Чтобы любой из упомянутых примеров был действительно значимым, вам нужно будет убрать даты из каждой строки. Предполагая, что строка в вашем журнале выглядит так:
[Wed Oct 24 10:17:17 2012] [notice] caught SIGTERM, shutting down
тогда вы могли бы сделать что-то вроде:
tail -n 5000 /var/log/apache2/error_log |\
cut -d] -f2- |\
awk '{a[$0]++} END \
{for (i in a) {printf "%s\t%s\n", a[i], i;} }' |\
sort -n
Это даст результат, похожий на:
13 [error] [client 127.0.0.1] column: address_phonerename: phone, referer: http://l27/symfony/web/varelager/adminpanel
13 [error] [client 127.0.0.1] column: address_streetrename: street, referer: http://l27/symfony/web/varelager/adminpanel
13 [error] [client 127.0.0.1] column: address_zipcoderename: zipcode, referer: http://l27/symfony/web/varelager/adminpanel
13 [error] [client 127.0.0.1] column: user_activerename: active, referer: http://l27/symfony/web/varelager/adminpanel
13 [error] [client 127.0.0.1] column: user_idrename: id, referer: http://l27/symfony/web/varelager/adminpanel
13 [error] [client 127.0.0.1] column: user_nameFirstrename: nameFirst, referer: http://l27/symfony/web/varelager/adminpanel
13 [error] [client 127.0.0.1] column: user_nameLastrename: nameLast, referer: http://l27/symfony/web/varelager/adminpanel
13 [error] [client 127.0.0.1] column: user_usernamerename: username, referer: http://l27/symfony/web/varelager/adminpanel
56 [error] [client 127.0.0.1] PHP Parse error: syntax error, unexpected '}' in /var/www/localhost/htdocs/tmp/php/log/index.php on line 6, referer: http://l27/symfony/web/varelager/adminpanel
56 [error] [client 127.0.0.1] PHP Parse error: syntax error, unexpected ';' in /var/www/localhost/htdocs/tmp/php/log/index.php on line 9, referer: http://l27/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: address_cityrename: city, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: address_idrename: address_id, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: address_namerename: addr_name, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: address_streetrename: street, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: address_zipcoderename: zipcode, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: user_activerename: active, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: user_idrename: id, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: user_nameFirstrename: nameFirst, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: user_nameLastrename: nameLast, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
300 [error] [client 192.168.0.105] column: user_usernamerename: username, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
301 [error] [client 192.168.0.105] column: address_commentrename: comment, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
301 [error] [client 192.168.0.105] column: address_countryrename: country, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
301 [error] [client 192.168.0.105] column: address_emailrename: email, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
301 [error] [client 192.168.0.105] column: address_phonerename: phone, referer: http://192.168.0.100/symfony/web/varelager/adminpanel
451 [error] [client 192.168.0.103] File does not exist: /var/www/localhost/htdocs/WebServices