Tail ending log rows and create new aggregated log file (rotate truncate shorten rotating log file)

These examples are very useful ways to quickly truncate and rotate your log files.  This is a very basic necessity for any server administration. If you do not rotate your logs, you will run out of disk space and one day your server will stop functioning properly.


Example for NGINX web server logs:

cp /log/nginx/error.log /data_local/tmp_nginx_log/nginx_error_`date +"%Y_%m_%d"`.log; truncate -s0 /log/nginx/error.log; kill -USR1 $( cat /var/run/nginx.pid )

kill -HUP $( cat /var/run/nginx.pid ) 

Example for APACHE web server logs:

tail -n 1000 error_php_apache.log > error_php_apache.log.tmp && mv -f error_php_apache.log.tmp error_php_apache.log && /etc/init.d/httpd graceful

or simpler way:

tail -n 1000 apache-error.log > apache-error.1.log && truncate -s 1M apache-error.log && service apache2 graceful

Get first 1000 lines from all *.log files and store them all in /log/all_logs

find /log -name "*.log" -type f | xargs tail -n 1000 2>&1 | tee /log/all_logs