20135306黄韧 ——第十章续

第十章（续）

编译运行代码

echostate

检验在命令行中输入命令时是否可见，如果可见，返回echo is on , since its bit is 1

#include<stdio.h>
#include<stdlib.h>
#include<termios.h>

int main()
{
struct termios info;
int rv;

rv = tcgetattr( 0, &info ); /* read values from driver  */

if ( rv == -1 ){
perror( "tcgetattr");
exit(1);
}
if ( info.c_lflag & ECHO )
printf(" echo is on , since its bit is 1
");
else
printf(" echo is OFF, since its bit is 0
");

		return 0;
}

 

fileinfo

查看文件信息。

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>

void show_stat_info(char *, struct stat *);

int main(int argc, char *argv[])
{
struct stat info;

if (argc>1)
	{
	
if( stat(argv[1], &info) != -1 ){
show_stat_info( argv[1], &info );
return 0;
}
else
perror(argv[1]);  
	}
return 1;
}
void show_stat_info(char *fname, struct stat *buf)
{
printf("   mode: %o
", buf->st_mode); 
printf("  links: %d
", buf->st_nlink);
printf("   user: %d
", buf->st_uid);  
printf("  group: %d
", buf->st_gid);  
printf("   size: %d
", (int)buf->st_size); 
printf("modtime: %d
", (int)buf->st_mtime);
printf("   name: %s
", fname );   
}

• finfo_buffer — 返回一个字符串缓冲区的信息
• finfo_close — 关闭 fileinfo 资源
• finfo_file — 返回一个文件的信息
• finfo_open — 创建一个 fileinfo 资源
• finfo_set_flags — 设置 libmagic 配置选项
• mime_content_type — 检测文件的 MIME 类型（已废弃）

filesize

计算文件的字节数大小。

#include <stdio.h>
#include <sys/stat.h>

int main()
{
	struct stat infobuf;   

	if ( stat( "/etc/passwd", &infobuf) == -1 )
		perror("/etc/passwd");
	else
		printf(" The size of /etc/passwd is %d
", infobuf.st_size );
}

filesize() 函数返回指定文件的大小

若成功，则返回文件大小的字节数。若失败，则返回 false 并生成一条 E_WARNING 级的错误

语法

filesize(filename)

参数	描述
filename	必需。规定要检查的文件。

ls1

显示当前目录下的文件。

#include	<stdio.h>
#include	<sys/types.h>
#include	<dirent.h>

void do_ls(char []);

int main(int argc, char *argv[])
{
	if ( argc == 1 )
		do_ls( "." );
	else
		while ( --argc ){
			printf("%s:
", *++argv );
			do_ls( *argv );
		}

	return 0;
}

void do_ls( char dirname[] )
{
	DIR		*dir_ptr;		
	struct dirent	*direntp;		

	if ( ( dir_ptr = opendir( dirname ) ) == NULL )
		fprintf(stderr,"ls1: cannot open %s
", dirname);
	else
	{
		while ( ( direntp = readdir( dir_ptr ) ) != NULL )
			printf("%s
", direntp->d_name );
		closedir(dir_ptr);
	}
}

 

ls2

查看文件的详细信息，比如用户名，群组名，大小，创建时间，读写权限等。

#include	<stdio.h>
#include<string.h>
#include	<sys/types.h>
#include	<dirent.h>
#include	<sys/stat.h>

void do_ls(char[]);
void dostat(char *);
void show_file_info( char *, struct stat *);
void mode_to_letters( int , char [] );
char *uid_to_name( uid_t );
char *gid_to_name( gid_t );

int main(int argc, char *argv[])
{
	if ( argc == 1 )
		do_ls( "." );
	else
		while ( --argc ){
			printf("%s:
", *++argv );
			do_ls( *argv );
		}

	return 0;
}

void do_ls( char dirname[] )
{
	DIR		*dir_ptr;		
	struct dirent	*direntp;		

	if ( ( dir_ptr = opendir( dirname ) ) == NULL )
		fprintf(stderr,"ls1: cannot open %s
", dirname);
	else
	{
		while ( ( direntp = readdir( dir_ptr ) ) != NULL )
			dostat( direntp->d_name );
		closedir(dir_ptr);
	}
}

void dostat( char *filename )
{
	struct stat info;

	if ( stat(filename, &info) == -1 )		
		perror( filename );			
	else					
		show_file_info( filename, &info );
}

void show_file_info( char *filename, struct stat *info_p )
{
	char	*uid_to_name(), *ctime(), *gid_to_name(), *filemode();
	void	mode_to_letters();
charmodestr[11];

	mode_to_letters( info_p->st_mode, modestr );

	printf( "%s", modestr );
	printf( "%4d "  , (int) info_p->st_nlink);	
	printf( "%-8s " , uid_to_name(info_p->st_uid) );
	printf( "%-8s " , gid_to_name(info_p->st_gid) );
	printf( "%8ld " , (long)info_p->st_size);
	printf( "%.12s ", 4+ctime(&info_p->st_mtime));
	printf( "%s
"  , filename );

}

void mode_to_letters( int mode, char str[] )
{
strcpy( str, "----------" );   

if ( S_ISDIR(mode) )  str[0] = 'd';
if ( S_ISCHR(mode) )  str[0] = 'c';
if ( S_ISBLK(mode) )  str[0] = 'b';

if ( mode & S_IRUSR ) str[1] = 'r';
if ( mode & S_IWUSR ) str[2] = 'w';
if ( mode & S_IXUSR ) str[3] = 'x';

if ( mode & S_IRGRP ) str[4] = 'r';
if ( mode & S_IWGRP ) str[5] = 'w';
if ( mode & S_IXGRP ) str[6] = 'x';

if ( mode & S_IROTH ) str[7] = 'r';
if ( mode & S_IWOTH ) str[8] = 'w';
if ( mode & S_IXOTH ) str[9] = 'x';
}

#include	<pwd.h>

char *uid_to_name( uid_t uid )
{
	struct	passwd *getpwuid(), *pw_ptr;
	static  char numstr[10];

	if ( ( pw_ptr = getpwuid( uid ) ) == NULL ){
		sprintf(numstr,"%d", uid);
		return numstr;
	}
	else
		return pw_ptr->pw_name ;
}

#include	<grp.h>

char *gid_to_name( gid_t gid )
{
	struct group *getgrgid(), *grp_ptr;
	static  char numstr[10];

	if ( ( grp_ptr = getgrgid(gid) ) == NULL ){
		sprintf(numstr,"%d", gid);
		return numstr;
	}
	else
		return grp_ptr->gr_name;
}

setecho

设置在命令行中输入命令时是否可见，如果可见，输入setecho yes;如果设置为不可见，输入setecho no。

#include<stdio.h>
#include 		<stdlib.h>
#include<termios.h>

#define  oops(s,x) { perror(s); exit(x); }

int main(int argc, char *argv[])
{
struct termios info;

if ( argc == 1 ) 
		exit(0);

if ( tcgetattr(0,&info) == -1 )  /* get attribs   */
			oops("tcgettattr", 1);

if ( argv[1][0] == 'y' )
info.c_lflag |= ECHO ;  /* turn on bit*/
else
info.c_lflag &= ~ECHO ; /* turn off bit   */

if ( tcsetattr(0,TCSANOW,&info) == -1 ) /* set attribs*/
   oops("tcsetattr",2);
	
		return 0;
}

 

spwd

显示当前所在目录。

#include	<stdio.h>
#include<stdlib.h>
#include<string.h>
#include	<sys/types.h>
#include	<sys/stat.h>
#include	<dirent.h>

ino_t	get_inode(char *);
voidprintpathto(ino_t);
voidinum_to_name(ino_t , char *, int );

int main()
{
	printpathto( get_inode( "." ) );	
	putchar('
');				
	return 0;
}

void printpathto( ino_t this_inode )
{
	ino_t	my_inode ;
	char	its_name[BUFSIZ];

	if ( get_inode("..") != this_inode )
	{
		chdir( ".." );				

		inum_to_name(this_inode,its_name,BUFSIZ);

		my_inode = get_inode( "." );		
		printpathto( my_inode );		
		printf("/%s", its_name );		
							
