find <search dir> -type <file or dir> -name <pattern file name>  
   
 Ex:  
 find /home/user/Downloads -type f -name "*.rar"  
 Tìm kiếm tất cả các file nén .rar trong thư mục Downloads  

 sed -i "s:<string to search>:<string to replace>:" infile outfile   
 or   
 sed -i "s:<string to search>:<string to replace>:" filename 
 # tim, thay the va save filename  
    
 Ex:  
 sed -i "s:day:night:" testfile.txt  
   

 #!/bin/sh  
   
 # Tao listfile.txt luu danh sach tat ca cac file trong thu muc Downloads  
 #find /home/ninhld/Downloads -type f -name '*' > /home/ninhld/Downloads/listfile.txt  
   
 #Duyet qua tat ca cac file trong thu muc Downloads, search va replace tat ca   
 #cac file ma noi dung co noi dung /home/ninhld/Downloads  
 FINDPATH="/home/ninhld/Downloads"   
 FILETYPE="*"   
 PATTERN="/home/ninhld/Downloads"  
 REPLACE=""  
   
 find $FINDPATH -type f -name "$FILETYPE" -exec sed -i "s:$PATTERN:$REPLACE:" {} +  
   
 #for FILE in $(find $FINDPATH -type f)  
 #do  
 #     #echo $FILE  
 #     sed -i "s:$FINDPATH::" $FILE  
 #done  
   

 #include <stdio.h>  
 #include <stdbool.h>  
 #include <stdlib.h>  
   
 int main(int argc, char **argv){  
   
   int idata; /* default: 0 */  
   bool bdata; /* default: false */  
   float *pdata; /* default: NULL */  
   
   
   if(!idata){  
     /* code here */  
     printf("goto here 1\n");  
   }  
   
   if(!bdata){  
     /* code here */  
     printf("goto here 2\n");  
   
   }  
   
   
   if(!pdata){  
     /* code here */  
     printf("goto here 3\n");  
     pdata = (float*)malloc(sizeof(float));  
   }  
   
   *pdata = 10;  
   free(pdata);  
   
   
   return 1;  
 }  
   

 int idata = 0;  
 bool bdata = false;  
 float *pdata = NULL;  

 #ifndef RINGBUFFER_H  
 #define RINGBUFFER_H  
   
 #ifdef __cplusplus  
 extern "C" {  
 #endif  
   
 #include <stddef.h>  
 #include <stdbool.h>  
   
 /*  
  * ringbuffer.h - C ring buffer (FIFO) interface.  
  */  
 typedef struct ringbuffer_t  
 {  
   void *buffer;   // data buffer  
   void *buffer_end; // end of data buffer  
   size_t capacity; // maximum number of items in the buffer  
   size_t count;   // number of items in the buffer  
   size_t sz;    // size of each item in the buffer  
   void *head;    // pointer to head  
   void *tail;    // pointer to tail  
 } ringbuffer_t;  
   
 bool ring_init(ringbuffer_t *cb, size_t capacity, size_t sz);  
   
 bool ring_free(ringbuffer_t *cb);  
   
 bool ring_push_head(ringbuffer_t *cb, const void *item);  
   
 bool ring_pop_tail(ringbuffer_t *cb, void *item);  
   
 #ifdef __cplusplus  
 }  
 #endif  
   
 #endif /* RINGBUFFER_H */  
   

 #include "ringbuffer.h"  
 #include <assert.h>  
 #include <stdlib.h>  
 #include <string.h>  
 #include <stdio.h>  
   
 bool ring_init(ringbuffer_t *cb, size_t capacity, size_t sz)  
 {  
   cb->buffer = malloc(capacity * sz);  
   if(cb->buffer == NULL){  
     printf("ring_init FAIL ! \n");  
     return false;  
   }  
   
   cb->buffer_end = (char *)cb->buffer + capacity * sz;  
   cb->capacity = capacity;  
   cb->count = 0;  
   cb->sz = sz;  
   cb->head = cb->buffer;  
   cb->tail = cb->buffer;  
   return true;  
 }  
   
 bool ring_free(ringbuffer_t *cb)  
 {  
   if(cb->buffer){  
     free(cb->buffer);  
     cb->buffer = NULL;  
   }else{  
     return false;  
   }  
   return true;  
 }  
   
 bool ring_push_head(ringbuffer_t *cb, const void *item)  
 {  
   if(cb->count == cb->capacity){  
     printf("Ringbuffer is Full ! \n");  
     return false;  
   }  
   
   memcpy(cb->head, item, cb->sz);  
   cb->head = (char*)cb->head + cb->sz;  
   if(cb->head == cb->buffer_end)  
     cb->head = cb->buffer;  
   cb->count++;  
   
   return true;  
 }  
   
 bool ring_pop_tail(ringbuffer_t *cb, void *item)  
 {  
   if(cb->count == 0){  
     printf("Ringbuffer is Empty ! \n");  
     return false;  
   }  
   
   memcpy(item, cb->tail, cb->sz);  
   cb->tail = (char*)cb->tail + cb->sz;  
   if(cb->tail == cb->buffer_end)  
     cb->tail = cb->buffer;  
   cb->count--;  
   return true;  
 }  
   

