Proc file system

Proc file system

The proc file system is a virtual file system. It uses the man proc command to describe proc as a pseudo file system. It provides some kernel data structure interfaces. Generally, the file system is mounted to the/proc Directory, which is usually read-only, but some files also allow some kernel variables to be modified.

Here are some examples:

// Obtain CPU information cat/proc/couinfo

Here are some of my outputs:


// Get the memory information cat/proc/meminfo

The output is as follows:
<喎?http: www.bkjia.com kf ware vc " target="_blank" class="keylink"> VcD4NCjxwPjxjb2RlIGNsYXNzPQ = "hljs mel"> There are many files in the proc file system that can obtain some useful information.
You can use man proc to understand the proc file system as a whole.

Based on my understanding of the proc file system, I use the C language to obtain some information in the current system, including:
| Question A |
| 1: CPU type |
| 2: kernel version |
| Question B |
| 1: system running time |
| Question C |
| 1: cpu status |
| 2: disk requests |
| 3: Number of context switches |
| 4: Total number of processes |
| Question D |
| 1: Total memory size |
| 2: available memory |
| 3: Average system load |

The following is my code:

/*************************************** * ***** Function: observe linux kernel behavior /*********************************** * ***********/# include  # Include  # Include  # Include  // FILE pointer, used to read some files in the proc FILE system * thisProcFile; // obtain the CPU type void CPUinfo () {char s [1000]; char gu [10] = "model name"; // open the file and read if (thisProcFile = fopen ("/proc/cpuinfo", "r ")) = NULL) {printf ("% s \ n", "Open file failed !! "); Exit (0);} while (fgets (s, 100, thisProcFile )! = NULL) {char * temp = strtok (s, ":"); if (strncmp (s, gu, 10) = 0) {// ": "For the delimiter to separate the string temp = strtok (NULL,": "); printf (" cputype: % s \ n ", temp); fclose (thisProcFile ); return ;}}// obtain the kernel version void Kernel_version () {char s [1000]; if (thisProcFile = fopen ("/proc/version", "r ")) = NULL) {printf ("% s \ n", "Open file failed !! "); Exit (0);} printf (" kernel version: \ n "); while (! Feof (thisProcFile) {if (fgets (s, 100, thisProcFile )! = NULL) printf ("% s", s);} fclose (thisProcFile);} // obtain the system runtime void time_run () {char s [100]; if (thisProcFile = fopen ("/proc/uptime", "r") = NULL) {printf ("% s \ n", "Open file failed !! "); Exit (0);} if (fgets (s, 100, thisProcFile )! = NULL) {char * temp = strtok (s, ""); int times = atoi (temp); // convert the time to int run_days = times/86400; int run_hours = (times % 86400)/3600; int run_minutes = (times % 3600)/60; int run_seconds = (times % 60); printf ("the system Runtime is: % d day % d hour % d minute % d Second \ n ", run_days, run_hours, run_minutes, run_seconds);} fclose (thisProcFile);} void sampleLoadAvg () {// observe system load char s [100]; if (thisProcFile = fopen ("/proc/loadavg "," R ") = NULL) {printf (" % s \ n "," Open file failed !! "); Exit (0);} fgets (s, 100, thisProcFile); fclose (thisProcFile); char * temp = strtok (s ,""); char * array [5]; int m = 0; while (temp! = NULL) {array [m] = temp; temp = strtok (NULL, ""); m ++;} printf ("Average number of processes in one minute: % s \ n ", array [0]); printf (" Average number of processes within five minutes: % s \ n ", array [1]); printf ("Average number of processes within 15 minutes: % s \ n", array [2]); printf ("Number of processes running/total number of processes: % s \ n ", array [3]); printf ("recently running process ID: % s \ n", array [4]); fclose (thisProcFile );} // obtain the CPU