Linux文件系统 1.0 一些基础操作

> 一些基础操作

# mke2fs  可以用来格式化ext2/3/4 并详细设置各项参数
```
[root@localhost ~]# mkfs -t ext4 /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
28112 inodes, 112420 blocks
5621 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
14 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
        8193, 24577, 40961, 57345, 73729
Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 28 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]# mount /dev/sdb1 /mnt
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                      8.4G 808M 7.2G 10% /
tmpfs 250M 0 250M 0% /dev/shm
/dev/sda1 485M 30M 430M 7% /boot
/dev/sdb1 107M 5.6M 96M 6% /mnt
[root@localhost ~]#
```

# 分区
fdisk -l
查看当前系统总分区信息

当你要分区的磁盘正在使用的时候，可能变动不能被内核知道
要注意如下报错：
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
```
[root@localhost ~]# fdisk /dev/sdb
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').
Command (m for help): m    <-- 帮助
Command action
   a toggle a bootable flag
   b edit bsd disklabel
   c toggle the dos compatibility flag
   d delete a partition           <--  删除分区
   l list known partition types
   m print this menu
   n add a new partition          <--  加新分区
   o create a new empty DOS partition table
   p print the partition table      <--    显示当前分割表
   q quit without saving changes     <--  退出，不保存
   s create a new empty Sun disklabel
   t change a partition's system id    <-- 修改分区的system id，用来说明这个分区类型
   u change display/entry units
   v verify the partition table
   w write table to disk and exit         <--  退出，保存
   x extra functionality (experts only)
Command (m for help): p              <--  显示当前分区
Disk /dev/sdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbce88505
   Device Boot Start End Blocks Id System
Command (m for help): n
Command action
   e extended
   p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-261, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-261, default 261): +100M       <--  100M 的分区
Command (m for help): p
Disk /dev/sdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbce88505
   Device Boot Start End Blocks Id System
/dev/sdb1 1 14 112423+ 83 Linux
Command (m for help): n
Command action
   e extended
   p primary partition (1-4)
e
Partition number (1-4): 2
First cylinder (15-261, default 15):
Using default value 15
Last cylinder, +cylinders or +size{K,M,G} (15-261, default 261):
Using default value 261
Command (m for help): p
Disk /dev/sdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbce88505
   Device Boot Start End Blocks Id System
/dev/sdb1 1 14 112423+ 83 Linux
/dev/sdb2 15 261 1984027+ 5 Extended
Command (m for help): n
Command action
   l logical (5 or over)
   p primary partition (1-4)
l
First cylinder (15-261, default 15):
Using default value 15
Last cylinder, +cylinders or +size{K,M,G} (15-261, default 261): +100M
Command (m for help): p
Disk /dev/sdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbce88505
   Device Boot Start End Blocks Id System
/dev/sdb1 1 14 112423+ 83 Linux
/dev/sdb2 15 261 1984027+ 5 Extended
/dev/sdb5 15 28 112423+ 83 Linux
Command (m for help): d
Partition number (1-5): 5
Command (m for help): p
Disk /dev/sdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbce88505
   Device Boot Start End Blocks Id System
/dev/sdb1 1 14 112423+ 83 Linux
/dev/sdb2 15 261 1984027+ 5 Extended
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]#
```
## 内核重载分区
partprobe  让内核读入新的分区表。

查看 内核中当前的分区： 
cat /proc/partitions

在RHEL 5.5中系统硬盘在分完区后可以直接使用partprobe更新分区，使内核识别分区。
在RHEL6中分区完毕后使用partprobe无法更新分区，必须重新启动服务器后，分区才可以被正常挂载。
partx -a /dev/sda  可以用于RHEL6

