How to grep in tail in several files

Question

I need to tail several files, and most info from them i removing (using grep). Now mine output dirty with file names. How i can remove them?

Short to problem: $ tail -F /log/rest_server*.log | egrep -v ' INFO (<some regext>)'

return:

==> /log/rest_server_dbs0.log <==

==> /log/rest_server_dbs1.log <==
<some useful data1>

==> /log/rest_server_dbs0.log <==

==> /log/rest_server_dbs1.log <==
<some useful data2>

==> /log/rest_server_dbs0.log <==

==> /log/rest_server_dbs1.log <==

==> /log/rest_server_dbs0.log <==

==> /log/rest_server_dbs1.log <==

==> /log/rest_server_dbm0.log <==
<some useful data3>

==> /log/rest_server_dbs1.log <==

==> /log/rest_server_dbs0.log <==

==> /log/rest_server_dbs1.log <==

==> /log/rest_server_dbs0.log <==

==> /log/rest_server_dbs1.log <==

==> /log/rest_server_dbs0.log <==

==> /log/rest_server_dbs1.log <==

==> /log/rest_server_dbm0.log <==
<some useful data4>

==> /log/rest_server_dbs1.log <==

How I can remove this file names and black lines, if there is no data?

to make result

==> /log/rest_server_dbs1.log <==
<some useful data1>
<some useful data2>

==> /log/rest_server_dbm0.log <==
<some useful data3>
<some useful data4>

Answer 1

You can use the following commands instead:

$ tail -F /log/rest_server*.log | sed -e "/^==>/d;/^$/d" | egrep -v ' INFO (<some regext>)'

The sed command removes the lines that start with "==>" and those that are empty;