How to find time taken by a command/program on Linux Shell?
We have already discussed a way to find time taken by a function through C libraries. If we are on Linux, then it becomes very easy to find time taken by a program/command.
We can use time command for this purpose. The time taken is shown in three forms.
real: Total end to end time taken by program/command
user: Time taken in user mode.
sys: Time taken in kernel mode
A Command Example (Time taken by ls-l):
$ time ls -l The above command runs "ls -l" and shows contents of current directory followed by the time taken by command "ls -l".
A program example (Time taken by fib(30)):
let us consider below program.
#include<stdio.h>int fib(int n){ if (n <= 1) return n; return fib(n-1) + fib(n-2);} int main (){ printf("Fibonacci Number is %d", fib(30)); return 0;} |
Let we save above program as fib.c. // Compiling above program on shell ~$ gcc fib.c // Running the generated executable with time ~$ time ./a.out Fibonacci Number is 832040 real 0m0.017s user 0m0.017s sys 0m0.000s Note: 0.017 seconds (shown with real) is total time taken by program.
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