提取proc / status linux文件的一部分

Question

First, I'm totally beginner in linux and C language, I can't relate C to c++ or java much when it comes to strings!. I'm using Fedora16 - linux - and I want to read a proc/[pid]/status file to get specific information from it, such as PPID and state, then I should print these info on the screen - command line terminal-. This must be done by writing ac script in gedit. My only issue is that I'm new to c, and dealing with strings in c seems very frustrating to me! I have already opened the file and view it on my terminal by executing the c file. Is there any possible way to store the whole content in one string variable and then I can tokenize it and store the chunks of data as in string array not char array, then I know where my wanted data is in the array and I can access it?

Here is my code though

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

void main()
{


const char line[200];
const char junk[200];

FILE *file = fopen("/proc/14/status", "r");

// while not end of the file
while(!feof(file)) {

fscanf(file,"%s",line); //Get text into line array

printf("%s\n", line);

//fscanf(file,"%[ \n\t\r]s",junk); //Remove any 'white space' characters

               }//end while

fclose(file);

}

Output On Terminal:

Answer 1

There are two things wrong initially

1. line should not be const .
2. while (!feof(file)) is almost always wrong.

The fix involves doing something like

while (fscanf(file, "%199s", line) == 1)

which will loop until there is no more data and will prevent overflowing line .

This will fix something, the other thing is rather complicated, first try using fgets() instead if fscanf() , it will consume lines from the file including the '\\n' and the embedded white spaces

while (fgets(line, sizeof(line), file) != NULL)

then you can try sscanf() checking it's return value to ensure that it succeeded.

From the content of /proc/self/status you can see that strchr() would do a good job in splitting the lines in the interesting parts.

This is an example:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>

int
main(void)
{
    FILE *file;
    char line[100];
    file = fopen("/proc/self/status", "r");
    if (file == NULL)
        return -1; /* Failure to open /proc/self/stat -- very unlikely */
    while (fgets(line, sizeof(line), file) != NULL)
    {
        char *tail;
        char *key;
        char *value;
        tail = strchr(line, '\n');
        if (tail != NULL)
            *tail = '\0'; /* remove the trailing '\n' */
        tail = strchr(line, ':');
        if (tail != NULL)
        {
            tail[0] = '\0';
            key = strdup(line);
            if (key == NULL)
                continue;
            tail += 1;
            while ((tail[0] != '\0') && (isspace((int) tail[0]) != 0))
                tail++;
            value = strdup(tail);
            if (value != NULL)
            {
                fprintf(stderr, "%s --> %s\n", key, value);
                /* You could do something now with key/value */
                free(value);
            }
            free(key);
        }
    }
}