status void cpu_state () {char s [1000]; if (thisProcFile = fopen ("/proc/stat", "r") = NULL) {printf ("% s \ n", "Open file failed!! "); Exit (0);} if (fgets (s, 1000, thisProcFile )! = NULL) {char * temp = strtok (s, ""); char * array [11]; int m = 0; while (temp! = NULL) {array [m] = temp; temp = strtok (NULL, ""); m ++;} printf ("CPU time used to execute the user State: % s jiffies \ n ", array [1]); printf (" time used for CPU system state execution: % s jiffies \ n ", array [3]); printf ("CPU idle state execution time: % s jiffies \ n", array [4]) ;}fclose (thisProcFile );} // obtain the number of context switches void ctxt () {char s [1000]; char gu [4] = "ctxt "; if (thisProcFile = fopen ("/proc/stat", "r") = NULL) {printf ("% s \ n", "Open file failed !! "); Exit (0);} while (fgets (s, 100, thisProcFile )! = NULL) {char * temp = strtok (s, ""); if (strncmp (s, gu, 4) = 0) {temp = strtok (NULL, ""); printf ("Number of context switches: % s \ n", temp); fclose (thisProcFile); return ;}}} // obtain the number of Created processes void processes () {char s [1000]; char gu [9] = "processes "; if (thisProcFile = fopen ("/proc/stat", "r") = NULL) {printf ("% s \ n", "Open file failed !! "); Exit (0);} while (fgets (s, 100, thisProcFile )! = NULL) {char * temp = strtok (s, ""); if (strncmp (s, gu, 9) = 0) {temp = strtok (NULL, ""); printf ("the number of Created processes is % s \ n", temp); fclose (thisProcFile); return ;}}// obtain the total memory void MemTotal () {char s [100]; char gu [8] = "MemTotal"; if (thisProcFile = fopen ("/proc/meminfo", "r") = NULL) {printf ("% s \ n", "Open file failed !! "); Exit (0);} while (fgets (s, 100, thisProcFile )! = NULL) {char * temp = strtok (s, ":"); if (strncmp (s, gu, 8) = 0) {temp = strtok (NULL ,": "); printf (" total memory: % s \ n ", temp); fclose (thisProcFile); return ;}}// obtain the active memory void MemFree () {char s [100]; char gu [7] = "MemFree"; if (thisProcFile = fopen ("/proc/meminfo", "r") = NULL) {printf ("% s \ n", "Open file failed !! "); Exit (0);} while (fgets (s, 100, thisProcFile )! = NULL) {char * temp = strtok (s, ":"); if (strncmp (s, gu, 7) = 0) {temp = strtok (NULL ,": "); printf (" available memory: % s \ n ", temp); fclose (thisProcFile); return ;}} int main (int argc, char * argv []) {// sampleLoadAvg (); load balancing // CPUinfo (); // CPU information // Kernel_version (); // kernel version information // time_run (); // obtain the system running time // cpu_state (); // obtain the CPU status // ctxt (); // processes (); // MemTotal (); // MemFree (); char in; printf ("========================================== ===\ n "); printf ("| enter the question to view: | \ n"); printf ("| question A | \ n"); printf ("| 1: CPU type | \ n "); printf (" | 2: kernel version | \ n "); printf (" | Problem B | \ n "); printf (" | 1: system running time | \ n "); printf (" | Problem C | \ n "); printf (" | 1: cpu status | \ n "); printf ("| 2: Number of disk requests | \ n"); printf ("| 3: Number of context switches | \ n"); printf ("| 4: total number of processes | \ n "); printf (" | problem D | \ n "); printf (" | 1: Total memory | \ n "); printf (" | 2: available memory | \ n "); printf (" | 3: Average system load | \ n "); printf ("========================================== ===\ n "); scanf ("% c", & in); if (in = 'A') {CPUinfo (); Kernel_version (); // kernel version information} else if (in = 'B') {time_run (); // obtain system runtime} else if (in = 'C ') {cpu_state (); // obtain the CPU status ctxt (); processes () ;}else if (in = 'D') {MemTotal (); // total memory MemFree (); // available memory sampleLoadAvg (); // average system load }}    

Below are some of my outputs: