# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(\W|\s|\d|\w|\S)([7, 8][0-9]{10})//mg;t' <<< "84951234567
+74951234567
8-495-1-234-567
8 (8122) 56-56-56
8-911-1234567
8 (911) 12 345 67
8-911 12 345 67
8 (911) - 123 - 45 - 67
+ 7 999 123 4567
8 ( 999 ) 1234567
8 999 123 4567
// выше - правильные, ниже - неправильные:
02
84951234567 позвать люсю
849512345
849512345678
8 (409) 123-123-123
7900123467
5005005001
8888-8888-88
84951a234567
8495123456a
+1 234 5678901
+8 234 5678901
7 234 5678901
"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html