压缩文件的用途与技术
例如，计算机都是以byte单位来计量的，1byte占8bit。如果存储数字1，那么1byte就会空出7bit。采用一定的计算方式，压缩这些空间可以大大降低文件存储。
Linux系统常见的压缩命令
Linux下压缩文件的扩展名有*.tar, *.tar.gz, *.tgz, *.gz, *.Z, *.bz2
扩展名用来说明压缩所采用的指令类型
- *.Z compress程序压缩的文件
- *.gz gzip程序压缩的文件
- *.bz2 bzip2程序压缩的文件
- *.tar tar打包的数据，未压缩
- *.tar.gz tar打包的数据，经gzip压缩
- *.tar.bz2 tar打包的数据，经bzip2压缩
Compress
非常旧的指令，可以忽视，gzip可以解压其压缩的*.Z文件
gzip,zcat
gzip可以解压compress，zip，gzip压缩的文件
参数：
-c：将压缩数据输出到屏幕
-d：解压缩的参数
-t：检验压缩文件的一致性
-v：显示压缩比
-#：压缩等级，-1最快但压缩比最低，-9最慢但压缩比最好，默认-6
[[email protected] tmp]# ls -l ./auto.smb -rwxr-xr-x. 1 root root 687 6月 29 21:37 ./auto.smb//压缩 [[email protected] tmp]# gzip -v ./auto.smb ./auto.smb: 37.1% -- replaced with ./auto.smb.gz [[email protected] tmp]# ls -l ./auto.smb.gz -rwxr-xr-x. 1 root root 459 6月 29 21:37 ./auto.smb.gz//解压缩[[email protected] tmp]# gzip -d ./auto.smb.g
zcat指令可以读取纯文本被压缩后的压缩文件
[[email protected] tmp]# zcat ./auto.smb.gz
#!/bin/bash
# This file must be executable to work! chmod 755!
key="$1"
opts="-fstype=cifs"
for P in /bin /sbin /usr/bin /usr/sbin
do
if [ -x $P/smbclient ]
then
SMBCLIENT=$P/smbclient
break
fi
done
[ -x $SMBCLIENT ] || exit 1
$SMBCLIENT -gNL $key 2>/dev/null| awk -v key="$key" -v opts="$opts" -F‘|‘ -- ‘
BEGIN { ORS=""; first=1 }
/Disk/ {
if (first)
print opts; first=0
dir = $2
loc = $2
# Enclose mount dir and location in quotes
# Double quote "$" in location as it is special
gsub(/\$$/, "\\$", loc);
gsub(/\&/,"\\\\&",loc)
print " \\\n\t \"/" dir "\"", "\"://" key "/" loc "\""
}
END { if (!first) print "\n"; else exit 1 }
‘
[[email protected] tmp]#
bzip2，bzcat
参数：
-c：将压缩过程的数据显示到屏幕
-d：解压缩的参数
-k：保留源文件
-z：压缩的参数
-v：显示压缩比信息
-#：压缩比，同gzip
[[email protected] tmp]# ls -l ./auto.smb -rwxr-xr-x. 1 root root 687 6月 29 21:37 ./auto.smb [[email protected] tmp]# bzip2 -kzv ./auto.smb ./auto.smb: 1.314:1, 6.090 bits/byte, 23.87% saved, 687 in, 523 out. [[email protected] tmp]# ls -l ./auto.smb.bz2 -rwxr-xr-x. 1 root root 523 6月 29 21:37 ./auto.smb.bz2
使用bzcat可以查看压缩后的文件内容
打包命令：tar
将多个文件打包成一个文件，便于多个文件的压缩
tar
tar [-j|-z] [cv] [-f 新建的文件名] filename . .. //打包与压缩
tar [-j|-z] [tv] [-f 新建的文件名] //查看文件名
tar [-j|-z] [xv] [-f 新建的文件名]
常用的指令方式如下：
压缩：tar -jcv -f filename.tar.bz2
查询：tar -jtv -f filename.tar.bz2
解压：tar -jxv -f filename.tar.bz2 -C 欲解压的目录
[[email protected] hsperfdata_wuchao]# cd /tmp [[email protected] tmp]# mkdir ./tartest [[email protected] tmp]# cd ./tartest [[email protected] tartest]# cp /var/spool/mail/root . [[email protected] tartest]# ls -l root -rw-------. 1 root root 571540 6月 30 10:40 root [[email protected] tartest]# cp /var/spool/mail/wuchao . [[email protected]t tartest]# ls -l ./wuchao -rw-r-----. 