This really depends on the country of study.
In UK a student has to attain a job which will pay them approximately GBP 24,000 per year and they should be able to work for 2 years.
In USA students get 1 year or 2 years of Optional Practical Training permit depending on the nature of their degree. During this OPT period, students are allowed to work in any institution that will recruit them.
In Canada students get the opportunity to work up to 3 years depending on the length of their degree.
In Japan and Malaysia students need to attain employment at a company which will sponsor them for an employment visa. Most of our students in Japan are able to secure employment before graduation and are able to extend their permission to stay.