资料来源 : Free On-Line Dictionary of Computing

internal field separators
     
         ($IFS) A predefined {environment variable}
        in the {Unix} {Bourne shell} whose default value is the
        three-character string containing {space}, {tab} and {line
        feed}.  Any string of one or more of these characters
        separates the command and each of its arguments in a command
        line.
     
        $IFS also tells the shell's built-in read command where to
        split an input line when reading into multiple variables.
        E.g. setting IFS=: would be appropriate for reading a file
        with ':'-separated fields, such as /etc/passwd.
     
        (1999-04-07)