paste

Merge lines of files, write to standard output lines consisting of sequentially corresponding lines of each given file, separated by a TAB character.

Syntax
      paste [options]... [file]...

Options
   -s
   --serial
        Paste the lines of one file at a time rather than one line from
        each file.

   -d DELIM-LIST
   --delimiters DELIM-LIST
        Consecutively use the characters in DELIM-LIST instead of TAB to
        separate merged lines.  When DELIM-LIST is exhausted, start again
        at its beginning.

Standard input is used for a file name of - or if no input files are given.

"The secret to success is to offend the greatest number of people" ~ George Bernard Shaw

Related linux commands:

csplit - Split a file into context-determined pieces.
cut - Divide a file into several parts.
fold - Wrap input lines to fit in specified width.
fmt - Reformat paragraph text.
join - Join lines on a common field.
split - Split a file into fixed-size pieces.
tail - Output the last part of files.