Unix time a program

The computer might still be running an operating system and some background tasks, but no GUI or any other application software. This will give you the best possible testing environment, so using System Time is the right choice. In the following sections, we will explore the most commonly used techniques for quantifying time-based optimization. The simplest and most intuitive way to measure time is to use a stopwatch manually from the moment you start a program.

Assuming you manage to start the stopwatch and the program at the same time, the option requires the program to print a certain warning at the end of execution or at the end of a subroutine. This technique is not the most optimal, since on average a human takes from 0. A faster and more automated alternative to the manual stopwatch is the time utility, which is very easy to use and requires no special settings.

It is sufficient to use the following syntax time. Together with the result of the program, the time utility prints three different types of time:. The reason for the difference between User Time and System Time is the result of internal mechanisms on how the execution of a process works. Generally speaking and in a very simplistic way, we can identify two separate parts within an operating system: a user part and a supervisor part kernel mode with higher privileges than the user.

Most of the instructions of a process are executable in user mode and do not require the necessary privileges. This is also called Principe of Least Privilege and is very important: in this way, the user does not have maximum privileges and is not free to do what it wants.

To execute a program correctly, it is essential that all subparts are synchronized at the right time. Physically, a computer is composed of electrical signals and if they delay or overlap, the system may not respond correctly. It is generated by a mineral often Quartz inside the CPU and the frequency of the signal i.

If the electronic devices respond in the rising edge i. This being the case, it is intuitive to think that if you have the amount of clock cycles performed in a second and know the difference of clock cycles calculated between two instants, you can convert it to seconds. Robel Sharma Robel Sharma 1 1 gold badge 11 11 silver badges 26 26 bronze badges. No need to use -lphtread or -o tags.

Just need to use the time command, which the accepted answer explains better. It was an example. That is my perform. Not the point when program executes, but the duration of program executing. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog.

Podcast Making Agile work for data science. Stack Gives Back Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Linked See more linked questions. The solution using times writes to stdout. The other solutions involve calling external programs like date or perf which is not efficient. If you are fine with any of these, use it. Longer variant that keeps original stdout and stderr separate of each other:.

You can even fake a floating point addition in bash without calling bc which would be much slower:. Here's a variation of Alex's answer. I only care about minutes and seconds, but I also wanted it formatted differently. So I did this:. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more.

How to get execution time of a script effectively? Ask Question. Asked 9 years, 2 months ago. Active 15 days ago. Viewed k times. I would like to display the completion time of a script.

What I currently do is -! Improve this question. I think the current accepted answer is not really enough because of temporal fluctuations. Also related: stackoverflow. There is a command that you can run and then it times all unix commands automatically, forgot howto enable? Add a comment.

Active Oldest Votes. Just use time when you call the script: time yourscript. Improve this answer. Trudbert Trudbert 7, 1 1 gold badge 12 12 silver badges 5 5 bronze badges. This outputs three times: real , user and sys. For the meanings of these, see here. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast Making Agile work for data science. Stack Gives Back Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Linked