Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
How to change the nginx log format?
Answer:
Firstly, you need to define a valid log format for nginx, e.g.
log_format foo '$remote_addr - $remote_user [$time_local] '
'"$request" $status $bytes_sent '
'"$http_referer" "$http_user_agent"';
Then, you need to link that format with your log file:
access_log /var/logs/nginx-test-access.log foo;
Display the top 10 processes used up the most of the memory
Answer:
The following command display the most top 10 processes used up the most of the memory in your Linux system.
Example:
# ps aux | sort -nk +4 | tail
www-data 27972 0.0 2.8 253896 14916 ? S 13:10 0:00 /usr/sbin/apache2 -k start
www-data 27725 0.0 2.9 254028 15572 ? S 12:52 0:00 /usr/sbin/apache2 -k start
www-data 27912 0.0 2.9 253896 15660 ? S 13:06 0:00 /usr/sbin/apache2 -k start
www-data 27946 0.0 2.9 253764 15492 ? S 13:08 0:00 /usr/sbin/apache2 -k start
root 2710 0.0 3.1 252996 16444 ? Ss Dec08 1:20 /usr/sbin/apache2 -k start
www-data 27885 0.0 3.4 253508 18152 ? S 13:05 0:00 /usr/sbin/apache2 -k start
www-data 27892 0.1 6.7 261748 35472 ? S 13:06 0:00 /usr/sbin/apache2 -k start
www-data 27975 0.3 7.0 263036 37128 ? S 13:10 0:00 /usr/sbin/apache2 -k start
www-data 27964 0.7 8.2 268532 43452 ? S 13:09 0:00 /usr/sbin/apache2 -k start
mysql 2480 0.4 8.7 223920 46096 ? Sl Dec08 21:07 /usr/sbin/mysqld
Since the apache2 was configured to run in the prefork mode, so you see multiple apache processes there.
Check the number of active Apache connection
Answer:
When your Apache server is overloaded, you might want to check how many active connections are there.
# netstat -anpt|grep apache2 |grep ESTABLISHED
Replace apache2 with httpd if you are using CentOS/Fedora/RHEL.
Enable gzip compression in Nginx
Answer:
Enabling gzip compression for text based output such as HTML can greatly improve the response of user.
If you are using nginx, it is easy by adding the following lines in your nginx.conf
gzip on;
gzip_min_length 1000;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain text/html text/css application/json application/x-javascript text/javascript text/xml application/xml;
Check which Apache modules are loaded
Answer:
To check which Apache modules are loaded, in RHEL/Fedora/CentOS, type
# httpd -M
In Debian/Ubuntu
# sudo apache2ctl -M
