Linux Fundamentals 17

1.raid  (redandent array of independent disks)      software rai md   can combine any block device     mdadm [mode <raiddevice> [option] < component_device>        mdadm  Modelling Tools          -A  assembly mode         -C  Create mode          -F  Monitoring Mode         -D  Show array details          management mode              -f  Equipment Damage             -r   Device removal             -a  replacement equipment                        -C  Create mode &NBSP;&NBSP;&NBSP;&Nbsp;           -n#  number of devices used to create RAID               -x#  number of hot spares               -l  Specify the RAID level               -a=--auto yes   create files automatically for the RAID device created                  eg:mdadm -c /dev/md0 -a  yes -l 0 -n 2 /dev/sdb{1.2}       2.while   Condition Testing  ; do     cyclic body done3.until  test conditions  ; do      Cyclic body done4.bash  programming combination test conditions      logic and  : multiple conditions simultaneously satisfy     [  condition ] && [ condition2]    [ condition -a  Condition2 ]    [[ condition && condition2 ]]          The first two use single or double brackets, but && is not allowed in parentheses, so the third can use double brackets          logic or      [ condition ] | |  [ condition2 ]    [ condition ] -o [ condition2  ]    [[ condition | |  condition2 ]]     the third type can only use double brackets         ! (condition 1  or   condition 2) = ! condition 1  and  ! condition 2    ! (Condition 1  and   condition 2)  = ! condition 1  or  ! condition 2

Linux Fundamentals 17