dd命令

湖北佛

sys@OMREP> shutdown immediate;


[oracle@localhost omrep]$ pwd
/u01/app/oracle/oradata/omrep

[oracle@localhost omrep]$ dd if=users01.dbf of=users01.bak
360976+0 records in
360976+0 records out
184819712 bytes (185 MB) copied, 1.49942 s, 123 MB/s

[oracle@localhost omrep]$ dd if=users01.bak of=users01.dbf bs=8192 count=1 conv=notrunc skip=151 seek=151                              
1+0 records in
1+0 records out
8192 bytes (8.2 kB) copied, 8.0675e-05 s, 102 MB/s
[oracle@localhost omrep]$ ll users*
-rw-r-----  1 oracle oinstall 184819712 Sep  4 15:02 users01.bak
-rw-r-----. 1 oracle oinstall 184819712 Sep  4 15:07 users01.dbf

[oracle@localhost omrep]$ dd if=users01.bak of=users01.dbf bs=8192 count=1 skip=151 seek=151            
1+0 records in
1+0 records out
8192 bytes (8.2 kB) copied, 0.000102634 s, 79.8 MB/s
[oracle@localhost omrep]$ ll users*
-rw-r-----  1 oracle oinstall 184819712 Sep  4 15:02 users01.bak
-rw-r-----. 1 oracle oinstall   1245184 Sep  4 15:07 users01.dbf

sys@OMREP> select 1245184/(151+1) from dual;

1245184/(151+1)
---------------
           8192