I want a solution to synchrose users between different AIX servers where no NIS is available. All users are meant to be same on all 10 servers. So the approach is to consider first server as master user repository and whatever the users... (0 Replies)
Discussion started by: rijeshpp
0 Replies
Login or Register to Ask a Question

Featured Tech Videos