尝试一下:

# output: example.com/test
rewrite ^/([A-Za-z0-9_]+)$ /page.php?username=$1;

更新:

{1,35}此表达式允许输入1到35个字符

{1,35} This expression allow from 1 to 35 character

{20}必须精确到20个字符

{20} That have to exactly 20 character

+说出至少1个字符

正确的完全重写规则:

# output: example.com/test
rewrite "^/([A-Za-z0-9_]{1,35})$" /page.php?username=$1;