{"id":1683,"date":"2019-04-28T04:57:53","date_gmt":"2019-04-27T20:57:53","guid":{"rendered":"https:\/\/www.xiaobo.li\/?p=1683"},"modified":"2019-04-28T04:58:47","modified_gmt":"2019-04-27T20:58:47","slug":"linux-dd","status":"publish","type":"post","link":"https:\/\/www.xiaobo.li\/notes\/archives\/1683","title":{"rendered":"Linux dd"},"content":{"rendered":"\n

\u4e00\u3001dd\u547d\u4ee4\u7684\u89e3\u91ca<\/h2>\n\n\n\n

dd\uff1a\u7528\u6307\u5b9a\u5927\u5c0f\u7684\u5757\u62f7\u8d1d\u4e00\u4e2a\u6587\u4ef6\uff0c\u5e76\u5728\u62f7\u8d1d\u7684\u540c\u65f6\u8fdb\u884c\u6307\u5b9a\u7684\u8f6c\u6362\u3002<\/p>\n\n\n\n

\u6ce8\u610f\uff1a\u6307\u5b9a\u6570\u5b57\u7684\u5730\u65b9\u82e5\u4ee5\u4e0b\u5217\u5b57\u7b26\u7ed3\u5c3e\uff0c\u5219\u4e58\u4ee5\u76f8\u5e94\u7684\u6570\u5b57\uff1ab=512\uff1bc=1\uff1bk=1024\uff1bw=2<\/p>\n\n\n\n

\u53c2\u6570\u6ce8\u91ca\uff1a<\/strong><\/p>\n\n\n\n

1. if=\u6587\u4ef6\u540d\uff1a\u8f93\u5165\u6587\u4ef6\u540d\uff0c\u7f3a\u7701\u4e3a\u6807\u51c6\u8f93\u5165\u3002\u5373\u6307\u5b9a\u6e90\u6587\u4ef6\u3002< if=input file ><\/p>\n\n\n\n

2. of=\u6587\u4ef6\u540d\uff1a\u8f93\u51fa\u6587\u4ef6\u540d\uff0c\u7f3a\u7701\u4e3a\u6807\u51c6\u8f93\u51fa\u3002\u5373\u6307\u5b9a\u76ee\u7684\u6587\u4ef6\u3002< of=output file ><\/p>\n\n\n\n

3. ibs=bytes\uff1a\u4e00\u6b21\u8bfb\u5165bytes\u4e2a\u5b57\u8282\uff0c\u5373\u6307\u5b9a\u4e00\u4e2a\u5757\u5927\u5c0f\u4e3abytes\u4e2a\u5b57\u8282\u3002<\/p>\n\n\n\n

    obs=bytes\uff1a\u4e00\u6b21\u8f93\u51fabytes\u4e2a\u5b57\u8282\uff0c\u5373\u6307\u5b9a\u4e00\u4e2a\u5757\u5927\u5c0f\u4e3abytes\u4e2a\u5b57\u8282\u3002<\/p>\n\n\n\n

    bs=bytes\uff1a\u540c\u65f6\u8bbe\u7f6e\u8bfb\u5165\/\u8f93\u51fa\u7684\u5757\u5927\u5c0f\u4e3abytes\u4e2a\u5b57\u8282\u3002<\/p>\n\n\n\n

4. cbs=bytes\uff1a\u4e00\u6b21\u8f6c\u6362bytes\u4e2a\u5b57\u8282\uff0c\u5373\u6307\u5b9a\u8f6c\u6362\u7f13\u51b2\u533a\u5927\u5c0f\u3002<\/p>\n\n\n\n

5. skip=blocks\uff1a\u4ece\u8f93\u5165\u6587\u4ef6\u5f00\u5934\u8df3\u8fc7blocks\u4e2a\u5757\u540e\u518d\u5f00\u59cb\u590d\u5236\u3002<\/p>\n\n\n\n

6. seek=blocks\uff1a\u4ece\u8f93\u51fa\u6587\u4ef6\u5f00\u5934\u8df3\u8fc7blocks\u4e2a\u5757\u540e\u518d\u5f00\u59cb\u590d\u5236\u3002<\/p>\n\n\n\n

\u6ce8\u610f\uff1a\u901a\u5e38\u53ea\u7528\u5f53\u8f93\u51fa\u6587\u4ef6\u662f\u78c1\u76d8\u6216\u78c1\u5e26\u65f6\u624d\u6709\u6548\uff0c\u5373\u5907\u4efd\u5230\u78c1\u76d8\u6216\u78c1\u5e26\u65f6\u624d\u6709\u6548\u3002<\/p>\n\n\n\n

7. count=blocks\uff1a\u4ec5\u62f7\u8d1dblocks\u4e2a\u5757\uff0c\u5757\u5927\u5c0f\u7b49\u4e8eibs\u6307\u5b9a\u7684\u5b57\u8282\u6570\u3002<\/p>\n\n\n\n

8. conv=conversion\uff1a\u7528\u6307\u5b9a\u7684\u53c2\u6570\u8f6c\u6362\u6587\u4ef6\u3002<\/p>\n\n\n\n

    ascii\uff1a\u8f6c\u6362ebcdic\u4e3aascii<\/p>\n\n\n\n

     ebcdic\uff1a\u8f6c\u6362ascii\u4e3aebcdic<\/p>\n\n\n\n

    ibm\uff1a\u8f6c\u6362ascii\u4e3aalternate ebcdic<\/p>\n\n\n\n

    block\uff1a\u628a\u6bcf\u4e00\u884c\u8f6c\u6362\u4e3a\u957f\u5ea6\u4e3acbs\uff0c\u4e0d\u8db3\u90e8\u5206\u7528\u7a7a\u683c\u586b\u5145<\/p>\n\n\n\n

    unblock\uff1a\u4f7f\u6bcf\u4e00\u884c\u7684\u957f\u5ea6\u90fd\u4e3acbs\uff0c\u4e0d\u8db3\u90e8\u5206\u7528\u7a7a\u683c\u586b\u5145<\/p>\n\n\n\n

