Match a string that contains a newline using sed

Question

I have a string like this one:

    #
    pap

which basically translates to a \\t#\\n\\tpap and I want to replace it with:

Answer 1

This might work for you (GNU sed):

sed '/^\t#$/{n;/^\tpap$/{p;s//\tpython/}}' file

If a line contains only \t# print it, then if the next line contains only \tpap print it too, then replace that line with \tpython and print that.