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The append (a), insert (i), and change (c) commands provide editing functions that are commonly performed with an interactive editor, such as vi. You may find it strange to use these same commands to "enter" text using a noninteractive editor. The syntax of these commands is unusual for sed because they must be specified over multiple lines. The syntax follows:
append [line-address]a\ text insert [line-address]i\ text change [address]c\ text