A preliminary understanding of UNIX environment programming--process



Some knowledge about the process was studied in the previous period, which was divided into three parts: process environment, process relation, Process control. Below is my mind map and related understanding. Due to lack of practice, many of these areas are not well understood.

Mind Mapping:

Process Environment:

1, start / Stop: The environment of the process, first of all, the overall environment of the process of understanding, through the analysis of the start and end of the C language, explains how the process is started and terminated. 2, the Environment table: explains that for each program will receive an environment table. 3. Space allocation: For spatial allocation, including: the layout of storage space in C program, the origin and execution method of shared library, some function application of storage space allocation and its different functions. 4, environment variables: in-depth understanding of the application of environmental variables, while learning the application of two groups of functions, namely, the jump on the cross-function and with the query and modify the process of the resource constraints of the function.

Process Control:

1, Process identity: Each process has a unique process ID, called process identity, the control of the process needs to take the identity as the corresponding basis;2. New process: This paper analyzes the process of creating a new process and the application of its related functions. The execution of the new process requires that a child process be created first and then executed by calling exec to perform a program completion. 3, termination: At the same time in this section again analysis of the process of the termination process and the termination process. 4, access to information: Explain the function of information acquisition, each process has its own corresponding property information, including information about the status of the process, the relevant time information about the process, the resource profile of the process used, the user login name of the running program. 5. Change ID: Based on permissions issues in the process, sometimes you need to change the user's ID and group ID. 6, process accounting: As a process accounting processing, it will record some of the relevant information about the process. 7, process scheduling: about the execution of a process and A nice value, you can change the schedule of a process by changing the value.

Process Relationship:

1, Process group: about process relations, from the most basic process to understand, a number of processes can constitute a process group, which explains the creation of process groups, set up, return and other operational functions of the use of understanding about the orphan process group concept. 2, session: Multiple process groups constitute a session,3, Job Control: The overall understanding of the process of implementation process and related processes, process groups, sessions and other concepts between the relationship.

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A preliminary understanding of UNIX environment programming--process