linux系統編程快速定位標頭檔的技巧之強大的grep命令，linuxgrep

linux系統編程快速定位標頭檔的技巧之強大的grep命令，linuxgrep

這個技巧來自於我的實際開發碰到的：

inet_addr這個函數用於把ip地址轉成網路位元組序，他的原型：in_addr_t inet_addr(const char *cp);

傳回值為一個in_addr_t的類型，很顯然這不是一個c語言的標準資料類型，想搞清楚他到底是什麼類型，肯定要找到標頭檔，在linux系統上，標頭檔一般放在/usr/include下面，但是這下面非常多的標頭檔，根本不知道是哪個，所以：

1，第一次：grep in_addr_t /usr/include/*.h  沒有結果，說明不在/usr/include的第一層目錄中

2，第二次: grep "in_addr_t" /usr/include/*/*.h， 這一次出現很多結果

/usr/include/arpa/inet.h:extern in_addr_t inet_addr (const char *__cp) __THROW;/usr/include/arpa/inet.h:extern in_addr_t inet_lnaof (struct in_addr __in) __THROW;/usr/include/arpa/inet.h:extern struct in_addr inet_makeaddr (in_addr_t __net, in_addr_t __host)/usr/include/arpa/inet.h:extern in_addr_t inet_netof (struct in_addr __in) __THROW;/usr/include/arpa/inet.h:extern in_addr_t inet_network (const char *__cp) __THROW;/usr/include/arpa/inet.h:extern char *inet_neta (in_addr_t __net, char *__buf, size_t __len) __THROW;/usr/include/netinet/in.h:typedef uint32_t in_addr_t;/usr/include/netinet/in.h:    in_addr_t s_addr;/usr/include/netinet/in.h:#define    IN_CLASSA(a)        ((((in_addr_t)(a)) & 0x80000000) == 0)/usr/include/netinet/in.h:#define    IN_CLASSB(a)        ((((in_addr_t)(a)) & 0xc0000000) == 0x80000000)/usr/include/netinet/in.h:#define    IN_CLASSC(a)        ((((in_addr_t)(a)) & 0xe0000000) == 0xc0000000)/usr/include/netinet/in.h:#define    IN_CLASSD(a)        ((((in_addr_t)(a)) & 0xf0000000) == 0xe0000000)/usr/include/netinet/in.h:#define    IN_EXPERIMENTAL(a)    ((((in_addr_t)(a)) & 0xe0000000) == 0xe0000000)/usr/include/netinet/in.h:#define    IN_BADCLASS(a)        ((((in_addr_t)(a)) & 0xf0000000) == 0xf0000000)/usr/include/netinet/in.h:#define    INADDR_ANY        ((in_addr_t) 0x00000000)/usr/include/netinet/in.h:#define    INADDR_BROADCAST    ((in_addr_t) 0xffffffff)/usr/include/netinet/in.h:#define    INADDR_NONE        ((in_addr_t) 0xffffffff)/usr/include/netinet/in.h:# define INADDR_LOOPBACK    ((in_addr_t) 0x7f000001) /* Inet 127.0.0.1.  *//usr/include/netinet/in.h:#define INADDR_UNSPEC_GROUP    ((in_addr_t) 0xe0000000) /* 224.0.0.0 *//usr/include/netinet/in.h:#define INADDR_ALLHOSTS_GROUP    ((in_addr_t) 0xe0000001) /* 224.0.0.1 *//usr/include/netinet/in.h:#define INADDR_ALLRTRS_GROUP    ((in_addr_t) 0xe0000002) /* 224.0.0.2 *//usr/include/netinet/in.h:#define INADDR_MAX_LOCAL_GROUP  ((in_addr_t) 0xe00000ff) /* 224.0.0.255 */

3，過濾，grep "in_addr_t" /usr/include/*/*.h | grep "typedef"  

用typedef過濾一次，或者用define等關鍵字， 這種資料類型肯定是標準類型的別名定義，出現下面這條資料，他是uint32_t這個資料類型的別名

/usr/include/netinet/in.h:typedef uint32_t in_addr_t;

4，下一步，肯定是找uint32_t的定義類型 grep "uint32_t" /usr/include/*/*.h | grep "typedef"，出現結果:

/usr/include/drm/drm.h:typedef uint32_t __u32;/usr/include/netinet/in.h:typedef uint32_t in_addr_t;

這不是我想要的

5，grep "uint32_t" /usr/include/*.h | grep "typedef"

/usr/include/elf.h:typedef uint32_t Elf32_Word;/usr/include/elf.h:typedef uint32_t Elf64_Word;/usr/include/elf.h:typedef uint32_t Elf32_Addr;/usr/include/elf.h:typedef uint32_t Elf32_Off;/usr/include/stdint.h:typedef unsigned int        uint32_t;

這才是我想要的, uint32_t其實是unsigned int類型

6，grep -n "uint32_t" /usr/include/stdint.h 查出資料定義所在的行號

50:#ifndef __uint32_t_defined51:typedef unsigned int        uint32_t;52:# define __uint32_t_defined