    lcase\uff1a\u628a\u5927\u5199\u5b57\u7b26\u8f6c\u6362\u4e3a\u5c0f\u5199\u5b57\u7b26<\/p>\n\n\n\n

    ucase\uff1a\u628a\u5c0f\u5199\u5b57\u7b26\u8f6c\u6362\u4e3a\u5927\u5199\u5b57\u7b26<\/p>\n\n\n\n

    swab\uff1a\u4ea4\u6362\u8f93\u5165\u7684\u6bcf\u5bf9\u5b57\u8282<\/p>\n\n\n\n

     noerror\uff1a\u51fa\u9519\u65f6\u4e0d\u505c\u6b62<\/p>\n\n\n\n

     notrunc\uff1a\u4e0d\u622a\u77ed\u8f93\u51fa\u6587\u4ef6<\/p>\n\n\n\n

    sync\uff1a\u5c06\u6bcf\u4e2a\u8f93\u5165\u5757\u586b\u5145\u5230ibs\u4e2a\u5b57\u8282\uff0c\u4e0d\u8db3\u90e8\u5206\u7528\u7a7a\uff08NUL\uff09\u5b57\u7b26\u8865\u9f50\u3002<\/p>\n\n\n\n

\u4e8c\u3001dd\u5e94\u7528\u5b9e\u4f8b<\/h1>\n\n\n\n

1.<\/strong>\u5c06\u672c\u5730\u7684<\/strong>\/dev\/hdb<\/strong>\u6574\u76d8\u5907\u4efd\u5230<\/strong>\/dev\/hdd<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/hdb of=\/dev\/hdd<\/p>\n\n\n\n

2.<\/strong>\u5c06<\/strong>\/dev\/hdb<\/strong>\u5168\u76d8\u6570\u636e\u5907\u4efd\u5230\u6307\u5b9a\u8def\u5f84\u7684<\/strong>image<\/strong>\u6587\u4ef6<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/hdb of=\/root\/image<\/p>\n\n\n\n

3.<\/strong>\u5c06\u5907\u4efd\u6587\u4ef6\u6062\u590d\u5230\u6307\u5b9a\u76d8<\/strong><\/p>\n\n\n\n

#dd if=\/root\/image of=\/dev\/hdb<\/p>\n\n\n\n

4.<\/strong>\u5907\u4efd<\/strong>\/dev\/hdb<\/strong>\u5168\u76d8\u6570\u636e\uff0c\u5e76\u5229\u7528<\/strong>gzip<\/strong>\u5de5\u5177\u8fdb\u884c\u538b\u7f29\uff0c\u4fdd\u5b58\u5230\u6307\u5b9a\u8def\u5f84<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/hdb | gzip > \/root\/image.gz<\/p>\n\n\n\n

5.<\/strong>\u5c06\u538b\u7f29\u7684\u5907\u4efd\u6587\u4ef6\u6062\u590d\u5230\u6307\u5b9a\u76d8<\/strong><\/p>\n\n\n\n

#gzip -dc \/root\/image.gz | dd of=\/dev\/hdb<\/p>\n\n\n\n

6.<\/strong>\u5907\u4efd\u4e0e\u6062\u590d<\/strong>MBR<\/strong><\/p>\n\n\n\n

\u5907\u4efd\u78c1\u76d8\u5f00\u59cb\u7684512\u4e2a\u5b57\u8282\u5927\u5c0f\u7684MBR\u4fe1\u606f\u5230\u6307\u5b9a\u6587\u4ef6\uff1a<\/p>\n\n\n\n

#dd if=\/dev\/hda of=\/root\/image count=1 bs=512<\/p>\n\n\n\n

   count=1\u6307\u4ec5\u62f7\u8d1d\u4e00\u4e2a\u5757\uff1bbs=512\u6307\u5757\u5927\u5c0f\u4e3a512\u4e2a\u5b57\u8282\u3002<\/p>\n\n\n\n

\u6062\u590d\uff1a<\/p>\n\n\n\n

#dd if=\/root\/image of=\/dev\/had<\/p>\n\n\n\n

\u5c06\u5907\u4efd\u7684MBR\u4fe1\u606f\u5199\u5230\u78c1\u76d8\u5f00\u59cb\u90e8\u5206<\/p>\n\n\n\n

7.<\/strong>\u5907\u4efd\u8f6f\u76d8<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/fd0 of=disk.img count=1 bs=1440k (\u5373\u5757\u5927\u5c0f\u4e3a1.44M)<\/p>\n\n\n\n

8.<\/strong>\u62f7\u8d1d\u5185\u5b58\u5185\u5bb9\u5230\u786c\u76d8<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/mem of=\/root\/mem.bin bs=1024 (\u6307\u5b9a\u5757\u5927\u5c0f\u4e3a1k)  <\/p>\n\n\n\n

9.<\/strong>\u62f7\u8d1d\u5149\u76d8\u5185\u5bb9\u5230\u6307\u5b9a\u6587\u4ef6\u5939\uff0c\u5e76\u4fdd\u5b58\u4e3a<\/strong>cd.iso<\/strong>\u6587\u4ef6<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/cdrom(hdc) of=\/root\/cd.iso<\/p>\n\n\n\n

10.<\/strong>\u589e\u52a0<\/strong>swap<\/strong>\u5206\u533a\u6587\u4ef6\u5927\u5c0f<\/strong><\/p>\n\n\n\n

\u7b2c\u4e00\u6b65\uff1a\u521b\u5efa\u4e00\u4e2a\u5927\u5c0f\u4e3a256M\u7684\u6587\u4ef6\uff1a<\/p>\n\n\n\n

#dd if=\/dev\/zero of=\/swapfile bs=1024 count=262144<\/p>\n\n\n\n

\u7b2c\u4e8c\u6b65\uff1a\u628a\u8fd9\u4e2a\u6587\u4ef6\u53d8\u6210swap\u6587\u4ef6\uff1a<\/p>\n\n\n\n

