1、使用dd命令读写数据。
[[email protected] ~]# dd --help 用法：dd [操作数] ... 或：dd 选项 Copy a file, converting and formatting according to the operands. bs=BYTES read and write up to BYTES bytes at a time cbs=BYTES convert BYTES bytes at a time conv=CONVS convert the file as per the comma separated symbol list count=N copy only N input blocks ibs=BYTES read up to BYTES bytes at a time (default: 512) if=FILE read from FILE instead of stdin iflag=FLAGS read as per the comma separated symbol list obs=BYTES write BYTES bytes at a time (default: 512) of=FILE write to FILE instead of stdout oflag=FLAGS write as per the comma separated symbol list seek=N skip N obs-sized blocks at start of output skip=N skip N ibs-sized blocks at start of input status=LEVEL The LEVEL of information to print to stderr; 'none' suppresses everything but error messages, 'noxfer' suppresses the final transfer statistics, 'progress' shows periodic transfer statistics N and BYTES may be followed by the following multiplicative suffixes: c =1, w =2, b =512, kB =1000, K =1024, MB =1000*1000, M =1024*1024, xM =M GB =1000*1000*1000, G =1024*1024*1024, and so on for T, P, E, Z, Y. Each CONV symbol may be: ascii from EBCDIC to ASCII ebcdic from ASCII to EBCDIC ibm from ASCII to alternate EBCDIC block pad newline-terminated records with spaces to cbs-size unblock replace trailing spaces in cbs-size records with newline lcase change upper case to lower case ucase change lower case to upper case sparse try to seek rather than write the output for NUL input blocks swab swap every pair of input bytes sync pad every input block with NULs to ibs-size; when used with block or unblock, pad with spaces rather than NULs excl fail if the output file already exists nocreat do not create the output file notrunc 不截断输出文件 noerror 读取数据发生错误后仍然继续 fdatasync 结束前将输出文件数据写入磁盘 fsync 类似上面，但是元数据也一同写入 FLAG 符号可以是： append 追加模式(仅对输出有意义；隐含了conv=notrunc) direct 使用直接I/O 存取模式 directory 除非是目录，否则 directory 失败 dsync 使用同步I/O 存取模式 sync 与上者类似，但同时也对元数据生效 fullblock 为输入积累完整块(仅iflag) nonblock 使用无阻塞I/O 存取模式 noatime 不更新存取时间 nocache 丢弃缓存数据 noctty 不根据文件指派控制终端 nofollow 不跟随链接文件 count_bytes treat 'count=N' as a byte count (iflag only) skip_bytes treat 'skip=N' as a byte count (iflag only) seek_bytes treat 'seek=N' as a byte count (oflag only) Sending a USR1 signal to a running 'dd' process makes it print I/O statistics to standard error and then resume copying. $ dd if=/dev/zero of=/dev/null& pid=$! $ kill -USR1 $pid; sleep 1; kill $pid 18335302+0 records in 18335302+0 records out 9387674624 bytes (9.4 GB) copied, 34.6279 seconds, 271 MB/s 示例一、 [ ~]# dd