# 查看分区信息
```
查看uuid， 文件系统类型
[root@fs1 ~]# blkid /dev/sda1
/dev/sda1: UUID="7594f582-ab58-4c3b-ad68-a48e234a25aa" TYPE="ext4"

ext2/ext3/ext4
dumpe2fs:
[root@fs1 ~]# dumpe2fs /dev/sdb
```
# 修改分区label 名称
```
[root@www ~]# e2label 裝置名稱  新的Label名稱

例子：
[root@localhost mnt]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                      8.4G  808M  7.2G  10% /
tmpfs                 250M     0  250M   0% /dev/shm
/dev/sda1             485M   30M  430M   7% /boot
/dev/sdb1             107M  5.6M   96M   6% /mnt/d1
[root@localhost mnt]# e2label /dev/sdb1 lala
[root@localhost mnt]# umount d1
[root@localhost mnt]# mount -L lala d1
[root@localhost mnt]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                      8.4G  808M  7.2G  10% /
tmpfs                 250M     0  250M   0% /dev/shm
/dev/sda1             485M   30M  430M   7% /boot
/dev/sdb1             107M  5.6M   96M   6% /mnt/d1
[root@localhost mnt]#
```
# 分区加密
需要dm_crypt 模块

对改磁盘进行加密和格式化操作
[root@desktopX ~]# cryptsetup luksFormat /dev/sda5 
注意：这里会出现警告，本操作将损坏 /dev/sda5 里面的数据，我们输入大写的 YES ，
切记是大写，然后输入两遍加密密码。
设置加密磁盘为开机自动挂载：
如果希望这个映射能在开机的时候自动挂载，那么要写入 /etc/fstab 里面去，注意要使
用的是 UUID 号
[root@desktopX ~]# blkid /dev/sda5
[root@desktopX ~]# vim /etc/fstab
……
UUID=XXXXXXXXXXXXXXXX /mnt ext4 defaults 0 0
……
但这个时候系统在启动的时候，会等待你输入密码
如果希望系统启动的时候我们不需要输入密码的话，我们可以先把密码写到一个文本
文件里去，系统再启动的时候自动读取这个文件即可
[root@desktopX ~]# echo -n "redhat">/root/rhce_pw
[root@desktopX ~]# cryptsetup luksAddKey /dev/sda5 /root/rhce_pw
编辑 /etc/crypttab
[root@desktopX ~]# vim /etc/crypttab
……
写入以下内容
rhce /dev/sdb1 /root/rhce_pw

映射名   硬件名  密码文件（可以是none)

# 挂载
```
mount -t 文件系统类型 -o 选项 device dir
mount -L label_name dir  # 用label 挂载
mount -a # 按照/etc/fstab 挂载 
mount --bind /aaa /bbb  将一个目录挂载在另一个目录下
```
```
/etc/filesystems 挂载文件系统时会自动测试的文件系统类型   
/proc/filesystems 内核已经加载的文件系统类型
/lib/modules/$(uname -r)/kernel/fs/ 是否有驱动程序
/etc/mtab 每一次操作文件系统，都会动态更新/etc/mtab,当然，也可以读取/proc/mount来获取当前文件系统挂载信息
```
## /etc/fstab
```
cat /etc/fstab 
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/sda1 during installation
UUID=7383cc33-5d9c-4306-a695-735d42821ae4 /               ext4    errors=remount-ro 0       1
# /boot/efi was on /dev/nvme0n1p2 during installation
UUID=547F-0417  /boot/efi       vfat    umask=0077      0       1
/swapfile                                 none            swap    sw              0       0
```
**参数**
```
async/sync  磁盘是否随时同步数据，不同步性能更好（默认async)
auto/noauto mount -a 时是否自动挂载(默认auto)
rw/ro       只读，读写
exec/noexec 可执行，不可执行
user/nouser 普通用户能否挂载
suid/nosuid 是否开启suid 功能
usrquota    是否开启usrquota 功能
grpquota    是否开启grpquota 功能
defaults    等同于 rw, suid, dev, exec, auto, nouser, async 
```

乱读天书， 不求甚解

乱读天书，不求甚解