#mkswap \/swapfile<\/p>\n\n\n\n

\u7b2c\u4e09\u6b65\uff1a\u542f\u7528\u8fd9\u4e2aswap\u6587\u4ef6\uff1a<\/p>\n\n\n\n

#swapon \/swapfile<\/p>\n\n\n\n

\u7b2c\u56db\u6b65\uff1a\u7f16\u8f91\/etc\/fstab\u6587\u4ef6\uff0c\u4f7f\u5728\u6bcf\u6b21\u5f00\u673a\u65f6\u81ea\u52a8\u52a0\u8f7dswap\u6587\u4ef6\uff1a<\/p>\n\n\n\n

\/swapfile    swap    swap    default   0 0<\/p>\n\n\n\n

11.<\/strong>\u9500\u6bc1\u78c1\u76d8\u6570\u636e<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/urandom of=\/dev\/hda1<\/p>\n\n\n\n

\u6ce8\u610f\uff1a\u5229\u7528\u968f\u673a\u7684\u6570\u636e\u586b\u5145\u786c\u76d8\uff0c\u5728\u67d0\u4e9b\u5fc5\u8981\u7684\u573a\u5408\u53ef\u4ee5\u7528\u6765\u9500\u6bc1\u6570\u636e\u3002<\/p>\n\n\n\n

12.<\/strong>\u6d4b\u8bd5\u786c\u76d8\u7684\u8bfb\u5199\u901f\u5ea6<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/zero bs=1024 count=1000000 of=\/root\/1Gb.file<\/p>\n\n\n\n

#dd if=\/root\/1Gb.file bs=64k | dd of=\/dev\/null<\/p>\n\n\n\n

\u901a\u8fc7\u4ee5\u4e0a\u4e24\u4e2a\u547d\u4ee4\u8f93\u51fa\u7684\u547d\u4ee4\u6267\u884c\u65f6\u95f4\uff0c\u53ef\u4ee5\u8ba1\u7b97\u51fa\u786c\u76d8\u7684\u8bfb\u3001\u5199\u901f\u5ea6\u3002<\/p>\n\n\n\n

13.<\/strong>\u786e\u5b9a\u786c\u76d8\u7684\u6700\u4f73\u5757\u5927\u5c0f\uff1a<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/zero bs=1024 count=1000000 of=\/root\/1Gb.file<\/p>\n\n\n\n

#dd if=\/dev\/zero bs=2048 count=500000 of=\/root\/1Gb.file<\/p>\n\n\n\n

#dd if=\/dev\/zero bs=4096 count=250000 of=\/root\/1Gb.file<\/p>\n\n\n\n

#dd if=\/dev\/zero bs=8192 count=125000 of=\/root\/1Gb.file<\/p>\n\n\n\n

\u901a\u8fc7\u6bd4\u8f83\u4ee5\u4e0a\u547d\u4ee4\u8f93\u51fa\u4e2d\u6240\u663e\u793a\u7684\u547d\u4ee4\u6267\u884c\u65f6\u95f4\uff0c\u5373\u53ef\u786e\u5b9a\u7cfb\u7edf\u6700\u4f73\u7684\u5757\u5927\u5c0f\u3002<\/p>\n\n\n\n

14.<\/strong>\u4fee\u590d\u786c\u76d8\uff1a<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/sda of=\/dev\/sda \u6216dd if=\/dev\/hda of=\/dev\/hda<\/p>\n\n\n\n

\u5f53\u786c\u76d8\u8f83\u957f\u65f6\u95f4(\u4e00\u5e74\u4ee5\u4e0a)\u653e\u7f6e\u4e0d\u4f7f\u7528\u540e\uff0c\u78c1\u76d8\u4e0a\u4f1a\u4ea7\u751fmagnetic flux \npoint\uff0c\u5f53\u78c1\u5934\u8bfb\u5230\u8fd9\u4e9b\u533a\u57df\u65f6\u4f1a\u9047\u5230\u56f0\u96be\uff0c\u5e76\u53ef\u80fd\u5bfc\u81f4I\/O\u9519\u8bef\u3002\u5f53\u8fd9\u79cd\u60c5\u51b5\u5f71\u54cd\u5230\u786c\u76d8\u7684\u7b2c\u4e00\u4e2a\u6247\u533a\u65f6\uff0c\u53ef\u80fd\u5bfc\u81f4\u786c\u76d8\u62a5\u5e9f\u3002\u4e0a\u8fb9\u7684\u547d\u4ee4\u6709\u53ef\u80fd\u4f7f\u8fd9\u4e9b\u6570\n \u636e\u8d77\u6b7b\u56de\u751f\u3002\u5e76\u4e14\u8fd9\u4e2a\u8fc7\u7a0b\u662f\u5b89\u5168\u3001\u9ad8\u6548\u7684\u3002<\/p>\n\n\n\n

15.<\/strong>\u5229\u7528<\/strong>netcat<\/strong>\u8fdc\u7a0b\u5907\u4efd<\/strong><\/p>\n\n\n\n

#dd if=\/dev\/hda bs=16065b | netcat < targethost-IP > 1234<\/p>\n\n\n\n

\u5728\u6e90\u4e3b\u673a\u4e0a\u6267\u884c\u6b64\u547d\u4ee4\u5907\u4efd\/dev\/hda<\/p>\n\n\n\n

#netcat -l -p 1234 | dd of=\/dev\/hdc bs=16065b<\/p>\n\n\n\n

\u5728\u76ee\u7684\u4e3b\u673a\u4e0a\u6267\u884c\u6b64\u547d\u4ee4\u6765\u63a5\u6536\u6570\u636e\u5e76\u5199\u5165\/dev\/hdc<\/p>\n\n\n\n