1 root root 0 6月 30 10:41 ./wuchao //压缩 [[email protected] tartest]# tar -jcv -f tartest.tar.bz2 ./root ./wuchao ./root ./wuchao //查看压缩文件 [[email protected] tartest]# tar -jtv -f tartest.tar.bz2 -rw------- root/root 571540 2016-06-30 10:40 ./root -rw-r----- root/root 0 2016-06-30 10:41 ./wuchao //解压 [[email protected] tartest]# tar -jxv -f tartest.tar.bz2 . ./root ./wuchao //解压到特定目录[[email protected] tartest]# mkdir ./t[[email protected] tartest]# tar -jxv -f ./tartest.tar.bz2 -C ./t
完整备份工具：dump
dump
用于对文件系统的备份，对某个文件系统进行dump备份后，第二次dump时可以指定备份等级，等级0表示完整备份，等级大于0表示新备份的数据只会记录与上一次较低等级相比新增或更改的文件。
使用限制：
- 当备份的数据为单一文件系统：可以使用完整的dump功能，同时备份时可以使用挂载点或设备文件名来进行备份。
- 当备份的数据只是目录，并非单一的文件系统：比如要备份/home/someone，但该目录并非单一的文件系统，此时的备份数据都要在该目录下，且只能使用level0，不支持-u参数，即无法创建/etc/dumpdates这个level备份的时间记录文件。
dump [-Suv] [-level] [-f 备份文件] 待备份数据
dump -W
参数：
-S：列出后面待备份数据需要的磁盘空间
-u：将本次dump的时间记录到/etc/dumpdates文件中
-v：将dump的文件过程显示出来
-j：加入bzip2的支持，将数据进行压缩
-level：dump等级
-f：备份后的文件
-W：列出/etc/fstab里具有dump设置的分区是否备份过
用dump备份完整的文件系统
//查看文件系统[[email protected] tartest]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 46G 5.8G 40G 13% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 656K 1.9G 1% /dev/shm tmpfs 1.9G 17M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/mapper/centos-home 23G 92M 23G 1% /home /dev/sda5 497M 213M 284M 43% /boot tmpfs 373M 28K 373M 1% /run/user/0 /dev/sda3 976M 2.6M 907M 1% /run/media/root/MyFile //查看备份/dev/sda3需要的空间 [[email protected] tartest]# dump -S /dev/sda3 53248 //进行备份，备份到/root/boot.dump文件，/run/media/root/MyFile也可以写成/dev/sda3 [[email protected] tartest]# dump -0u -f /root/boot.dump /run/media/root/MyFile DUMP: Date of this level 0 dump: Thu Jun 30 15:42:53 2016 DUMP: Dumping /dev/sda3 (/run/media/root/MyFile) to /root/boot.dump DUMP: Label: MyFile DUMP: Writing 10 Kilobyte records DUMP: mapping (Pass I) [regular files] DUMP: mapping (Pass II) [directories] DUMP: estimated 52 blocks. DUMP: Volume 1 started with block 1 at: Thu Jun 30 15:42:53 2016 DUMP: dumping (Pass III) [directories] DUMP: dumping (Pass IV) [regular files] DUMP: Closing /root/boot.dump DUMP: Volume 1 completed at: Thu Jun 30 15:42:53 2016 DUMP: Volume 1 40 blocks (0.04MB) DUMP: 40 blocks (0.04MB) on 1 volume(s) DUMP: finished in less than a second DUMP: Date of this level 0 dump: Thu Jun 30 15:42:53 2016 DUMP: Date this dump completed: Thu Jun 30 15:42:53 2016 DUMP: Average transfer rate: 0 kB/s DUMP: DUMP IS DONE //查看备份文件 [[email protected] tartest]# ls -dl /run/media/root/MyFile /root/boot.dump -rw-r--r--. 1 root root 40960 6月 30 15:42 /root/boot.dump drwx------. 5 root root 4096 6月 30 15:38 /run/media/root/MyFile //查看更新记录 [[email protected] tartest]# cat /etc/dumpdates /dev/sda3 0 Thu Jun 30 15:42:53 2016 +0800 //查看有没有任何文件系统被备份过Last dump(s) done (Dump ‘>‘ file systems): /dev/sda3 (/run/media/root/MyFile) Last dump: Level 0, Date Thu Jun 30 15:42:53 2016
