Linux I/O篇

Test1:

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>int main(int argc,char *argv[]){        char buf[128];        memset(buf,0x00,sizeof(buf));        int len = read(STDIN_FILENO,buf,sizeof(buf));        write(STDOUT_FILENO,buf,len);        return 0;}

Test2:

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/stat.h>#include <sys/types.h>#include <fcntl.h>#include <string.h>int main(int argc,char *argv[]){        if(argc < 3)        {                printf("inupt error!");//了解printf刷新缓冲的机制                sleep(10);                return 0;        }        int len;        int fd_src,fd_dest;        fd_src = open(argv[1],O_RDONLY);        fd_dest = open(argv[2],O_CREAT|O_WRONLY|O_TRUNC,0777);        char buf[1024];        while(len = read(fd_src,buf,sizeof(buf)))        {                write(fd_dest,buf,len);        }        close(fd_src);        close(fd_dest);        printf("success!@!\n");        return 0;}

文件描述符的一些信息

lili@lili-linux:~$ ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 3823
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 3823
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

lili@lili-linux:~$ cat /proc/sys/fs/file-max
97384

lili@lili-linux:~$ cat /usr/include/asm-generic/errno-base.h#ifndef _ASM_GENERIC_ERRNO_BASE_H#define _ASM_GENERIC_ERRNO_BASE_H#define EPERM            1      /* Operation not permitted */#define ENOENT           2      /* No such file or directory */#define ESRCH            3      /* No such process */#define EINTR            4      /* Interrupted system call */#define EIO              5      /* I/O error */#define ENXIO            6      /* No such device or address */#define E2BIG            7      /* Argument list too long */#define ENOEXEC          8      /* Exec format error */#define EBADF            9      /* Bad file number */#define ECHILD          10      /* No child processes */#define EAGAIN          11      /* Try again */#define ENOMEM          12      /* Out of memory */#define EACCES          13      /* Permission denied */#define EFAULT          14      /* Bad address */#define ENOTBLK         15      /* Block device required */#define EBUSY           16      /* Device or resource busy */#define EEXIST          17      /* File exists */#define EXDEV           18      /* Cross-device link */#define ENODEV          19      /* No such device */#define ENOTDIR         20      /* Not a directory */#define EISDIR          21      /* Is a directory */#define EINVAL          22      /* Invalid argument */#define ENFILE          23      /* File table overflow */#define EMFILE          24      /* Too many open files */#define ENOTTY          25      /* Not a typewriter */#define ETXTBSY         26      /* Text file busy */#define EFBIG           27      /* File too large */#define ENOSPC          28      /* No space left on device */#define ESPIPE          29      /* Illegal seek */#define EROFS           30      /* Read-only file system */#define EMLINK          31      /* Too many links */#define EPIPE           32      /* Broken pipe */#define EDOM            33      /* Math argument out of domain of func */#define ERANGE          34      /* Math result not representable */