#netcat -l -p 1234 | bzip2 > partition.img<\/p>\n\n\n\n

#netcat -l -p 1234 | gzip > partition.img<\/p>\n\n\n\n

\u4ee5\u4e0a\u4e24\u6761\u6307\u4ee4\u662f\u76ee\u7684\u4e3b\u673a\u6307\u4ee4\u7684\u53d8\u5316\u5206\u522b\u91c7\u7528bzip2\u3001gzip\u5bf9\u6570\u636e\u8fdb\u884c\u538b\u7f29\uff0c\u5e76\u5c06\u5907\u4efd\u6587\u4ef6\u4fdd\u5b58\u5728\u5f53\u524d\u76ee\u5f55\u3002<\/p>\n\n\n\n

16.<\/strong>\u5c06\u4e00\u4e2a\u5927\u89c6\u9891\u6587\u4ef6\u7684\u7b2c<\/strong>i<\/strong>\u4e2a\u5b57\u8282\u7684\u503c\u6539\u6210<\/strong>0x41<\/strong>\uff08\u5927\u5199\u5b57\u6bcd<\/strong>A<\/strong>\u7684<\/strong>ASCII<\/strong>\u503c\uff09<\/strong><\/p>\n\n\n\n

#echo A | dd of=bigfile seek=$i bs=1 count=1 conv=notrunc<\/p>\n\n\n\n

17.<\/strong>\u5efa\u7acb<\/strong>linux<\/strong>\u865a\u62df\u76d8\uff0c\u7528\u6587\u4ef6\u6a21\u62df\u78c1\u76d8<\/strong><\/p>\n\n\n\n

\u5728\u8fdb\u884clinux\u7684\u5b9e\u9a8c\u4e2d\uff0c\u5982\u679c\u6ca1\u6709\u591a\u4f59\u7684\u786c\u76d8\u6765\u505a\u6d4b\u8bd5\u3002\u5219\u53ef\u4ee5\u5728linux\u4e0b\u4f7f\u7528\u6587\u4ef6\u6765\u6a21\u62df\u78c1\u76d8\uff0c\u4ee5\u4f9b\u6d4b\u8bd5\u76ee\u7684\u3002<\/p>\n\n\n\n

\u5176\u6a21\u62df\u8fc7\u7a0b\u5982\u4e0b\u6240\u793a\uff0c\u6458\u5f55\u81ea\u300aOracle\u6570\u636e\u5e93\u6838\u5fc3\u6280\u672f\u4e0e\u5b9e\u52a1\u8be6\u89e3\uff0d\u6559\u4f60\u5982\u4f55\u6210\u4e3aOracle 10g OCP\u300b\u4e00\u4e66\u3002<\/p>\n\n\n\n

1)\u4ee5root\u7528\u6237\u521b\u5efa\u4e00\u4e2aASM\u78c1\u76d8\u6240\u5728\u7684\u76ee\u5f55\u3002<\/p>\n\n\n\n

# mkdir \u2013p \/u01\/asmdisks<\/p>\n\n\n\n

2)\u901a\u8fc7dd\u547d\u4ee4\u521b\u5efa6\u4e2a400M\u5927\u5c0f\u7684\u6587\u4ef6\uff0c\u6bcf\u4e2a\u6587\u4ef6\u4ee3\u8868\u4e00\u5757\u78c1\u76d8\u3002<\/p>\n\n\n

[root@book u01]<\/p>\n\n\n\n

# cd asmdisks\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# dd if=\/dev\/zero of=asm_disk1 bs=1024k count=400\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# dd if=\/dev\/zero of=asm_disk2 bs=1024k count=400\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# dd if=\/dev\/zero of=asm_disk3 bs=1024k count=400\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# dd if=\/dev\/zero of=asm_disk4 bs=1024k count=400\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# dd if=\/dev\/zero of=asm_disk5 bs=1024k count=400\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# dd if=\/dev\/zero of=asm_disk6 bs=1024k count=400\n\n<\/p>\n\n\n\n

3)\u5c06\u8fd9\u4e9b\u6587\u4ef6\u4e0e\u88f8\u8bbe\u5907\u5173\u8054\u3002<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# chmod 777 asm_disk*\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# losetup \/dev\/loop1 asm_disk1\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# losetup \/dev\/loop2 asm_disk2\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# losetup \/dev\/loop3 asm_disk3\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# losetup \/dev\/loop4 asm_disk4\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# losetup \/dev\/loop5 asm_disk5\n<\/p>\n\n\n

[root@book asmdisks]<\/p>\n\n\n\n

# losetup \/dev\/loop6 asm_disk6\n\n<\/p>\n\n\n\n

\u6ce8\u610f\uff1a\u5982\u679c\u8981\u5220\u9664\u901a\u8fc7dd\u6a21\u62df\u51fa\u7684\u865a\u62df\u78c1\u76d8\u6587\u4ef6\u7684\u8bdd\uff0c\u76f4\u63a5\u5220\u9664\u6a21\u62df\u51fa\u7684\u78c1\u76d8\u6587\u4ef6<\/p>\n\n\n\n

\uff08\u4e5f\u5c31\u662fasm_disk1\u3001asm_disk2\u2026asm_disk6\uff09\u8fd8\u4e0d\u591f\uff0c\u8fd8\u5fc5\u987b\u6267\u884closetup -d \/dev\/loopN\uff0c\u5728\u8fd9\u91ccN\u4ece1\u52306\u3002\u5426\u5219\uff0c\u78c1\u76d8\u6587\u4ef6\u6240\u5360\u7528\u7684\u78c1\u76d8\u7a7a\u95f4\u4e0d\u80fd\u91ca\u653e<\/p>\n\n\n\n

\u4e09\u3001\/dev\/null\u548c\/dev\/zero\u7684\u533a\u522b<\/h1>\n\n\n\n

\/dev\/null\uff0c\u5916\u53f7\u53eb\u65e0\u5e95\u6d1e\uff0c\u4f60\u53ef\u4ee5\u5411\u5b83\u8f93\u51fa\u4efb\u4f55\u6570\u636e\uff0c\u5b83\u901a\u5403\uff0c\u5e76\u4e14\u4e0d\u4f1a\u6491\u7740\uff01<\/p>\n\n\n\n

