Linux 基礎知識（六.二）

1、復制/etc/rc.d/rc.sysinit至/tmp目錄，將/tmp/rc.sysinit文件中的以至少一個空白字符開頭的行的行首加#

[root@server01 tmp]# cp /etc/rc.d/rc.sysinit /tmp/

[root@server01 tmp]# sed -n "s@^[[:space:]]\+@#&@gp" rc.sysinit

• #    . /etc/sysconfig/network

• #    HOSTNAME=localhost

• # mount -n -t proc /proc /proc

• # mount -n -t sysfs /sys /sys >/dev/null 2>&1

• # modprobe usbcore >/dev/null 2>&1 && mount -n -t usbfs /proc/bus/usb /proc/bus/usb

• # mount -n -t usbfs /proc/bus/usb /proc/bus/usb

• # if [ -r "/selinux/enforce" ] ; then

• # SELINUX_STATE=$(cat "/selinux/enforce")

• # else

• # # assume enforcing if you can't read it

• # SELINUX_STATE=1

• # fi

• ……
  

• #  chmod 0664 /var/run/utmpx /var/log/wtmpx

• #       /tmp/kde-* /tmp/ksocket-* /tmp/mc-* /tmp/mcop-* /tmp/orbit-*  \

• #       /tmp/scrollkeeper-*  /tmp/ssh-* \

• #       /dev/.in_sysinit

• # curswap=$(awk '/^\/dev/ { print $1 }' /proc/swaps | while read x; do get_numeric_dev dec $x ; echo -n " "; done)

• # swappartitions=$(blkid -t TYPE=swap -o device)

• # if [ x"$swappartitions" != x ]; then

• # for partition in $swappartitions ; do

• # [ ! -e $partition ] && continue

• # majmin=$(get_numeric_dev dec $partition)

• # echo $curswap | grep -qw "$majmin" || action $"Enabling local swap partitions: " swapon $partition

• # done

• # fi

• #  if strstr "$cmdline" netprofile= ; then

• #    for arg in $cmdline ; do

• #        if [ "${arg##netprofile=}" != "${arg}" ]; then

• #    /usr/sbin/system-config-network-cmd –profile ${arg##netprofile=}

• #        fi

• #    done

• #  fi

• # touch /var/run/confirm

• #    /bin/plymouth –sysinit

2、復制/boot/grub/grub.conf至/tmp目錄，刪除/tmp/grub.conf文件中的行首的空白字符

[root@server01 tmp]# cp /boot/grub/grub.conf /tmp/

[root@server01 tmp]# sed -n "s@^[[:space:]]\+@@p" grub.conf

• root (hd0,0)

• kernel /vmlinuz-2.6.32-573.el6.x86_64 ro root=/dev/mapper/vg_server01-lv_root rd_NO_LUKS rd_LVM_LV=vg_server01/lv_root.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_NO_DM  KEYBOARDTYPE=pc KEYTABLE=us rd_LVM_LV=vg_server01/lv_swap rhgb quiet

• initrd /initramfs-2.6.32-573.el6.x86_64.img

3、刪除/tmp/rc.sysinit文件中以#開頭，且后面跟了至少一個空白字符的行的#和空白字符

[root@server01 tmp]# sed -rn "s@^#[[:space:]]+@@p" rc.sysinit 

• /etc/rc.d/rc.sysinit – run once at boot time

• Taken in part from Miquel van Smoorenburg's bcheckrc.

• Check SELinux status

• Print a text banner.

• Only read this once.

• Initialize hardware

• Set default affinity

• Load other user-defined modules

• Load modules (for backward compatibility with VARs)

• Configure kernel parameters

• Set the hostname.

• Sync waiting for storage.

• Device mapper & related initialization

• Start any MD RAID arrays that haven't been started yet

• Remount the root filesystem read-write.

• Clean up SELinux labels

• If relabeling, relabel mount points.

• Mount all other filesystems (except for NFS and /proc, which is already

• mounted). Contrary to standard usage,

• filesystems are NOT unmounted in single user mode.

• The 'no' applies to all listed filesystem types. See mount(8).

• Update quotas if necessary

• Check to see if a full relabel is needed

• Initialize pseudo-random number generator

• Configure machine if necessary.

• Clean out /.

• Do we need (w|u)tmpx files? We don't set them up, but the sysadmin might…

• Clean up /var.

• Clean up utmp/wtmp

• Clean up various /tmp bits

• Make ICE directory

• Start up swapping.

• Set up binfmt_misc

• Boot time profiles. Yes, this should be somewhere else.

• Now that we have all of our basic modules loaded and the kernel going,

• let's dump the syslog ring somewhere so we can find it later

• create the crash indicator flag to warn on crashes, offer fsck with timeout

• Let rhgb know that we're leaving rc.sysinit

4、為/tmp/grub.conf文件中的前三行的行首加#號

[root@server01 tmp]# sed -n "1,3s@^@#@p" grub.conf

• ## grub.conf generated by anaconda

• ##

• ## Note that you do not have to rerun grub after making changes to this file

5、將/etc/yum.repos.d/CentOS-Media.repo文件中所有的enabled=0或gpgcheck=0修改最后的0為1

[root@server01 tmp]# sed -rn "s@(enabled|gpgcheck)=0@\1=1@p" /etc/yum.repos.d/CentOS-Media.repo 

• enabled=1

6、每4小時執行一次對/etc目錄的備份，備份至/backuup目錄中，保存的目錄名稱為形如etc-201504020202

[root@server01 tmp]# crontab -e

* */4 * * * /bin/tar cvf /backup/etc-$(date +%Y%m%d%H%M%S) /etc/*

7、每周2，4，6備份/var/log/messages文件至/backup/message_logs目錄中，保存的文件名形如messages-20160402

[root@server01 tmp]# crontab -e

* * * * 2,4,6 /bin/cp /var/log/messages /backup/message_logs/messages-$(date +%Y%m%d)

8、每天每兩小時取當前系統/proc/meminfo文件中的所有以S開頭的信息至/stats/memory.txt文件中

[root@server01 message_logs]# mkdir /stats

[root@server01 ~]# crontab -e

* */2 * * * /bin/cat /proc/meminfo | /bin/grep -E "^[S]" &> /stats/memory.txt

9、工作日的工作時間內，每兩小時執行一次echo "howdy"

[root@server01 ~]# crontab -e

* 9-18/2 * * 1,2,3,4,5 /bin/echo "howdy"