How can i union two files that each of them contain text to one new file in unix shell scripting or in awk scripting language?
What do you mean by "union"? Do you just want the contents of both files together in one file? If so, just use cat.
cat file1 file2 > file3
Do you want a file containing only the lines that are the same in both? Use fgrep.
fgrep file1 file2 > file3