The xwininfo command is a utility for displaying information about windows on an X server. One of the information it displays is the depth of the window, which is the number of bits per pixel used to represent the color of the window. The depth of the root window, which is the background window of the X server, is the same as the color depth of the X server. To display the depth of the root window, one can use the command xwininfo -root and look for the line that says "depth of root window". Alternatively, one can use the command xdpyinfo, which displays information about the X server, and look for the line that says "depths of root window". References:
* xwininfo(1) - Linux man page
* xdpyinfo(1) - Linux man page
* [LPI Linux Certification/Configure the X Window System, Xorg and ...]

/usr/share/zoneinfo/

Explanation

/etc/cron.allow
Explanation:
The /etc/cron.allow file is a file that contains a list of users who are allowed to use the cron scheduling system.
The cron scheduling system is a way of running commands or scripts at specified times or intervals. Users can create their own cron jobs by using the crontab command, which edits a file called crontab that stores the user's scheduled tasks. However, not all usersmay have access to the crontab command or the cron system.
The access is controlled by two files: /etc/cron.allow and /etc/cron.deny. If the /etc/cron.allow file exists, then only the users listed in this file can use the crontab command and the cron system. The file should have one user name per line. If the /etc/cron.allow file does not exist, then the /etc/cron.deny file is checked. If this file exists, then the users listed in this file are denied access to the crontab command and the cron system. If neither file exists, then the access depends on the configuration of the cron daemon, which is the program that runs the cron jobs. By default, only the root user can use the cron system if no files exist. The root user can always use the cron system regardless of the existence or content of these files. To create or edit the
/etc/cron.allow file, the root user needs to use a text editor such as vi, nano, or emacs. For example, to allow the users alice and bob to use the cron system, the root user can use the following command:
sudo vi /etc/cron.allow
And then add the following lines to the file:
alice bob
And then save and exit the file. References:
* How cron.allow and cron.deny can be used to limit access to crontab for ...
* /etc/cron.allow - Linux Bash Shell Scripting Tutorial Wiki
* Linux / UNIX Restrict at / cron Usage To Authorized Users