Calculating the execution time for a command

While testing an application's efficiency or comparing different algorithms to solve a given problem, the execution time taken is very critical. A good algorithm should execute in a minimum amount of time. Let's see how to calculate the execution time.

How to do it...

1. To measure the execution time, just prefix time to the command you want to run.

   For example:

   $ time COMMAND
   

   The command will execute and its output will be shown. Along with the output, the time command appends the time taken in stderr. An example is as follows:

   $ time ls
   test.txt
   next.txt
   real    0m0.008s
   user    0m0.001s
   sys     0m0.003s
   

   It will show real, user, and system times for execution.

   Note

   An executable binary of the time command is available at /usr/bin/time, as well as a shell built-in named time exists. When we run time, it calls the shell built-in by default. The shell built-in time has limited options. Hence, we should use an absolute path for the executable (/usr/bin...