备份非文件系统，即单一目录的方法：
//将目录/run/media/root/MyFile/folder1备份[[email protected] tartest]# dump -0j -f /root/fw.dump /run/media/root/MyFile/folder1 DUMP: Date of this level 0 dump: Thu Jun 30 15:59:17 2016 DUMP: Dumping /dev/sda3 (/run/media/root/MyFile (dir /folder1)) to /root/fw.dump DUMP: Label: MyFile DUMP: Writing 10 Kilobyte records DUMP: Compressing output at compression level 2 (bzlib) DUMP: mapping (Pass I) [regular files] DUMP: mapping (Pass II) [directories] DUMP: estimated 46 blocks. DUMP: Volume 1 started with block 1 at: Thu Jun 30 15:59:17 2016 DUMP: dumping (Pass III) [directories] DUMP: dumping (Pass IV) [regular files] DUMP: Closing /root/fw.dump DUMP: Volume 1 completed at: Thu Jun 30 15:59:17 2016 DUMP: 40 blocks (0.04MB) on 1 volume(s) DUMP: finished in less than a second DUMP: Date of this level 0 dump: Thu Jun 30 15:59:17 2016 DUMP: Date this dump completed: Thu Jun 30 15:59:17 2016 DUMP: Average transfer rate: 0 kB/s DUMP: Wrote 40kB uncompressed, 11kB compressed, 3.637:1 DUMP: DUMP IS DONE [[email protected] tartest]#
restore
备份后的恢复
restore -t [-f dumpfile] [-h] 用来查看dump文件
restore -C [-f dumpfile] [-D 挂载点] 用来比较dump文件与实际文件
restore -i [-f dumpfile] 进入互动模式
restore -r [-f dumpfile] 还原整个文件系统
-h：查看完整备份数据的inode和文件系统的label信息
用restore查看dump后的备份数据内容
[[email protected] tartest]# restore -t -f /root/boot.dump
Dump date: Thu Jun 30 15:42:53 2016
Dumped from: the epoch
Level 0 dump of /run/media/root/MyFile on localhost.localdomain:/dev/sda3
Label: MyFile
2 .
11 ./lost+found
12 ./Untitled Folder
8193 ./Untitled Folder 2
13 ./Untitled Folder 2/Untitled Folder
[[email protected] tartest]#
比较差异并还原整个系统
//移除原文件系统的一个文件夹 [[email protected] /]# rm -rf /run/media/root/MyFile/folder1 //查看文件系统和备份文件之间的差异 [[email protected] /]# restore -C -f /root/boot.dump Dump date: Thu Jun 30 15:42:53 2016 Dumped from: the epoch Level 0 dump of /run/media/root/MyFile on localhost.localdomain:/dev/sda3 Label: MyFile filesys = /run/media/root/MyFile restore: unable to stat ./Untitled Folder: No such file or directory Some files were modified! 1 compare errors [[email protected] /]#
还原文件系统：首先创建新的文件系统
[[email protected] /]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
...
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT
/dev/sda2 206848 403138559 201465856 7 HPFS/NTFS/exFAT
/dev/sda3 403138560 405235711 1048576 83 Linux
/dev/sda4 473042944 625141759 76049408 5 Extended
/dev/sda5 473044992 474068991 512000 83 Linux
/dev/sda6 474071040 625141759 75535360 8e Linux LVM
Command (m for help): d
Partition number (1-6, default 6): 2
Partition 2 is deleted
Command (m for help): p
...