	}
}

void inum_to_name(ino_t inode_to_find , char *namebuf, int buflen)
{
	DIR		*dir_ptr;		
	struct dirent	*direntp;		

	dir_ptr = opendir( "." );
	if ( dir_ptr == NULL ){
		perror( "." );
		exit(1);
	}


	while ( ( direntp = readdir( dir_ptr ) ) != NULL )
		if ( direntp->d_ino == inode_to_find )
		{
			strncpy( namebuf, direntp->d_name, buflen);
			namebuf[buflen-1] = '';   
			closedir( dir_ptr );
			return;
		}
	fprintf(stderr, "error looking for inum %d
", (int) inode_to_find);
	exit(1);
}

ino_t get_inode( char *fname )
{
	struct stat info;

	if ( stat( fname , &info ) == -1 ){
		fprintf(stderr, "Cannot stat ");
		perror(fname);
		exit(1);
	}
	return info.st_ino;
}

 

testioctl

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>

int main()
{
	struct winsize size;
	if( isatty(STDOUT_FILENO) == 0)
		exit(1);
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &size) < 0) {
		perror("ioctl TIOCGWINSZ error");
		exit(1);
	}

	printf("%d rows %d columns
", size.ws_row, size.ws_col);
	return 0;
}

 

who1

从UTMP_FILE文件中读取想要的信息到存储器中，然后再用标准输出函数打印到屏幕上，最后关闭文件。

#include	<stdio.h>
#include<stdlib.h>
#include	<utmp.h>
#include	<fcntl.h>
#include	<unistd.h>

#define	SHOWHOST	

int show_info( struct utmp *utbufp )
{
	printf("%-8.8s", utbufp->ut_name);	
	printf(" ");				
	printf("%-8.8s", utbufp->ut_line);	
	printf(" ");				
	printf("%10ld", utbufp->ut_time);	
	printf(" ");				
#ifdef	SHOWHOST
	printf("(%s)", utbufp->ut_host);	
#endif
	printf("
");				

	return 0;
}
int main()
{
	struct utmp	 current_record;	
	int		utmpfd;		
	int		reclen = sizeof(current_record);

	if ( (utmpfd = open(UTMP_FILE, O_RDONLY)) == -1 ){
		perror( UTMP_FILE );	
		exit(1);
	}
	while ( read(utmpfd, &current_record, reclen) == reclen )
		show_info(&current_record);
	close(utmpfd);
	return 0;			
}

who2

#include	<stdio.h>
#include<stdlib.h>
#include	<utmp.h>
#include	<fcntl.h>
#include	<unistd.h>

#define	SHOWHOST	

int show_info( struct utmp *utbufp )
{
	printf("%-8.8s", utbufp->ut_name);	
	printf(" ");				
	printf("%-8.8s", utbufp->ut_line);	
	printf(" ");				
	printf("%10ld", utbufp->ut_time);	
	printf(" ");				
#ifdef	SHOWHOST
	printf("(%s)", utbufp->ut_host);	
#endif
	printf("
");				

	return 0;
}
int main()
{
	struct utmp	 current_record;	
	int		utmpfd;		
	int		reclen = sizeof(current_record);

	if ( (utmpfd = open(UTMP_FILE, O_RDONLY)) == -1 ){
		perror( UTMP_FILE );	
		exit(1);
	}
	while ( read(utmpfd, &current_record, reclen) == reclen )
		show_info(&current_record);
	close(utmpfd);
	return 0;			
}

 

 

参考资料

1. 教材：第十章，详细学习指导：http://group.cnblogs.com/topic/73069.html
2. 课程资料：https://www.shiyanlou.com/courses/413 实验十，课程邀请码：W7FQKW4Y
   
3. 教材中代码运行、思考一下，读代码的学习方法：http://www.cnblogs.com/rocedu/p/4837092.html。