[英]How to extract information from the content of /proc files on Linux using C?
I have been working on this for over 7 hours a day for 5 days.我一直在为此工作 5 天,每天超过 7 小时。 I am not exactly the best coder, so I need some help.
我不是最好的编码员,所以我需要一些帮助。 I need to know how should I get the info from /proc using a C program on Linux.
我需要知道如何在 Linux 上使用 C 程序从 /proc 获取信息。 The info has to be printed out and include the following:
信息必须打印出来,并包括以下内容:
It sounds like you don't know where to start.听起来你不知道从哪里开始。 Let me try to explain the information in
/proc
:让我尝试解释
/proc
的信息:
If we cat /proc/29519/stat
, we get this info:如果我们
cat /proc/29519/stat
,我们会得到以下信息:
29519 (vim) S 5997 29519 5997 34835 29519 24576 1275 0 47 0 5 0 0 0 20 0 2 0 49083340 188043264 3718 18446744073709551615 4194304 6665820 140737488349264 140737488347024 140737280970147 0 0 12288 1837256447 18446744073709551615 0 0 17 3 0 0 21 0 0 8764120 8861948 8925184 140737488349925 140737488349929 140737488349929 140737488351211 0
What do all those numbers represent?所有这些数字代表什么? The answer is in man proc , in the section called
/proc/[pid]/stat
.答案在man proc 中,在名为
/proc/[pid]/stat
。 From this we see the first four things are:由此我们看到前四件事是:
pid %d
pid %d
(1) The process ID.
(1) 进程标识。
comm %s
通讯 %s
(2) The filename of the executable, in parentheses.
(2) 可执行文件的文件名,在括号中。 This is visible whether or not the executable is swapped out.
无论可执行文件是否被换出,这都是可见的。
state %c
状态 %c
(3) One character from the string "RSDZTW" where R is running, S is sleeping in an interruptible wait, D is waiting in uninterruptible disk sleep, Z is zombie, T is traced or stopped (on a signal), and W is paging.
(3) 字符串“RSDZTW”中的一个字符,其中 R 正在运行,S 在可中断等待中休眠,D 在磁盘不可中断休眠中等待,Z 是僵尸,T 被跟踪或停止(在信号上),W 是分页。
ppid %d
ppid %d
(4) The PID of the parent.
(4) 父母的PID。
With this knowledge we can parse it out with fscanf(f, "%d %s %c %d", ...)
:有了这些知识,我们可以用
fscanf(f, "%d %s %c %d", ...)
解析它:
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
void main(int argc, char **argv) {
int pid;
sscanf(argv[1], "%d", &pid);
printf("pid = %d\n", pid);
char filename[1000];
sprintf(filename, "/proc/%d/stat", pid);
FILE *f = fopen(filename, "r");
int unused;
char comm[1000];
char state;
int ppid;
fscanf(f, "%d %s %c %d", &unused, comm, &state, &ppid);
printf("comm = %s\n", comm);
printf("state = %c\n", state);
printf("parent pid = %d\n", ppid);
fclose(f);
}
Now if I compile that file and run ./a.out 29519
, I get现在,如果我编译该文件并运行
./a.out 29519
,我会得到
pid = 29519
comm = (vim)
state = S
parent pid = 5997
Does that give you enough information to get started?这是否为您提供了足够的信息以开始使用?
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