There are many files that crawlers expect to find in well-known locations on websites, one such file is ads.txt. While you might not have paid advertisements, crawlers may still look for a copy of this file leading to HTTP 404 errors in your logs. To prevent the error and show that you should have no advertisements leading there you can add the file with placeholder values as follows:
In the root of your website, create a new file with the name ads.txt.
#ads.txt - no DIRECT or RESELLER
www.example.com, placeholder, DIRECT, placeholder
NOTE: If you ever do use an advertiser, they will generally inform you as to changes to make to this file.
If you support code for multiple java application servers, you might eventually encounter a file named:
JBoss uses this file to control the path of the web application, whereas Tomcat generally uses the filename of the WAR itself.
Usually, the contents are pretty sparse, you might consider adding one to your projects should you ever wish to deploy them on JBoss:
NOTE: There are several other attributes that can find their way into this file for JBoss, notably security configuration, like JAAS.
WARNING: Unfortunately, I’ve tried to add a simple
DOCTYPE jboss-web and XML preamble to this, file to make it validate, but the server (JBoss 5.1.x) fails to recognize them.
If you’ve been following my posts for a while, you will have also noticed the use of the
sudo command in a lot of the Unix/Linux configuration and setup instructions. This is because of the security model used by these operating systems. Users generally have limited access, and only the ‘root’ or admin accounts has greater access. A common convention is to use the sudo command to allow for temporary (usually 5 minutes at a time) permission to make changes, using escalated rights for an existing non root user.
It’s often best to think of “sudo” as “mother may I”, as the server administrator can give users access to some (but not all) commands.
Permissions are stored in a file that can be edited in a variety of manners (do so carefully):
To give an existing user permission to use sudo…
sudo adduser USERNAME sudo