Linux and Unix paste command
The paste command displays the corresponding lines of multiple files side-by-side.
paste [OPTION]... [FILE]...
paste writes lines consisting of the sequentially corresponding lines from each FILE, separated by tabs, to the standard output. With no FILE, or when FILE is a dash ("-"), paste reads from standard input.
|-d, --delimiters=LIST||reuse characters from LIST instead of tabs.|
|-s, --serial||paste one file at a time instead of in parallel.|
|--help||Display a help message, and exit.|
|--version||Display version information, and exit.|
paste file1.txt file2.txt
This command would display the contents of file1.txt and file2.txt, side-by-side, with the corresponding lines of each file separated by a tab.