join and paste command - join

Question

I have 2 files.
bash-3.2$ cat result2.txt
HOSTNAME=host4 2
HOSTNAME=host1 2
HOSTNAME=host6 1
HOSTNAME=host3 1
HOSTNAME=host2 1
bash-3.2$ cat result1.txt
HOSTNAME=host1 2
HOSTNAME=host2 1
bash-3.2$ cat result.txt
HOSTNAME=host1 2
HOSTNAME=host2 1
HOSTNAME=host3 1
bash-3.2$ cat result3.txt
HOSTNAME=host4 3
HOSTNAME=host1 4
HOSTNAME=host3 7
HOSTNAME=host2 8
HOSTNAME=host6 6
bash-3.2$ join -1 1 -2 1 -a 1 -a 1 result2.txt result1.txt
HOSTNAME=host4 2
HOSTNAME=host1 2
HOSTNAME=host6 1
HOSTNAME=host3 1
HOSTNAME=host2 1
I would like to join 2 files when the order and value of 1st column of both the files are not same.
I want the output to be
hostname result result1 result2 result3
HOSTNAME=host1 2 2 2 4
HOSTNAME=host2 1 1 1 8
HOSTNAME=host3 1 0 1 7
HOSTNAME=host4 0 0 2 3
HOSTNAME=host6 0 0 1 6
Even paste command is not working as it assumes the 1st column of both the files are same. Or is there any other command in bash that i can use for this output

Answer 1

Update: You changed the question significantly after I've answered it already. Now you say that you have 4 files instead of just 2.
However, the basic logic keeps the same, we just need to join again with the results of the previous join operation:
join -o auto -j1 -a1 -a2 -e0 \
<(join -o auto -j1 -a 1 -a 2 -e 0 \
<(join -o auto -j 1 -a 1 -a 2 -e 0 \
<(sort r1.txt) <(sort r0.txt)) <(sort r2.txt)) <(sort r3.txt)
Output:
HOSTNAME=host1 2 2 2 4
HOSTNAME=host2 1 1 1 8
HOSTNAME=host3 0 1 1 7
HOSTNAME=host4 0 0 2 3
HOSTNAME=host6 0 0 1 6
You are looking for the following command:
join -o '1.1 1.2 2.2' -j 1 -a 1 -a 2 -e 0 <(sort r2.txt) <(sort r1.txt)
Output:
HOSTNAME=host1 2 2
HOSTNAME=host2 1 1
HOSTNAME=host3 1 0
HOSTNAME=host4 2 0
HOSTNAME=host6 1 0
Explanation:
-j 1 is the same as -1 1 -2 1 (which you had). It means "join by field 1 in both files"
-a 1 -a 2 prints un-joinable lines from file1 and file2
-e 0 uses 0 as the default value for empty columns
<(sort file) is so called process substitution
-o '1.1 1.2 2.2' tells join that you want to output field 1 from file1 and field2 from file1 and file2. If one of the files is missing field2, a 0 will be used because of -e 0.

Answer 2

This is a solution on the first requirement, with just two files. For the solution on multiple files, check hek2mgl's answer!
What about using awk for this? It is just a matter of storing the data from the second file (result1.txt) in an array and then printing accordingly when reading the first one (result2.txt):
$ awk 'FNR==NR {data[$1]=$2; next} {print $0, ($1 in data) ? data[$1] : 0}' f2 f1
HOSTNAME=host4 2 0
HOSTNAME=host1 2 2
HOSTNAME=host6 1 0
HOSTNAME=host3 1 0
HOSTNAME=host2 1 1
If you need this to be sorted, pipe to sort: awk '...' f2 f1 | sort or say awk '...' f2 <(sort f1).
How does this work?
awk 'things' f2 f1
reads the file f2 and then the file f1.
FNR==NR {data[$1]=$2; next}
Since FNR stands for File Number of Record and NR for Number of Record, when reading the first file, these values match. This way, saying FNR==NR allows you to do something just when reading the first file. Here, it consists in storing the data in an array data[first field] = second field. Then, next triggers to skip the current line without doing anything else. You can read more about this technique in Idiomatic awk.
{print $0, ($1 in data) ? data[$1] : 0}
Now we are reading the second file. Here, we check if the first field is present in the array. If so, we print its corresponding value from the first file; otherwise, we just print a 0.