delete lines before match sed code example

Example 1: sed delete line before match

Use d option at the end of sed command string for deleting line of matches.
tac | sed -i "" "s/matching_pattern/I+1 d" file.txt | tac #

Example 2: delete strings after match to eol using sed command

$ cat file | awk -F '\\.com' '{print $1".com"}'
google.com
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isuckatunix.com