 #include <string.h>  
 #include <unistd.h>  
 #include <stdio.h>  
 #include <stdlib.h>  
 #include <assert.h>  
 #include "ringbuffer.h"  
   
 #define CAPACITY 10  
 typedef struct data_t{  
   int idata;  
   float fdata;  
 }data_t;  
   
 ringbuffer_t ringbf;  
   
   
 int main(int argc, char **argv)  
 {  
     
   ring_init(&ringbf, CAPACITY, sizeof(data_t));  
   
   int i;  
   data_t tmpdata;  
   
   for(i = 0; i < CAPACITY; i++){  
     tmpdata.idata = i;  
     tmpdata.fdata = i+1;  
     ring_push_head(&ringbf, (void*)&tmpdata);  
     printf("number of items: %d \n", ringbf.count);  
   }  
   
   for(i = 0; i < CAPACITY; i++){  
     ring_pop_tail(&ringbf, (void*)&tmpdata);  
   
     printf("number of items: %d, idata: %d, fdata: %f \n", ringbf.count, tmpdata.idata, tmpdata.fdata);  
   
   }  
     
   ring_free(&ringbf);  
   return 0;  
 }  
   

 enum player_status_t{  
      ST_TOPPED = 0;  
      ST_PLAYING,  
      ST_PAUSED,  
      ST_FFW,    /* fast forward */  
      ST_FBW,    /* fast backward */       
 }  

 union myname_t{  
      char full_name[64];  
      char alias[32];  
 }    

 struct persion_t{  
      char name[32];  
      int age;  
 }  

 enum PlayerStatus_t{  
      ST_TOPPED = 0;  
      ST_PLAYING,  
      ST_PAUSED,  
      ST_FFW,    /* fast forward */  
      ST_FBW,    /* fast backward */       
 }  

 void set_value(int a){  
      /* code here */  
        
 }  
   
 int get_value(){  
      int ret_value = 0;  
      /* code here */  
        
      return ret_value;  
 }  

 typedef int (*math_operator_t)(int a, int b);  

 void setValue(int a){  
      /* code here */  
        
 }  
   
 int getValue(){  
      int ret_value = 0;  
      /* code here */  
        
      return ret_value;  
 }  

 typedef int (*MathOperator_t)(int a, int b);  

 player_status_t m_player_status = ST_TOPPED;  
   
 hoặc  
   
 player_status_t g_player_status = ST_TOPPED;  
   

 player_status_t l_player_status = ST_TOPPED;     

 int ndata;  
 float fdata;  
 string strdata;  

 user_controller.h  
 user_controller.c    

 user_controller.hpp  
 user_controller.cpp   

 class Button:public sigslot::has_signals<Button>  
 {  
   //attributes  
   //methods  

 public __signals:  
   sigslot::signal<char*> touchEvent;  
 };  

 class View:public sigslot::has_slots<>  
 {  
   //attributes  
   //methods  
   
 public __slots:  
   void onUpdate(char *msg){  
     cout << "recvmsg: " << msg <<endl;  
   }  
 };   

 class TransRecv:public sigslot::has_signals<TransRecv> , sigslot::has_slots<>  
 {  
     //attributes  
     //methods  
   
 public __signals:  //phat signal cho object A 
      sigslot::signal<char *> touchPoint;  
   
 public __slots:    //nhan signal tu object B 
      void onUpdate(float fdata, int idata);  
 };  

 #include <iostream>  
 #include "sigslot.h"  
   
 using namespace std;  
   
 class Button:public sigslot::has_signals<Button>  
 {  
 public:  
   Button(){ };  
   virtual ~Button(){ };  
   
   void onClick(){  
     touchEvent.emit((char*)"Hello, I am button");  
   }  
   
 public __signals:  
   sigslot::signal<char*> touchEvent;  
   
 };  
   
 class View:public sigslot::has_slots<>  
 {  
 public:  
   View(){ };  
   virtual ~View(){ };  
   
 public __slots:  
   void onUpdate(char *msg){  
     cout << "recvmsg: " << msg <<endl;  
   }  
 };  
   
 int main(int argc, char **argv){  
   
   Button btn;  
   View view;  
   
   btn.touchEvent.connect(&view, &View::onUpdate);  
   btn.onClick();  
   return 1;  
 }  
   

 $ g++ sigslot.h main.cpp   
 $ ./a.out   
 recvmsg: Hello, I am button