nginx 日志默认文件名：
- access.log
- error.log
为了方便查询及归档，将日志文件设置为按照日期来分割，配置如下：
[root@nginx /usr/local/nginx/conf]#cat location.conf
map $time_iso8601 $logdate {
default 'date-not-found';
'~^(?<ymd>d{4}-d{2}-d{2})' $ymd;
}
map 指令是由 ngx_http_map_module 模块提供的，默认情况下安装 nginx 都会安装该模块。
上面这配置文件使用关键字 map 来定义一个变量 $logdate
如果 nginx 内置变量 $time_iso8601 通过正则能匹配到则 获取到 $logdate = $ymd 否则 $logdate = 'date-not-found'
接下来，在主配置文件中引用：
...
http {
include mime.types;
include location.conf;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log logs/access-$logdate.log main;
...
重载 nginx
[root@nginx /usr/local/nginx/conf]#nginx -t
nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful
[root@nginx /usr/local/nginx/conf]#nginx -s reload
注意：reload后日志文件不会马上生成，因为日期是通过 $time_iso8601 内置变量获取的。需要访问一下才会生成日志文件。
[root@nginx ~]#curl localhost
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
[root@nginx ~]#ls /usr/local/nginx/logs/
access.log error.log nginx.pid
当访问触发以后，如果还没有生成日期格式的日志文件，则检查下 nginx 运行用户及目录属主属组！
[root@nginx ~]#ll /usr/local/nginx/
total 4
drwx------ 2 root root 6 Nov 26 2016 client_body_temp
drwxr-xr-x 2 root root 4096 Jul 30 16:27 conf
drwx------ 2 root root 6 Nov 26 2016 fastcgi_temp
drwxr-xr-x 2 root root 40 Nov 26 2016 html
drwxr-xr-x 2 root root 87 Jul 30 16:20 logs
drwx------ 2 root root 6 Nov 26 2016 proxy_temp
drwxr-xr-x 2 root root 19 Nov 26 2016 sbin
drwx------ 2 root root 6 Nov 26 2016 scgi_temp
drwx------ 2 root root 6 Nov 26 2016 uwsgi_temp
[root@nginx ~]#ps -ef | egrep nginx
root 12916 1 0 16:20 ? 00:00:00 nginx: master process nginx
nginx 12933 12916 0 16:27 ? 00:00:00 nginx: worker process
root 12966 12879 0 17:47 pts/0 00:00:00 grep -E --color=auto nginx
当访问触发以后，如果还没有生成日期格式的日志文件，则检查下 nginx 运行用户及目录属主属组！
[root@nginx ~]#chown -R nginx:root /usr/local/nginx/
[root@nginx ~]#ll /usr/local/nginx/
total 4
drwx------ 2 nginx root 6 Nov 26 2016 client_body_temp
drwxr-xr-x 2 nginx root 4096 Jul 30 16:27 conf
drwx------ 2 nginx root 6 Nov 26 2016 fastcgi_temp
drwxr-xr-x 2 nginx root 40 Nov 26 2016 html
drwxr-xr-x 2 nginx root 87 Jul 30 16:20 logs
drwx------ 2 nginx root 6 Nov 26 2016 proxy_temp
drwxr-xr-x 2 nginx root 19 Nov 26 2016 sbin
drwx------ 2 nginx root 6 Nov 26 2016 scgi_temp
drwx------ 2 nginx root 6 Nov 26 2016 uwsgi_temp
# 再次访问，生成日志文件
[root@nginx ~]#curl localhost
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
[root@nginx ~]#ll /usr/local/nginx/logs/
total 12
-rw-r--r-- 1 nginx root 270 Jul 30 17:48 access-2020-07-30.log
-rw-r--r-- 1 nginx root 0 Nov 26 2016 access.log
-rw-r--r-- 1 nginx root 412 Jul 30 16:27 error.log
-rw-r--r-- 1 nginx root 6 Jul 30 16:20 nginx.pid