Difference between “system” and “exec” in Linux?

Question

What is the difference between system and exec family commands? Especially I want to know which one of them creates child process to work?

Answer 1

System() will create child process and invoke another sub shell while exec() will not create child process.Given Example will clear difference.

some code...

exec('ls -l')

echo "1 2 3" // This will not executed in bash (as exec command use same shell)

some code ...

system (ls -l) echo "1 2 3" // This will be executed after finishing System child process as they are different from parent PID.