Processes in Linux

The main task of operating systems is to execute computer programs. When each program is started, one or more processes are created, which effectively represent program code in execution. But in addition to static code, they also consist of data, resources, state, and a virtualized computer.

In Linux, each process is represented by a unique identifier called pid. When there are no active processes, the operating system idlely runs a special idle process (Term in English: Idle Process), which has the unique identifier pid = 0.

Processes can create other processes, with the original process referred to as the parent and the newly created one called the child. In this way, hierarchical groups of processes are created, which can communicate and share resources with each other.

Every process is owned by a user and a group registered in the operating system. In most cases, it is the user who launched the application and the corresponding group to which they belong.