getpwent系统调用

getpwent系统调用

NAME
       getpwent, setpwent, endpwent - get password file entry

SYNOPSIS
       #include <sys/types.h>
       #include <pwd.h>

       struct passwd *getpwent(void);

       void setpwent(void);

       void endpwent(void);

struct passwd {
               char   *pw_name;       /* username */
               char   *pw_passwd;     /* user password */
               uid_t   pw_uid;        /* user ID */
               gid_t   pw_gid;        /* group ID */
               char   *pw_gecos;      /* user information */
               char   *pw_dir;        /* home directory */
               char   *pw_shell;      /* shell program */
           };

测试代码：

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

#define DEBUG_INFO(...) \
    do{\
        printf("%s:%d -- ", __func__, __LINE__);\
        printf(__VA_ARGS__); \
        printf("\n"); \
    }while(0)

int main(int argc, char **argv)
{
    struct passwd *p;
    int count = 0;
    do{
        p = getpwent();
        if(!p){
            perror("getpwent");
            break;
        }
        // DEBUG_INFO("pw_name=%s,pw_passwd=%s,pw_uid=%d,pw_gid=%d,"
        // "pw_gecos=%s,pw_dir=%s,pw_shell=%s", 
        // p->pw_name,
        // p->pw_passwd,
        // p->pw_uid,
        // p->pw_gid,
        // p->pw_gecos,
        // p->pw_dir,
        // p->pw_shell);
        DEBUG_INFO("%s:%s:%d:%d:%s:%s:%s", 
        p->pw_name,
        p->pw_passwd,
        p->pw_uid,
        p->pw_gid,
        p->pw_gecos,
        p->pw_dir,
        p->pw_shell);


        count++;
    }while(1);
    DEBUG_INFO("count: %d\n", count);
    return 0;
}

执行结果：

main:39 -- root:x:0:0:root:/root:/bin/bash
main:39 -- daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
/*略*/
getpwent: Success
main:44 -- count: 56