Linux 101 Hacks 第八章:系统管理任务(一:分区相关)
Linux系统方面的管理，涉及命令包括：
fdisk mke2fsk mount tune2fs mkswap useradd passwd groupadd ssh ssh-copy-id crontab mkfs rsync chkconfig iptables
系统管理相关的命令，基本都是 root 用户才有权限，这里的示例说明就不一一说明了(细心的同学会发现命令前面始终是$符号，一般情况是表示非root用户的；而如果是 # 开头的话，开起来就是注释的感觉了)
55.fdisk分区
注意：这种工具就要谨慎操作了，如果想要自己动手演示，建议找个新的硬盘或者废弃的硬盘，别把系统搞崩溃了。。。
fdisk 常用的5种方式：
n- 新建分区d- 删除已有的分区p- 打印分区信息w- 写入分区（保存）q- 退出分区工具
示例1: 创建分区
创建一个 /dev/sda1 主分区
$ fdisk /dev/sda
Command (m for help): p
Disk /dev/sda: 287.0 GB, 287005343744 bytes
255 heads, 63 sectors/track, 34893 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
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 (1-34893, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-34893,
default 34893):
Using default value 34893
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
示例2: 确认分区已经创建成功
$ fdisk /dev/sda
Command (m for help): p
Disk /dev/sda: 287.0 GB, 287005343744 bytes
255 heads, 63 sectors/track, 34893 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 34893 280277991 83 Linux
Command (m for help): q
更多: 7 Linux fdisk Command Examples to Manage Hard Disk Partition
56.mke2fsk分区格式化
磁盘分区过后并不能直接使用，而是需要先格式化。如果在这个阶段查看磁盘信息，将会得到错误的信息
$ tune2fs -l /dev/sda1
tune2fs 1.35 (28-Feb-2004)
tune2fs: Bad magic number in super-block while trying to
open /dev/sda1
Couldn't find valid filesystem superblock.
使用 mke2fs 分区：
$ mke2fs /dev/sda1
参数:
-m 0- root用户存储块比例，默认为：5%，这里设置为0-b 4096- 存储块大小（字节），有效值为：1024，2048，4096
$ mke2fs -m 0 -b 4096 /dev/sda1
mke2fs 1.35 (28-Feb-2004)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
205344 inodes, 70069497 blocks
0 blocks (0.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=71303168
2139 block groups
32768 blocks per group, 32768 fragments per group
96 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736,
1605632, 2654208, 4096000, 7962624, 11239424, 20480000,
23887872
Writing inode tables: done
Writing superblocks and filesystem accounting information:
done
This filesystem will be automatically checked every 32
mounts or 180 days, whichever comes first. Use tune2fs -c
or -i to override.
以上为创建 ext2 文件系统，这个基本很少用了，目前大多应该是 ext3 文件系统的：
$ mkfs.ext3 /dev/sda1
# 或者
$ mke2fs –j /dev/sda1
57.mount挂载分区
分区格式化完成后，需要挂载到系统对应的文件夹中来使用 创建文件夹后进行挂载
$ mkdir /home/database
$ mount /dev/sda1 /home/database
如果想重启系统后进行自动挂载，可以在 /etc/fstab 入口进行设置：
$ /dev/sda1 /home/database ext3 defaults 0 2
58.使用tune2fs精细化调整
使用 tune2fs –l /dev/sda1 查看文件系统：(大概是这个样子)
$ tune2fs -l /dev/sda1
tune2fs 1.41.12 (17-May-2010)
Filesystem volume name: <none>
Last mounted on: /home/database
Filesystem UUID: b904daa5-dbf8-4ba7-89f8-fd14a2d34834
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 51200
Block count: 204800
Reserved block count: 10240
Free blocks: 168949
Free inodes: 51178
First block: 1
Block size: 1024
Fragment size: 1024
Reserved GDT blocks: 256
Blocks per group: 8192
Fragments per group: 8192
Inodes per group: 2048
Inode blocks per group: 256
Flex block group size: 16
Filesystem created: Sat Jan 19 19:25:56 2013
Last mount time: Mon Aug 28 15:04:17 2017
Last write time: Mon Aug 28 15:04:17 2017
Mount count: 261
Maximum mount count: -1
Last checked: Sat Jan 19 19:25:56 2013
Check interval: 0 (<none>)
Lifetime writes: 35 MB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 128
Journal inode: 8
Default directory hash: half_md4
Directory Hash Seed: a5031479-6dde-4963-868d-55549aabd8cc
Journal backup: inode blocks
同样可以使用 tune2fs 调整 ex2/ext3 文件系统的参数，比如想修改文件系统卷名称：
$ tune2fs -l /dev/sda1 | grep volume
Filesystem volume name: /home/database
$ tune2fs -L database-home /dev/emcpowera1
tune2fs 1.35 (28-Feb-2004)
$ tune2fs -l /dev/sda1 | grep volume
Filesystem volume name: database-home
59.创建交换区文件系统
创建交换分区:
# 创建指定大小的文件
$ dd if=/dev/zero of=/home/swap-fs bs=1M count=512
512+0 records in
512+0 records out
$ ls -l /home/swap-fs
-rw-r--r-- 1 root root 536870912 Jan 2 23:13 /home/swap-fs
# 安装到交换区
$ mkswap /home/swap-fs
# 启用交换分区
$ swapon /home/swap-fs
如果想要重启的时候也生效，可以在 /etc/fstab 添加一行：
$ /home/swap-fs swap swap defaults 0 0
更多: 2 Ways to Add Swap Space Using dd, mkswap and swapon
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