Concatenating 3 files into a single file

Shell Programming and Scripting
1

I have 3 files
File1

C1 C2 c3

File 2

C1 c2 c3

File 3

C1 c2 c3

Now i want to have
File1 as

C1 c2 c3 I

File2 as

C1 c2 c3 O

File3 as

c1 c2 c3 D

and these 3 files should be concatenated into a single file
how can it be done in unix script?

2

Please elucidate your data, for concatenate you can try paste command. Please use your delimeter as per your wish with -d option

paste  temp1.txt temp2.txt temp3.txt > temp4.txt
3

Try:

awk '{print $0,I}' I=I file1 I=O file2 I=D file3
4

The case of the data in your source files and expected output does not match. Is this intentional?