\/dev\/zero\uff0c\u662f\u4e00\u4e2a\u8f93\u5165\u8bbe\u5907\uff0c\u4f60\u53ef\u4f60\u7528\u5b83\u6765\u521d\u59cb\u5316\u6587\u4ef6\u3002\u8be5\u8bbe\u5907\u65e0\u7a77\u5c3d\u5730\u63d0\u4f9b0\uff0c\u53ef\u4ee5\u4f7f\u7528\u4efb\u4f55\u4f60\u9700\u8981\u7684\u6570\u76ee\u2014\u2014\u8bbe\u5907\u63d0\u4f9b\u7684\u8981\u591a\u7684\u591a\u3002\u4ed6\u53ef\u4ee5\u7528\u4e8e\u5411\u8bbe\u5907\u6216\u6587\u4ef6\u5199\u5165\u5b57\u7b26\u4e320\u3002<\/p>\n\n\n\n

\/dev\/null------\u5b83\u662f\u7a7a\u8bbe\u5907\uff0c\u4e5f\u79f0\u4e3a\u4f4d\u6876\uff08bit bucket\uff09\u3002\u4efb\u4f55\u5199\u5165\u5b83\u7684\u8f93\u51fa\u90fd\u4f1a\u88ab\u629b\u5f03\u3002\u5982\u679c\u4e0d\u60f3\u8ba9\u6d88\u606f\u4ee5\u6807\u51c6\u8f93\u51fa\u663e\u793a\u6216\u5199\u5165\u6587\u4ef6\uff0c\u90a3\u4e48\u53ef\u4ee5\u5c06\u6d88\u606f\u91cd\u5b9a\u5411\u5230\u4f4d\u6876\u3002<\/p>\n\n\n\n

#if=\/dev\/zero of=.\/test.txt bs=1k count=1
\n#ls \u2013l<\/p>\n\n\n\n

total 4
\n-rw-r--r--    1 oracle   dba    \n     1024 Jul 15 16:56 test.txt<\/p>\n\n\n\n

#find \/ -name\naccess_log  2>\/dev\/null<\/p>\n\n\n\n

3.1\u4f7f\u7528\/dev\/null <\/h2>\n\n\n\n

\u628a\/dev\/null\u770b\u4f5c\"\u9ed1\u6d1e\"\uff0c \u5b83\u7b49\u4ef7\u4e8e\u4e00\u4e2a\u53ea\u5199\u6587\u4ef6\uff0c\u6240\u6709\u5199\u5165\u5b83\u7684\u5185\u5bb9\u90fd\u4f1a\u6c38\u8fdc\u4e22\u5931.\uff0c\u800c\u5c1d\u8bd5\u4ece\u5b83\u90a3\u513f\u8bfb\u53d6\u5185\u5bb9\u5219\u4ec0\u4e48\u4e5f\u8bfb\u4e0d\u5230\u3002\u7136\u800c\uff0c \/dev\/null\u5bf9\u547d\u4ee4\u884c\u548c\u811a\u672c\u90fd\u975e\u5e38\u7684\u6709\u7528<\/p>\n\n\n\n

\u7981\u6b62\u6807\u51c6\u8f93\u51fa<\/strong><\/p>\n\n\n\n

#cat $filename\n>\/dev\/null<\/p>\n\n\n\n

\u6587\u4ef6\u5185\u5bb9\u4e22\u5931\uff0c\u800c\u4e0d\u4f1a\u8f93\u51fa\u5230\u6807\u51c6\u8f93\u51fa.<\/p>\n\n\n\n

\u7981\u6b62\u6807\u51c6\u9519\u8bef<\/strong><\/p>\n\n\n\n

#rm $badname\n2>\/dev\/null<\/p>\n\n\n\n

\u8fd9\u6837\u9519\u8bef\u4fe1\u606f[\u6807\u51c6\u9519\u8bef]\u5c31\u88ab\u4e22\u5230\u592a\u5e73\u6d0b\u53bb\u4e86<\/p>\n\n\n\n

\u7981\u6b62\u6807\u51c6\u8f93\u51fa\u548c\u6807\u51c6\u9519\u8bef\u7684\u8f93\u51fa<\/strong><\/p>\n\n\n\n

#cat $filename\n2>\/dev\/null >\/dev\/null<\/p>\n\n\n\n

\u5982\u679c\"f<\/em>i<\/em>l<\/em>e<\/em>n<\/em>a<\/em>m<\/em>e<\/em>\"\u4e0d\u5b58\u5728\uff0c\u5c06\u4e0d\u4f1a\u6709\u4efb\u4f55\u9519\u8bef\u4fe1\u606f\u63d0\u793a\uff1b\u5982\u679c\"<\/p>\n\n\n\n

filename\"\u5b58\u5728\uff0c \u6587\u4ef6\u7684\u5185\u5bb9\u4e0d\u4f1a\u6253\u5370\u5230\u6807\u51c6\u8f93\u51fa\u3002<\/p>\n\n\n\n

\u56e0\u6b64\uff0c\u4e0a\u9762\u7684\u4ee3\u7801\u6839\u672c\u4e0d\u4f1a\u8f93\u51fa\u4efb\u4f55\u4fe1\u606f\u3002\u5f53\u53ea\u60f3\u6d4b\u8bd5\u547d\u4ee4\u7684\u9000\u51fa\u7801\u800c\u4e0d\u60f3\u6709\u4efb\u4f55\u8f93\u51fa\u65f6\u975e\u5e38\u6709\u7528\u3002<\/p>\n\n\n\n

#cat $filename\n&>\/dev\/null<\/p>\n\n\n\n

\u8fd9\u6837\u5176\u5b9e\u4e5f\u53ef\u4ee5\uff0c \u7531 Baris Cicek \u6307\u51fa<\/p>\n\n\n\n