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT
/dev/sda3 403138560 405235711 1048576 83 Linux
/dev/sda4 473042944 625141759 76049408 5 Extended
/dev/sda5 473044992 474068991 512000 83 Linux
/dev/sda6 474071040 625141759 75535360 8e Linux LVM
Command (m for help): n
Partition type:
p primary (2 primary, 1 extended, 1 free)
l logical (numbered from 5)
Select (default p): p
Selected partition 2
First sector (206848-625142447, default 206848):
Using default value 206848
Last sector, +sectors or +size{K,M,G} (206848-403138559, default 403138559): +2014M
Partition 2 of type Linux and of size 2 GiB is set
...
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT
/dev/sda2 206848 4331519 2062336 83 Linux
/dev/sda3 403138560 405235711 1048576 83 Linux
/dev/sda4 473042944 625141759 76049408 5 Extended
/dev/sda5 473044992 474068991 512000 83 Linux
/dev/sda6 474071040 625141759 75535360 8e Linux LVM
Command (m for help): w
The partition table has been altered!
[[email protected] /]# partprobe
[[email protected] /]# mkfs -t ext3 /dev/sda2
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
129024 inodes, 515584 blocks
25779 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=528482304
16 block groups
32768 blocks per group, 32768 fragments per group
8064 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912
Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
[[email protected] /]# mount /dev/sda2 /mnt
cd到新建的文件系统的挂载点
//cd到新建的文件系统的挂载点（重要）[[email protected] /]# cd /mnt//将备份文件还原到当前文件系统 [[email protected] mnt]# restore -r -f /root/fw.dump Dump tape is compressed. ./lost+found: (inode 11) not found on tape ./Untitled Folder 2: (inode 8193) not found on tape [[email protected] mnt]#
仅还原部分文件的互动模式
//查看备份文件[[email protected] mnt]# restore -t -f /root/boot.dump
Dump date: Thu Jun 30 15:42:53 2016
Dumped from: the epoch
Level 0 dump of /run/media/root/MyFile on localhost.localdomain:/dev/sda3
Label: MyFile
2 .
11 ./lost+found
12 ./Untitled Folder
8193 ./Untitled Folder 2
13 ./Untitled Folder 2/Untitled Folder
//进入restore互动模式，此时的所有操作都在备份文件内部操作
[[email protected] mnt]# restore -i -f /root/boot.dump//输入help 查看帮助
restore > help
Available commands are:
ls [arg] - list directory
cd arg - change directory
pwd - print current directory
add [arg] - add `arg‘ to list of files to be extracted
delete [arg] - delete `arg‘ from list of files to be extracted
extract - extract requested files
setmodes - set modes of requested directories
quit - immediately exit program
what - list dump header information
verbose - toggle verbose flag (useful with ``ls‘‘)
prompt - toggle the prompt display
help or `?‘ - print this list
If no `arg‘ is supplied, the current directory is used//查看备份文件列表
restore > ls
.:
Untitled Folder/ Untitled Folder 2/ lost+found/
//进入到文件夹Untitled Folder 2
restore > cd ‘Untitled Folder 2‘//查看但前目录名
restore > pwd
/Untitled Folder 2
//查看当前目录下的文件列表
restore > ls ‘Untitled Folder‘
./Untitled Folder 2/Untitled Folder:
//将Untitled Folder目录添加到解压缩列表
restore > add ‘Untitled Folder‘
//查看当前目录，要被解压的文件前面会有一个*号
restore > ls
./Untitled Folder 2:
*Untitled Folder/
//解压
restore > extract
You have not read any volumes yet.
Unless you know which volume your file(s) are on you should start
with the last volume and work towards the first.
Specify next volume # (none if no more volumes): 1
set owner/mode for ‘.‘? [yn] y
restore > q
//查看解压后的文件
[[email protected] mnt]# ls ‘Untitled Folder 2‘
Untitled Folder
[[email protected] mnt]#
光盘写入功能
光盘很少用，手头没有可供刻录的光盘，暂且不学。
其他的压缩与备份工具
暂且跳过
时间： 2024-10-16 21:58:40