stat
查詢檔案大小、建立時間、修改時間、型態...
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
int stat(const char *pathname, struct stat *statbuf);
int lstat(const char *pathname, struct stat *statbuf);
struct stat {
dev_t st_dev; /* ID of device containing file */
ino_t st_ino; /* Inode number */
mode_t st_mode; /* File type and mode */
nlink_t st_nlink; /* Number of hard links */
uid_t st_uid; /* User ID of owner */
gid_t st_gid; /* Group ID of owner */
dev_t st_rdev; /* Device ID (if special file) */
off_t st_size; /* Total size, in bytes */
blksize_t st_blksize; /* Block size for filesystem I/O */
blkcnt_t st_blocks; /* Number of 512B blocks allocated */
/* Since Linux 2.6, the kernel supports nanosecond
precision for the following timestamp fields.
For the details before Linux 2.6, see NOTES. */
struct timespec st_atim; /* Time of last access */
struct timespec st_mtim; /* Time of last modification */
struct timespec st_ctim; /* Time of last status change */
#define st_atime st_atim.tv_sec /* Backward compatibility */
#define st_mtime st_mtim.tv_sec
#define st_ctime st_ctim.tv_sec
};
一般用法範例:
struct stat st;
memset(&st, '\0', sizeof(struct stat));
if(stat("/filepath", &st))
return -1;
if(S_ISDIR(st.st_mode)) { //判斷是否為目錄
// is dir
}
if(S_ISREG(st.st_mode)) { //判斷是否為檔案
// is file
}
判斷 link 要改用 lstat:
struct stat st;
memset(&st, '\0', sizeof(struct stat));
if(lstat("/filepath", &st))
return -1;
if(S_ISLNK(st.st_mode)) { //判斷题否為link
// is link
}
access
判斷檔案是否存在
#include <unistd.h>
int access(const char *pathname, int mode);
用法:
if(!access("/filepath", F_OK)) {
// 回傳0,表示檔案存在
} else {
// 回傳-1, 表示檔案不存在
}
system
system("echo testString"); // 呼叫外部程式
用 system 執行可直接判斷回傳值 (也可用popen呼叫)
回傳 0,在 popen 是回傳 0
回傳 256,在 popen 是回傳 1
回傳 65280,在 popen 是回傳 -1
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