\u81ea\u52a8\u6e05\u7a7a\u65e5\u5fd7\u6587\u4ef6\u7684\u5185\u5bb9<\/strong><\/p>\n\n\n\n

Deleting contents of a file, but preserving the file itself, with all\nattendant permissions (from Example 2-1 and Example 2-3): <\/p>\n\n\n\n

#cat \/dev\/null\n> \/var\/log\/messages
\n#  : > \/var\/log\/messages   \u6709\u540c\u6837\u7684\u6548\u679c\uff0c \u4f46\u4e0d\u4f1a\u4ea7\u751f\u65b0\u7684\u8fdb\u7a0b.\uff08\u56e0\u4e3a:\u662f\u5185\u5efa\u7684\uff09
\n#cat \/dev\/null > \/var\/log\/wtmp<\/p>\n\n\n\n

\u7279\u522b\u9002\u5408\u5904\u7406\u8fd9\u4e9b\u7531\u5546\u4e1aWeb\u7ad9\u70b9\u53d1\u9001\u7684\u8ba8\u538c\u7684\"cookies\"<\/p>\n\n\n\n

\u9690\u85cf<\/strong>cookie<\/strong>\u800c\u4e0d\u518d\u4f7f\u7528<\/strong><\/p>\n\n\n\n

#if [ -f\n~\/.netscape\/cookies ]  # \u5982\u679c\u5b58\u5728\u5219\u5220\u9664.
\n#then
\n#rm -f ~\/.netscape\/cookies
\n#fi
\n#ln -s \/dev\/null ~\/.netscape\/cookies<\/p>\n\n\n\n

\u73b0\u5728\u6240\u6709\u7684cookies\u90fd\u4f1a\u4e22\u5165\u9ed1\u6d1e\u800c\u4e0d\u4f1a\u4fdd\u5b58\u5728\u78c1\u76d8\u4e0a\u4e86.<\/p>\n\n\n\n

3.2\u4f7f\u7528\/dev\/zero<\/h2>\n\n\n\n

\u50cf\/dev\/null\u4e00\u6837\uff0c \/dev\/zero\u4e5f\u662f\u4e00\u4e2a\u4f2a\u6587\u4ef6\uff0c \n\u4f46\u5b83\u5b9e\u9645\u4e0a\u4ea7\u751f\u8fde\u7eed\u4e0d\u65ad\u7684null\u7684\u6d41\uff08\u4e8c\u8fdb\u5236\u7684\u96f6\u6d41\uff0c\u800c\u4e0d\u662fASCII\u578b\u7684\uff09\u3002 \u5199\u5165\u5b83\u7684\u8f93\u51fa\u4f1a\u4e22\u5931\u4e0d\u89c1\uff0c \n\u800c\u4ece\/dev\/zero\u8bfb\u51fa\u4e00\u8fde\u4e32\u7684null\u4e5f\u6bd4\u8f83\u56f0\u96be\uff0c \u867d\u7136\u8fd9\u4e5f\u80fd\u901a\u8fc7od\u6216\u4e00\u4e2a\u5341\u516d\u8fdb\u5236\u7f16\u8f91\u5668\u6765\u505a\u5230\u3002 \n\/dev\/zero\u4e3b\u8981\u7684\u7528\u5904\u662f\u7528\u6765\u521b\u5efa\u4e00\u4e2a\u6307\u5b9a\u957f\u5ea6\u7528\u4e8e\u521d\u59cb\u5316\u7684\u7a7a\u6587\u4ef6\uff0c\u5c31\u50cf\u4e34\u65f6\u4ea4\u6362\u6587\u4ef6<\/p>\n\n\n\n

\u7528<\/strong>\/dev\/zero<\/strong>\u521b\u5efa\u4e00\u4e2a\u4ea4\u6362\u4e34\u65f6\u6587\u4ef6<\/strong><\/p>\n\n\n\n

#!\/bin\/bash <\/p>\n\n\n\n

  # \u521b\u5efa\u4e00\u4e2a\u4ea4\u6362\u6587\u4ef6. <\/p>\n\n\n\n

 \nROOT_UID=0 # Root \u7528\u6237\u7684 $UID \u662f 0. <\/p>\n\n\n\n

 \nE_WRONG_USER=65 # \u4e0d\u662f root? <\/p>\n\n\n\n

 \nFILE=\/swap <\/p>\n\n\n\n

 \nBLOCKSIZE=1024<\/p>\n\n\n\n

 \nMINBLOCKS=40 <\/p>\n\n\n\n

 \nSUCCESS=0<\/p>\n\n\n\n

  # \u8fd9\u4e2a\u811a\u672c\u5fc5\u987b\u7528root\u6765\u8fd0\u884c.<\/p>\n\n\n\n

  if\n[ \"U<\/em>I<\/em>D<\/em>\"\u2212n<\/em>e<\/em>\"<\/p>\n\n\n\n

ROOT_UID\" ] <\/p>\n\n\n\n

  \nthen<\/p>\n\n\n\n

  \necho; echo \"You must be root to run this script.\"; echo <\/p>\n\n\n\n

  \nexit $E_WRONG_USER<\/p>\n\n\n\n

  fi <\/p>\n\n\n\n

 \nblocks={1:-<\/p>\n\n\n\n

MINBLOCKS} # \u5982\u679c\u547d\u4ee4\u884c\u6ca1\u6709\u6307\u5b9a\uff0c<\/p>\n\n\n\n

  #+ \u5219\u8bbe\u7f6e\u4e3a\u9ed8\u8ba4\u768440\u5757. <\/p>\n\n\n\n

  # \u4e0a\u9762\u8fd9\u53e5\u7b49\u540c\u5982\uff1a<\/p>\n\n\n\n

  #\n-------------------------------------------------- <\/p>\n\n\n\n

  #\nif [ -n \"$1\" ] <\/p>\n\n\n\n

  #\nthen <\/p>\n\n\n\n

  #\nblocks=$1 <\/p>\n\n\n\n

  #\nelse <\/p>\n\n\n\n

  #\nblocks=$MINBLOCKS <\/p>\n\n\n\n

  #\nfi <\/p>\n\n\n\n

  #\n--------------------------------------------------<\/p>\n\n\n\n

 if [\n\"b<\/em>l<\/em>o<\/em>c<\/em>k<\/em>s<\/em>\"\u2212l<\/em>t<\/em><\/p>\n\n\n\n

