One. File manipulation functions
1.stat function
1.1 stat records the information file
1.2 st_mode by a 16-bit binary number, as shown below:
The following figure shows the various octal file type will be obtained st_mode & 0170000 file type to a file is not determined normal file:
struct stat st；
stat("123.txt"，&st);
if（(st.st_mode&S_IFMT)==S_IFREG）
{
printf ( "This is a regular file");
}
1.3 Calculation type file permissions follows:
Further reference may be: https: //blog.csdn.net/astrotycoon/article/details/8679676
2.lstat function
3.chmod
4.chown
uid and gid can be viewed in vi / etc / passwd in
5.truncate
6.link
7.rename
8.dup dup2
To copy a file descriptor
Prototype:
The minimum 1.dup oldfd copy file descriptors available, and returns
Example program: ret write and the file descriptor fd may by conventional a.txt data file, and the file pointer is not restored.
2.dup2 will oldfd copied as newfd
The sample program: The original "english.txt" copy of the file descriptor fd is fd1, namely a.txt file descriptors, and write data to a.txt
9.fcntl
Get file status when an incoming F_GETFL cmd, arg = 0;
An incoming file status F_SETFL cmd, arg = flag;
II. Directory manipulation functions
1.chdir 和 getcwd
2.mkdir 和 rmdir
3.opendir
4.readdir
//递归读取子目录并计算普通文件个数
#include<stdio.h> #include<stdlib.h> #include<dirent> int getFileNum(const char *filename) { DIR *dir=NULL; dir=opendir(filename); struct dirent* ptr=NULL; if(dir==NULL) { perror("opendir"); exit(1); } char path[1024]={0}; while((ptr=readdir(dir))!=null) { //过滤.和.. if(strcmp(ptr->d_name,".")==0||strcmp(ptr->d_name,"..")==0) { continue; } //如果是目录 if(ptr->d_type==DT_DIR) { sprintf(path,"%s%s",filename,ptr->d_name); //递归读目录 total+=getFileNum(path); } //如果是普通文件 if(ptr->d_type==DT_REG) { total++; } } closedir(dir); return total; } int main(int argc,char* argv[]) { int total=getFileNum(argv[1]); printf("%s has file numbers %d",argv[1],total); return 0; }
5.closedir
