times - Linux

Overview

The times command in Linux prints the accumulated user and system execution times for processes run from the shell. This command is useful for performance monitoring, allowing administrators and developers to measure the time taken by scripts or commands to execute in user and system space. It can be effectively used in scripting and process evaluation to ensure efficient resource usage.

Syntax

The basic usage of times command is very straightforward as it does not take any options or arguments:

times

When executed, times displays the cumulative CPU time in an easy-to-read format.

Options/Flags

The times command does not support any options or flags. It functions solely to report the CPU times.

Examples

Example 1: Basic Usage

To display the CPU times of the current shell session:

times

Output:

0m0.004s 0m0.005s
0m0.423s 0m0.029s

This indicates that the user CPU time was 0.004 seconds and system CPU time was 0.005 seconds for processes executed directly by the shell. The second row shows shell children’s user and system times.

Example 2: Using times in a Script

Measure how long a script takes to run:

#!/bin/bash
times
# Command that takes a while
sleep 3
times

This script will show CPU times before and after a sleep, helping you determine the time taken by the sleep command.

Common Issues

User Misunderstanding: Users might expect times to measure real, wall-clock time rather than CPU time. It’s important to understand it reports only the CPU time used by the current shell and its children.

Limited Detail: times provides a basic level of detail. For more advanced profiling, tools like time or profiling applications might be more suitable.

Integration

Integrate times with other commands using shell scripts to monitor and log performance over time:

#!/bin/bash
times > start_times.txt
# Execute commands
make build
times > end_times.txt
diff start_times.txt end_times.txt

This setup helps to capture the CPU times before and after a build process, allowing for a comparative analysis.

  • time: Unlike times, time can be used to measure the real, user, and system time taken by a command.
  • top and htop: These commands provide dynamic real-time views of running system’s processes.

For more in-depth analysis, consider exploring Linux performance monitoring tools like perf and strace.

For additional reading, consult the official Linux documentation at GNU.org.