（standard c libraries translation ）logwtmp

updwtmp, logwtmp - append an entry to the wtmp file
updwtmp, logwtmp - 增加入口到wtmp文件尾部

所需头文件
#include <utmp.h>

void updwtmp(const char *wtmp_file, const struct utmp *ut);
void logwtmp(const char *line, const char *name, const char *host);

updwtmp() appends the utmp structure ut to the wtmp file.
logwtmp()  constructs a utmp structure using line, name, host, current time and current process ID.  Then it calls updwtmp() to append the structure to the wtmp file.
updwtmp增加utmp结构体ut到wtmp文件尾部
logwtmp用line，name，host，current time和current process ID来构建一个utmp的结构体，然后调用updwtmp把这个结构体附加到wtmp文件尾部

FILES /var/log/wtmp database of past user logins
历史用户登陆数据库

Both functions are available under glibc2, but not under libc5.  However, logwtmp() used to occur in the old libbsd.  These days, the  logwtmp()  function is included in libutil.  (Hence you'll need to add -lutil to your compiler command line to get it.)
这两个函数都在glibc2中有提供，但是在libc5中没有提供，然而logwtmp曾经在老版的libbsd中存在过，近来logwtmp函数包含在libutil

For consistency with the other "utmpx" functions (see getutxent(3)), glibc provides (since version 2.1):
#include <utmpx.h>
void updwtmpx (const char *wtmpx_file, const struct utmpx *utx);
This function performs the same task as updwtmp(), but differs in that it takes a utmpx structure as its last argument.
为了与另一个utmpx函数保持一致性，glibc提供了updtmpx函数
这个函数与updwtmp函数作用一样，但是它使用utmpx结构体作为后一个参数