The (( command shifts
a designated block of lines of text one space to the left.
Optional Argument
n
specifies the number
of spaces that the designated block of lines of text shifts. The default
is one space. Follow the n argument
with a space. You can specify the numeric argument in the beginning
or ending line of the block command, or in both. If it is specified
in both, the first numeric argument is used.
Details
The (( command shifts
a designated block of lines of text one or more spaces to the left.
If the shift extends past the beginning of the current line, characters
are lost.
Comparisons
The ) and )) commands
shift text in the opposite direction from the ( and (( commands. The
<, <<, >, and >> commands are similar text-shift
commands, but they do not lose characters when shifting.