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GNU sed specify the end position when appending text

I want to do two things by sed when matching a pattern:

  1. Replace the pattern with a string
  2. Append another string after this line

Such as the original content in a text file is:

abc
123
edf

I want to replace 123 to XXX and append YYY after the line:

abc
XXX
YYY
edf

I tried to do this by sed '/123/{s/123/XXX;a\YYY\}', but it gave an error: Unmatched "{".

It seemed that command a treats all characters after it as text to append. So how can I make a know the end position of the text for append?

Solution

  • This might work for you (GNU sed):

    sed '/123/c\XXX\nYYY' file

    This uses the c command to change the line matched by the pattern.

    Or if you prefer to substitute and append:

    sed 's/123/XXX/;T;a\YYY' file

    Or:

    sed -e '/123/{s//XXX/;a\YYY' -e '}' file

    Or:

    sed $'/123/{s//XXX/;a\YYY\n}' file