MINBLOCKS ] <\/p>\n\n\n\n

 then<\/p>\n\n\n\n

 blocks=$MINBLOCKS # \u6700\u5c11\u8981\u6709 40 \u4e2a\u5757\u957f. <\/p>\n\n\n\n

 fi <\/p>\n\n\n\n

 echo\n\"Creating swap file of size $blocks blocks (KB).\" <\/p>\n\n\n\n

 dd\nif=\/dev\/zero of=F<\/em>I<\/em>L<\/em>E<\/em>b<\/em>s<\/em>=<\/p>\n\n\n\n

BLOCKSIZE count=$blocks # \u628a\u96f6\u5199\u5165\u6587\u4ef6. <\/p>\n\n\n\n

 mkswap F<\/em>I<\/em>L<\/em>E<\/em><\/p>\n\n\n\n

blocks # \u5c06\u6b64\u6587\u4ef6\u5efa\u4e3a\u4ea4\u6362\u6587\u4ef6\uff08\u6216\u79f0\u4ea4\u6362\u5206\u533a\uff09. <\/p>\n\n\n\n

 swapon $FILE # \u6fc0\u6d3b\u4ea4\u6362\u6587\u4ef6. <\/p>\n\n\n\n

 echo\n\"Swap file created and activated.\" <\/p>\n\n\n\n

 exit $SUCCESS <\/p>\n\n\n\n

\u5173\u4e8e \/dev\/zero \u7684\u53e6\u4e00\u4e2a\u5e94\u7528\u662f\u4e3a\u7279\u5b9a\u7684\u76ee\u7684\u800c\u7528\u96f6\u53bb\u586b\u5145\u4e00\u4e2a\u6307\u5b9a\u5927\u5c0f\u7684\u6587\u4ef6\uff0c \u5982\u6302\u8f7d\u4e00\u4e2a\u6587\u4ef6\u7cfb\u7edf\u5230\u73af\u56de\u8bbe\u5907 \uff08loopback device\uff09\u6216\"\u5b89\u5168\u5730\" \u5220\u9664\u4e00\u4e2a\u6587\u4ef6<\/p>\n\n\n\n

\u4f8b\u5b50<\/strong>\u521b\u5efa<\/strong>ramdisk<\/strong><\/p>\n\n\n\n

#!\/bin\/bash <\/p>\n\n\n\n

 #\nramdisk.sh <\/p>\n\n\n\n

 #\n\"ramdisk\"\u662f\u7cfb\u7edfRAM\u5185\u5b58\u7684\u4e00\u6bb5\uff0c <\/p>\n\n\n\n

 #+ \u5b83\u53ef\u4ee5\u88ab\u5f53\u6210\u662f\u4e00\u4e2a\u6587\u4ef6\u7cfb\u7edf\u6765\u64cd\u4f5c. <\/p>\n\n\n\n

 # \u5b83\u7684\u4f18\u70b9\u662f\u5b58\u53d6\u901f\u5ea6\u975e\u5e38\u5feb (\u5305\u62ec\u8bfb\u548c\u5199). <\/p>\n\n\n\n

 # \u7f3a\u70b9: \u6613\u5931\u6027, \u5f53\u8ba1\u7b97\u673a\u91cd\u542f\u6216\u5173\u673a\u65f6\u4f1a\u4e22\u5931\u6570\u636e.<\/p>\n\n\n\n

 #+ \u4f1a\u51cf\u5c11\u7cfb\u7edf\u53ef\u7528\u7684RAM. <\/p>\n\n\n\n

 # 10\n# \u90a3\u4e48ramdisk\u6709\u4ec0\u4e48\u4f5c\u7528\u5462?<\/p>\n\n\n\n

 # \u4fdd\u5b58\u4e00\u4e2a\u8f83\u5927\u7684\u6570\u636e\u96c6\u5728ramdisk, \u6bd4\u5982\u4e00\u5f20\u8868\u6216\u5b57\u5178, <\/p>\n\n\n\n

 #+ \u8fd9\u6837\u53ef\u4ee5\u52a0\u901f\u6570\u636e\u67e5\u8be2, \u56e0\u4e3a\u5728\u5185\u5b58\u91cc\u67e5\u627e\u6bd4\u5728\u78c1\u76d8\u91cc\u67e5\u627e\u5feb\u5f97\u591a.<\/p>\n\n\n\n

 \nE_NON_ROOT_USER=70 # \u5fc5\u987b\u7528root\u6765\u8fd0\u884c. <\/p>\n\n\n\n

 \nROOTUSER_NAME=root<\/p>\n\n\n\n

 \nMOUNTPT=\/mnt\/ramdisk <\/p>\n\n\n\n

 \nSIZE=2000 # 2K \u4e2a\u5757\n(\u53ef\u4ee5\u5408\u9002\u7684\u505a\u4fee\u6539)<\/p>\n\n\n\n

 \nBLOCKSIZE=1024 # \u6bcf\u5757\u67091K (1024 byte) \u7684\u5927\u5c0f <\/p>\n\n\n\n

 \nDEVICE=\/dev\/ram0 # \u7b2c\u4e00\u4e2a ram \u8bbe\u5907 <\/p>\n\n\n\n

 \nusername=`id -nu` <\/p>\n\n\n\n

  if\n[ \"u<\/em>s<\/em>e<\/em>r<\/em>n<\/em>a<\/em>m<\/em>e<\/em>\"!=\"<\/p>\n\n\n\n

