qstail command not found

Introduction

When you run more command in linux terminal / console, you get the following error message

qstail: command not found

or when using sudo you get the following error message

sudo: qstail: command not found

Solutions to qstail: command not found

How To Fix qstail: command not found in Ubuntu / Debian / Kali Linux / Raspbian

In Ubuntu qstail is provided by libapache2-mod-qos package.

libapache2-mod-qos is:

This is a quality of service module (QoS) for the Apache web server implementing control mechanisms that can provide different priority to different HTTP requests.

It may be used to determine which requests should be served and which shouldn’t in order to avoid resource oversubscription. The module collects different attributes such as the request URL, HTTP request and response headers, the IP source address, the HTTP response code, history data (user session and on per source IP address basis), the number of concurrent requests to the server (total or requests having similar attributes), the number of concurrent TCP connections (total or from a single source IP), and so forth.

Counteractive measures to enforce the defined rules are: request blocking, dynamic timeout adjustment, request delay, response throttling, and dropping of TCP connections.

To fix this problem, we can install more using the command below.

sudo apt-get -y install libapache2-mod-qos

This command might take some time to finish depending on your machine internet connection.

You can also use apt command to install libapache2-mod-qos.

sudo apt -y install libapache2-mod-qos

Or if you have aptitude installed you can use the following command.

sudo aptitude install libapache2-mod-qos

Summary

In this tutorial we learn how to fix qstail command not found error in Ubuntu / Debian / Kali Linux or Raspbian distribution.