The framework in which a process carries on its activities is its processing environment. The processing environment consists of a number of components . A series of identification numbersprocess ID, parent process ID, and process group IDare used to reference the individual process, its parent, and the group with which the process is affiliated . In its environment a process has access to resources (i.e., files and devices). Access to these resources is determined by permissions that are initially set when the resource is generated. When accessing files, a process can obtain additional system information about the resource. All processes are constrained by system-imposed resource limits. A process can obtain limit information using the appropriate system call or library function. Processes may receive signals that in turn may require a specific action. The values passed via the command line to the process can be obtained. In addition, the process has access to, and may modify (in some settings), environment variables . Linux also supports a /proc directory that contains special files with information about the kernel, its data structures, and all active processes.
Programs and Processes
Remote Procedure Calls
Appendix A. Using Linux Manual Pages
Appendix B. UNIX Error Messages
Appendix C. RPC Syntax Diagrams
Appendix D. Profiling Programs