ROOTUSER_NAME\" ] <\/p>\n\n\n\n

 \nthen <\/p>\n\n\n\n

   \necho \"Must be root to run \\\"`basename $0`\\\".\"<\/p>\n\n\n\n

   \nexit $E_NON_ROOT_USER <\/p>\n\n\n\n

  fi <\/p>\n\n\n\n

   if\n[ ! -d \"$MOUNTPT\" ] # \u6d4b\u8bd5\u6302\u8f7d\u70b9\u662f\u5426\u5df2\u7ecf\u5b58\u5728\u4e86,<\/p>\n\n\n\n

 \nthen #+ \u5982\u679c\u8fd9\u4e2a\u811a\u672c\u5df2\u7ecf\u8fd0\u884c\u4e86\u597d\u51e0\u6b21\u4e86\u5c31\u4e0d\u4f1a\u518d\u5efa\u8fd9\u4e2a\u76ee\u5f55\u4e86<\/p>\n\n\n\n

   \nmkdir $MOUNTPT #+ \u56e0\u4e3a\u524d\u9762\u5df2\u7ecf\u5efa\u7acb\u4e86. <\/p>\n\n\n\n

  fi <\/p>\n\n\n\n

  dd\nif=\/dev\/zero of=D<\/em>E<\/em>V<\/em>I<\/em>C<\/em>E<\/em>c<\/em>o<\/em>u<\/em>n<\/em>t<\/em>=<\/p>\n\n\n\n

SIZE bs=$BLOCKSIZE<\/p>\n\n\n\n

   # \u628aRAM\u8bbe\u5907\u7684\u5185\u5bb9\u7528\u96f6\u586b\u5145.                                               <\/p>\n\n\n\n

   # \u4e3a\u4f55\u9700\u8981\u8fd9\u4e48\u505a? <\/p>\n\n\n\n

 \nmke2fs $DEVICE # \u5728RAM\u8bbe\u5907\u4e0a\u521b\u5efa\u4e00\u4e2aext2\u6587\u4ef6\u7cfb\u7edf. <\/p>\n\n\n\n

 \nmount D<\/em>E<\/em>V<\/em>I<\/em>C<\/em>E<\/em><\/p>\n\n\n\n

MOUNTPT # \u6302\u8f7d\u8bbe\u5907. <\/p>\n\n\n\n

 \nchmod 777 $MOUNTPT # \u4f7f\u666e\u901a\u7528\u6237\u4e5f\u53ef\u4ee5\u5b58\u53d6\u8fd9\u4e2aramdisk. <\/p>\n\n\n\n

  # \u4f46\u662f, \u53ea\u80fd\u7531root\u6765\u7f37\u8f7d\u5b83. <\/p>\n\n\n\n

 \necho \"\\\"$MOUNTPT\\\" now available for use.\" <\/p>\n\n\n\n

 # \u73b0\u5728 ramdisk \u5373\u4f7f\u666e\u901a\u7528\u6237\u4e5f\u53ef\u4ee5\u7528\u6765\u5b58\u53d6\u6587\u4ef6\u4e86. <\/p>\n\n\n\n

 # \u6ce8\u610f, ramdisk\u662f\u6613\u5931\u7684, \u6240\u4ee5\u5f53\u8ba1\u7b97\u673a\u7cfb\u7edf\u91cd\u542f\u6216\u5173\u673a\u65f6ramdisk\u91cc\u7684\u5185\u5bb9\u4f1a\u6d88\u5931.<\/p>\n\n\n\n

 # \u62f7\u8d1d\u6240\u6709\u4f60\u60f3\u4fdd\u5b58\u6587\u4ef6\u5230\u4e00\u4e2a\u5e38\u89c4\u7684\u78c1\u76d8\u76ee\u5f55\u4e0b. <\/p>\n\n\n\n

 # \u91cd\u542f\u4e4b\u540e, \u8fd0\u884c\u8fd9\u4e2a\u811a\u672c\u518d\u6b21\u5efa\u7acb\u8d77\u4e00\u4e2a ramdisk. <\/p>\n\n\n\n

 # \u4ec5\u91cd\u65b0\u52a0\u8f7d \/mnt\/ramdisk \u800c\u6ca1\u6709\u5176\u4ed6\u7684\u6b65\u9aa4\u5c06\u4e0d\u4f1a\u6b63\u786e\u5de5\u4f5c. <\/p>\n\n\n\n

 # \u5982\u679c\u52a0\u4ee5\u6539\u8fdb, \u8fd9\u4e2a\u811a\u672c\u53ef\u4ee5\u653e\u5728 \/etc\/rc.d\/rc.local,<\/p>\n\n\n\n

 #+ \u4ee5\u4f7f\u7cfb\u7edf\u542f\u52a8\u65f6\u80fd\u81ea\u52a8\u8bbe\u7acb\u4e00\u4e2aramdisk. <\/p>\n\n\n\n

 # \u8fd9\u6837\u5f88\u5408\u9002\u901f\u5ea6\u8981\u6c42\u9ad8\u7684\u6570\u636e\u5e93\u670d\u52a1\u5668. <\/p>\n\n\n\n

\u00a0exit 0<\/p>\n\n\n\n

<\/p>\n\n\n\n

Links:

https:\/\/www.cnblogs.com\/jikexianfeng\/p\/6103500.html

<\/p>\n","protected":false},"excerpt":{"rendered":"

\u4e00\u3001dd\u547d\u4ee4\u7684\u89e3\u91ca dd\uff1a\u7528\u6307\u5b9a\u5927\u5c0f\u7684\u5757\u62f7\u8d1d\u4e00\u4e2a\u6587\u4ef6\uff0c\u5e76\u5728\u62f7\u8d1d\u7684\u540c\u65f6\u8fdb\u884c\u6307\u5b9a\u7684\u8f6c … \u7ee7\u7eed\u9605\u8bfb →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[287],"tags":[],"class_list":["post-1683","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts\/1683","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/comments?post=1683"}],"version-history":[{"count":0,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/posts\/1683\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/media?parent=1683"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/categories?post=1683"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.xiaobo.li\/notes\/wp-json\/wp\/v2\/tags?post=1683"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}