Way to measure time of execution program - c

Question

I have a lots of short programs in C. Each program realize simple operation for example: include library, load something (ex matrix) from file, do simple operation, write matrix to file end.
I want to measure real time of excecution a whole program (not only fragment of code).
My simple idea is using htop or ps aux -> column time. But this method isn't good because I don't have exacly time of execution but time of excecution during last refresh and I can miss this.
Do you have any method to measure time of process in linux?

Answer 1

If your program is named foo, then simply typing
~$ time foo
should do exactly what you want.

Answer 2

In addition to other answers, mostly suggesting to use the time utility or shell builtins:
time(7) is a very useful page to read.
You might use (inside your code) the clock(3) standard function to get CPU time in microseconds.
Resolution and accuracy of time measures depends upon hardware and operating system kernel. You could prefer a "real-time" kernel (e.g. a linux-image-3.2.0-rt package), or at least a kernel configured with CONFIG_HZ_1000) to get more precise time measures.
You might also use (inside your code) the clock_gettime(2) syscall (so link also the -lrt library).
When doing measurements, try to have your measured process run a few seconds at least, and measure it several times (because e.g. of disk cache issues).

Answer 3

If you use
time <PROGRAM> [ARGS]
this will provide some base-level information. This should run your shell's time command. Example output:
$ time sleep 2
real 0m2.002s
user 0m0.000s
sys 0m0.000s
But there is also
/usr/bin/time <PROGRAM> [ARGS]
which is more flexible and provides considerably more diagnostic information regarding timing. This runs a GNU timing program. This site has some usage examples. Example output:
$ /usr/bin/time -v sleep 2
Command being timed: "sleep 2"
User time (seconds): 0.00
System time (seconds): 0.00
Percent of CPU this job got: 0%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.00
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 2496
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 0
Minor (reclaiming a frame) page faults: 202
Voluntary context switches: 2
Involuntary context switches: 1
Swaps: 0
File system inputs: 0
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0