函数定义
int access(const char * pathname, int mode)
作用：用以检查是否可以对指定的文件执行某种操作
参数
- pathname: 需要检测的文件路径名
- mode: 需要测试的操作模式
mode说明：
#define F_OK 0 /* test for existence of file */
#define X_OK (1<<0) /* test for execute or search permission */
#define W_OK (1<<1) /* test for write permission */
#define R_OK (1<<2) /* test for read permission */
#if !defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE)
/*
* Extended access functions.
* Note that we depend on these matching the definitions in sys/kauth.h,
* but with the bits shifted left by 8.
*/
#define _READ_OK (1<<9) /* read file data / read directory */
#define _WRITE_OK (1<<10) /* write file data / add file to directory */
#define _EXECUTE_OK (1<<11) /* execute file / search in directory*/
#define _DELETE_OK (1<<12) /* delete file / delete directory */
#define _APPEND_OK (1<<13) /* append to file / add subdirectory to directory */
#define _RMFILE_OK (1<<14) /* - / remove file from directory */
#define _RATTR_OK (1<<15) /* read basic attributes */
#define _WATTR_OK (1<<16) /* write basic attributes */
#define _REXT_OK (1<<17) /* read extended attributes */
#define _WEXT_OK (1<<18) /* write extended attributes */
#define _RPERM_OK (1<<19) /* read permissions */
#define _WPERM_OK (1<<20) /* write permissions */
#define _CHOWN_OK (1<<21) /* change ownership */
#define _ACCESS_EXTENDED_MASK (_READ_OK | _WRITE_OK | _EXECUTE_OK | \
_DELETE_OK | _APPEND_OK | \
_RMFILE_OK | _REXT_OK | \
_WEXT_OK | _RATTR_OK | _WATTR_OK | _RPERM_OK | \
_WPERM_OK | _CHOWN_OK)
#endif
返回值
成功执行时，返回0。失败返回-1
函数实例
int test()
{
if(access("test.txt", R_OK)==0) printf("READ OK\n");
if(access("test.txt", W_OK)==0) printf("WRITE OK\n");
if(access("test.txt", X_OK)==0) printf("EXEC OK\n");
if(access("test.txt", F_OK)==0) printf("File exist\n");
}
