Time Command in Bash Script

In the world of Bash scripting, understanding how time your command take to run can be invaluable. Whether you’re optimizing your code or simply curious about performance, the time command is a powerful tool at your disposal.

Let’s delve into its capabilities and how you can leverage it effectively.

Introducing the Time Command

The time command is a built-in command in Bash that provides valuable insights into the execution time of other commands. It measures the real time, user CPU time, and system CPU time taken by a command to complete.

Real, User, and Sys Time

When you run a command with time, it provides three key metrics:

  • Real Time: This is the total elapsed time from the start to the end of the command’s execution. It’s akin to timing the command with a stopwatch in real life.
  • User Time: This represents the amount of CPU time spent executing the command’s instructions within the user space.
  • Sys Time: This indicates the CPU time spent by the kernel on behalf of the command, handling system calls and other kernel-level operations.

Understanding the Metrics

  • Real Time: This metric is often the most relevant for users. It gives a clear indication of how long the command took to execute in real-world terms.
  • User and Sys Time: These metrics provide insights into the computational resources consumed by the command. They can be useful for identifying bottlenecks and optimizing performance.

Practical Usage

To use the time command, simply prepend it to the command you want to measure. For example:

This command will list the detail of current process running on the system (ps -l) and report the execution time using time.

Interpreting the Output

When you run a command with time, the output will include the real, user, and sys time metrics. Understanding these metrics can help you diagnose performance issues and fine-tune your scripts for optimal efficiency.


The time command is a valuable tool for monitoring command performance in Bash. By understanding the real, user, and sys time metrics it provides, you can gain insights into your scripts’ efficiency and identify areas for improvement. Incorporate time into your Bash workflow to take your scripting skills to the next level.