inotify只能监控单层目录变化，不能监控子目录中的变化情况。

inotify只能监控单层目录变化，不能监控子目录中的变化情况。
如果需要监控子目录，需要在调用inotify_add_watch(int fd, char *dir, int mask):int建立监控时，递归建立子目录的监控，伪代码如下
void addwatch(int fd, char *dir, int mask)
{
wd = inotify_add_watch(fd, dir, mask);
向目录集合加入(wd, dir);
for (dir下所有的子目录subdir）
addwatch(fd, subdir, mask);
}
这样就可以得到一个目录集合，其中每一个wd对应一个子目录。
当你调用read获取信息时，可以得到一个下面的结构体
struct inotify_event
{
int wd; /* Watch descriptor. */
uint32_t mask; /* Watch mask. */
uint32_t cookie; /* Cookie to synchronize two events. */
uint32_t len; /* Length (including NULs) of name. */
char name __flexarr; /* Name. */
};
其中，通过event->wd和刚才记录的目录集合可以知道变动的具体子目录。
event->name为具体的文件名称。
event->name是一个char name[0]形式的桩指针，具体的name占据的长度可以由event->len得出

我的监控部分代码如下：
enum {EVENT_SIZE = sizeof(struct inotify_event)};
enum {BUF_SIZE = (EVENT_SIZE + 16) << 10};
void watch_mon(int fd)
{
int i, length;
void *buf;
struct inotify_event *event;
buf = malloc(BUF_SIZE);

while ((length = read(fd, buf, BUF_SIZE)) >= 0)
{
i = 0;
while (i < length)
{
event = buf + i;
if (event->len)
具体处理函数(event);
i += EVENT_SIZE + event->len;
}
}
close(fd);
exit(1);
}
在你的具体处理函数中，通过wd辨识子目录，通过name辨识文件

这是利用C++STLmap写的一个范例，可以监视当前目录下（含子目录）的变化，创建，删除过程（新建立的目录不能监视，只能通过监视到创建新目录的事件后重新初始化监视表）
新版1.1.0，可以监视创建的子目录，方法是，当do_action探测到新目录创建的动作时，调用inotify_add_watch追加新的监视
/*
Copyright (C) 2010-2011 LIU An (SuperHacker@china.com.cn)

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

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

#include <unistd.h>
#include <sys/types.h>
#include <sys/inotify.h>
#include <errno.h>
#include <dirent.h>

#include <map>
#include <string>
using namespace std;

void addwatch(int, char*, int);
static int filter_action(uint32_t mask);
int watch_init(int mask, char *root);
void addwatch(int fd, char *dir, int mask);
static void do_action(int fd, struct inotify_event *event);
void watch_mon(int fd);
static void send_mess(char *name, char *act, int ewd);
void append_dir(int fd, struct inotify_event *event, int mask);

map<int, string> dirset;

enum{MASK = IN_MODIFY | IN_CREATE | IN_DELETE};

int main(int argc, char **argv)
{
int fd;
if (argc != 2)
{
fprintf(stderr, "Usage: %s dir\n", argv[0]);
exit(1);
}

fd = watch_init(MASK, argv[1]);
watch_mon(fd);

return 0;
}

int watch_init(int mask, char *root)
{
int i, fd;

if ((fd = inotify_init()) < 0)
perror("inotify_init");
addwatch(fd, root, mask);
return fd;
}

void addwatch(int fd, char *dir, int mask)
{
int wd;
char subdir[512];
DIR *odir;
struct dirent *dent;

if ((odir = opendir(dir)) == NULL)
{
perror("fail to open root dir");
exit(1);
}
wd = inotify_add_watch(fd, dir, mask);
dirset.insert(make_pair(wd, string(dir)));

errno = 0;
while ((dent = readdir(odir)) != NULL)
{
if (strcmp(dent->d_name, ".") == 0
|| strcmp(dent->d_name, "..") == 0)
continue;
if (dent->d_type == DT_DIR)
{
sprintf(subdir, "%s/%s", dir, dent->d_name);
addwatch(fd, subdir, mask);
}
}

if (errno != 0)
{
perror("fail to read dir");
exit(1);
}

closedir (odir);
}

enum {EVENT_SIZE = sizeof(struct inotify_event)};
enum {BUF_SIZE = (EVENT_SIZE + 16) << 10};

void watch_mon(int fd)
{
int i, length;
void *buf;
struct inotify_event *event;
buf = malloc(BUF_SIZE);

while ((length = read(fd, buf, BUF_SIZE)) >= 0)
{
i = 0;
while (i < length)
{
event = (struct inotify_event*)(buf + i);
if (event->len)
do_action(fd, event);
i += EVENT_SIZE + event->len;
}
}
close(fd);
exit(1);
}

static char action[][10] =
{
"modified",
"accessed",
"created",
"removed"
};

enum{NEWDIR = IN_CREATE | IN_ISDIR};

static void do_action(int fd, struct inotify_event *event)
{
int ia, i;

if ((ia = filter_action(event->mask)) < 0)
return;

if ((event->mask & NEWDIR) == NEWDIR)
append_dir(fd, event, MASK);

send_mess(event->name, action[ia], event->wd);
}

void append_dir(int fd, struct inotify_event *event, int mask)
{
char ndir[512];
int wd;

sprintf(ndir, "%s/%s", dirset.find(event->wd)->second.c_str(),
event->name);
wd = inotify_add_watch(fd, ndir, mask);
dirset.insert(make_pair(wd, string(ndir)));
}

static int filter_action(uint32_t mask)
{
if (mask & IN_MODIFY)
return 0;
if (mask & IN_ACCESS)
return 1;
if (mask & IN_CREATE)
return 2;
if (mask & IN_DELETE)
return 3;
return -1;
}

static void send_mess(char *name, char *act, int ewd)
{
char format[] = "%s was %s.\n";
char file[512];

sprintf(file, "%s/%s", dirset.find(ewd)->second.c_str(), name);

printf(format, file, act);
}

参考资料是我们作业的提交，没有考虑递归创建子目录监控的问题。
参考资料：[url]http://59.67.33.217/homeworkref/sources/2010-2011-1.2008.software.os.inotify.tar.xz[/url]
转： [url]http://zhidao.baidu.com/question/218179319.com[/url]