System Programming Knowledge Summary

1.Linux Operating System

Multi-user

2.shell

Command line interpreter consumer <--> core

Interpreted type rather than compiled

Run Program Fork Child process EXECV function cluster Replace user-specified program wait process end

3.vim, gcc/g++ (using dynamic libraries by default at compile time), GDB, make ($foreach <var>,<list>,<text>), CATGS

4. Environment variables

command echo, export, env, set

5. Common commands

6. files (functions of file attributes and operation files)

File type: Normal file (-), catalog file (d), Pipeline file (p), device file (b C),

Socket (s), linked file (l)

File information: stat (), Fstat (), Lstat () struct stat{};

File access permissions and related settings:

Each file has 9 access bits CHOMD command, umask function (file mode creates a mask word, returns without error)

Set file uid and GID, chown

File system

Hard Link ln Source file destination file link ();

Soft link ln-s source file destination file symlink ();

File time: St_atime, St_mtime, St_ctime

7. File i/0

File descriptor

Open (), read (), write (), Lseek (), Close ()

DUP ()

8. Standard I/O Library

standard input, standard output, standard error

Buffer

9. Process Environment

Main () function

Command-line arguments

Process termination

Environment tables and environment variables

C-language storage space layout

10. Process Control

pid_t getpid (void);

Process concept: A running program, its basic two elements are program code and program associated data set

Pcb:linux is called task_struct, which holds information about the process and can be understood as a collection of process properties

Process identifiers: Each process is represented by a unique non-negative integer type

Ppid, UID, GID, Euid, egid, can be obtained by corresponding function

Change user ID and Group Id:setuid () Setgid ()

Status of the process: R S D (disk sleep state) T T Z X

Priority: Ps-l command PRI the smaller the value of this column, the sooner the process is executed NI represents the nice value of the process, PRI (new) =pri (old) +nice

Process creation: fork (), vfork () zombie process, orphan process

Process wait: Wait (), Waitpid ()

Process program substitution: exec ()

Process termination: 8 kinds

5: Return from the main function, Exit in any thread (), call _eixt () or _exit (), go back from the last thread, call the last thread Pthread_exit

3: Call abort function, last thread responds to cancellation request, receives termination signal

11. Inter-Process relations

Terminal login, Terminal control

Process groups, sessions, jobs

12. Signal

Signal concept: A signal is a technique that notifies a process that a situation has occurred

How the signal is produced: three kinds

Signal blocking and recursion: recursive, pending signal set operation function change or read signal mask read pending signal set

Capture of Signals

reentrant functions

callback function

Race condition: Error caused by timing problem

The signal mechanism is stored in the PCB

13. Threading Control

pthread_t pthread_self (void);

Concept: Sometimes you need to execute multiple control flows in one process

The difference from a process: a thread is an execution branch running in a process that is the basic unit of a resource allocation, a fundamental element of a thread dispatch, a process that emphasizes exclusivity, and a thread that emphasizes sharing

Line programming: thread creation, thread termination, thread waiting

The thread function in return, Pthread_exit (void*) terminates itself, int pthread_cancle (pthread_t) cancels other threads in the unified process), and if any one of the threads calls exit or _exit, Then all threads of the entire process are terminated

Thread separation: The default state is set to a binding, but it can be set to detach state

Thread synchronization: Mutex (possibly deadlock), condition variable (typical example producer consumer model), POSIX semaphore (producer consumer model based on ring BUF), read-write lock

Thread-Private data:

Thread safety and Reentrant functions:

14. Inter-process communication

Four cases of end write end of pipe one-way communication

FIFO Creation (MKFIFO)

Message Queuing

Signal Volume

Shared memory

15. Daemon Process

This article is from the "Zero Egg" blog, please be sure to keep this source http://lingdandan.blog.51cto.com/10697032/1771991

System Programming Knowledge Summary