Knowledge base dedicated to Linux and applied mathematics.

Home > Linux > Tip of the day > Time a task: time

Time a task: time

All the versions of this article: <English> <français>

It proves sometimes useful to know the execution time of a task. The time command makes it possible to determine the duration of a process, it uses the clock system, so it depends on your processor and on its request: in other words, if you watch a movie and you compile a C++ program, the time compilation will last longer that if you compile it without watching the movie.

To time a task, we use the time command plus the task. Here, we want to list (ls -al) the whole current directory recursively(R), i.e. we also consider subdirectories.

nadir@ipowerht:~ $ time ls -aRl

real    0m1.541s
user    0m0.047s
sys     0m0.046s

 real corresponds to the real time of the task. .
 user corresponds to the user time, i.e. the CPU time used by the user’s program
 sys defines time system, that corresponds to the time used by the system to manage the execution of the task.

Consequently, we easily determine time CPU of the task, I recall you that time CPU is defines as follows: CPU = user time + sys time.
Then do not waste time, and test this command!

Also in this section

  1. Crontab : Scheduling Tasks
  2. Archiving and compressing data files tar
  3. Check/find version of numpy i’m using
  4. Comment changer son adresse MAC sous Linux
  5. Download music and videos .mp3, .wma, .avi, .mpg , divx with google
  6. Find list of options that python was compiled with
  7. Find out biggest cpu/memory consuming processes with ps command
  8. Generating a self-signed certificate using OpenSSL with Linux CentOs/RedHat for Apache/httpd
  9. GNU compilation for MIC architecture KNL Knights Landing
  10. Got permission denied while trying to connect to the Docker daemon socket
  11. How to change the MAC address on Linux
  12. How to Convert Text File From ISO-8859-15 to UTF-8 Encoding
  13. How to diff remote files using ssh ?
  14. How to encrypt/decrypt a file or directory in Linux?
  15. How to make a denial of a service with fork functions in BASH ?
  16. How to setup SSH timeout in shell script ?
  17. Intel compilation for MIC architecture KNL Knights Landing
  18. Linux How to connect to Windows with remote desktop RDP in CentOS 7 / RedHat 7
  19. Linux How to delete or remove printer from command line
  20. phpMyAdmin: Search and Replace in MySQL database
  21. Speedup GNU make build and compilation process
  22. SVN — Branch, Branching subversion howto
  23. SVN — How to ignore file or directory in subversion?
  24. Time a task: time