归档和压缩
归档,也称为打包,指的是一个文件或目录的集合,而这个集合被存储在一个文件中,因此它占用的空间是其中所有文件和目录的总和。常见的归档命令有
压缩是指利用算法将文件进行处理,已达到保留最大文件信息,而让文件体积变小的目的。由于计算机处理的信息是以二进制的形式表示的,因此,压缩软件就是把二进制信息中相同的字符串以特殊字符标记,把一个或者多个文件用压缩软件进行压缩,形成一个文件压缩包。
- 有损压缩:丢失个别的数据,对文件不会造成太大的影响。有损压缩广泛应用于动画、声音和图像文件中,典型代表就是影碟文件格式 mpeg、音乐文件格式 mp3 以及图像文件格式 jpg
- 无损压缩:压缩文件数据准确无误
- 解压缩:压缩包中的数据无法直接使用,使用前需要利用压缩工具将文件数据还原
tar和dd,而常见的压缩命令有gzip、zip、bzip2。tar 命令也可以作为压缩命令tar命令可以用于归档和解归档,使用此命令生成的归档包通常称作为tar包,以tar结尾。tar [选项] 源文件或目录通常使用-cvf作为tar命令打包的常见写法,该命令在使用时也可以不加-作为选项前缀
[panjianqiao@localhost ~]$ touch demo1
[panjianqiao@localhost ~]$ touch demo2
[panjianqiao@localhost ~]$ touch demo3
[panjianqiao@localhost ~]$ tar -cvf test.tar demo1 demo2 demo3
demo1
demo2
demo3
[panjianqiao@localhost ~]$ ls
demo1demo3DocumentsMusicPublictest.tar
demo2DesktopDownloadsPicturesTemplatesVideos
[panjianqiao@localhost ~]$ ls -l test.tar
-rw-rw-r--. 1 panjianqiao panjianqiao 10240 Jul 17 10:06 test.tar
tar [选项] 源文件或目录通常使用-xvf作为tar命令解打包到当前文件夹下,也可使用-C 目录解打包到指定目录文件夹下
[panjianqiao@localhost ~]$ tar -xvf test.tar #解打包到当前文件夹下
demo1
demo2
demo3
[panjianqiao@localhost ~]$ tar -xvf test.tar -C /tmp #解打包到tmp文件夹下
demo1
demo2
demo3
[panjianqiao@localhost ~]$ ls /tmp #由于篇幅限制,只显示相关信息
demo1
demo2
demo3
...
tar [选项] 压缩包 源文件或目录、tar [选项] 压缩包[panjianqiao@localhost ~]$ mkdir test1 test2 test3
[panjianqiao@localhost ~]$ ls -l
total 0
drwxr-xr-x. 2 panjianqiao panjianqiao 40 Jul 11 13:17 Desktop
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Documents
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Downloads
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Music
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Pictures
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Public
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Templates
drwxrwxr-x. 2 panjianqiao panjianqiao6 Jul 17 11:03 test1
drwxrwxr-x. 2 panjianqiao panjianqiao6 Jul 17 11:03 test2
drwxrwxr-x. 2 panjianqiao panjianqiao6 Jul 17 11:03 test3
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Videos
[panjianqiao@localhost ~]$ tar -zcvf test.tar.gz test1 test2 test3 #打包并压缩三个目录为gz格式
test1/
test2/
test3/
[panjianqiao@localhost ~]$ ls
DesktopDownloadsPicturesTemplatestest2test.tar.gz
DocumentsMusicPublictest1test3Videos
[panjianqiao@localhost ~]$ tar -zxvf test.tar.gz -C /tmp #在tmp文件夹下解打包压缩
test1/
test2/
test3/
[panjianqiao@localhost ~]$ ls /tmp
...
test1
test2
test3
...
zip格式文件是windows和linux系统都通用的文件格式,属于几种主流压缩格式(zip、rar)之一常见格式为
zip [选项] 压缩包名 源文件或源目录列表[panjianqiao@localhost ~]$ touch demo1 demo2 demo3
[panjianqiao@localhost ~]$ ls
demo1demo3DocumentsMusicPublicVideos
demo2DesktopDownloadsPicturesTemplates
[panjianqiao@localhost ~]$ zip -v demo.zip demo1 demo2 demo3 #显示压缩文件过程信息
adding: demo1 (in=0) (out=0) (stored 0%)
adding: demo2 (in=0) (out=0) (stored 0%)
adding: demo3 (in=0) (out=0) (stored 0%)
total bytes=0, compressed=0 -> 0% savings
[panjianqiao@localhost ~]$ ls
demo1demo3DesktopDownloadsPicturesTemplates
demo2demo.zipDocumentsMusicPublicVideos
[panjianqiao@localhost ~]$ mkdir test1 test2 test3
[panjianqiao@localhost ~]$ zip -vm test.zip test1 test2 test3 #显示压缩目录信息的同时删除源文件
adding: test1/(in=0) (out=0) (stored 0%)
adding: test2/(in=0) (out=0) (stored 0%)
adding: test3/(in=0) (out=0) (stored 0%)
total bytes=0, compressed=0 -> 0% savings
deleting directory test3 (if empty)
deleting directory test2 (if empty)
deleting directory test1 (if empty)
[panjianqiao@localhost ~]$ ls
demo1demo3DesktopDownloadsPicturesTemplatesVideos
demo2demo.zipDocumentsMusicPublictest.zip
unzip [选项] 压缩包名[panjianqiao@localhost ~]$ unzip test.zip
Archive:test.zip
creating: test1/
creating: test2/
creating: test3/
[panjianqiao@localhost ~]$ ls
demo1demo3DesktopDownloadsPicturesTemplatestest2test.zip
demo2demo.zipDocumentsMusicPublictest1test3Videos
gzip是面向压缩和解压缩文件的命令,此命令只能用于(单个)文件的压缩和解压,在对目录进行压缩时只会把目录文件夹下的子文件分别压缩,常见格式为gzip [选项] 源文件。[panjianqiao@localhost ~]$ touch demo1
[panjianqiao@localhost ~]$ touch demo2
[panjianqiao@localhost ~]$ touch demo3
[panjianqiao@localhost ~]$ gzip demo1 demo2 demo3 #分别压缩三个文件,压缩完成之后,原文件不保留
[panjianqiao@localhost ~]$ ls
demo1.gzdemo2.gzdemo3.gzDesktopDocumentsDownloadsMusicPicturesPublicTemplatesVideos
[panjianqiao@localhost ~]$ gzip -d demo1.gz demo2.gz demo3.gz #分别对三个文件进行解压缩
[panjianqiao@localhost ~]$ ls
demo1demo2demo3DesktopDocumentsDownloadsMusicPicturesPublicTemplatesVideos
[panjianqiao@localhost ~]$ tar -cvf demo.tar demo1 demo2 demo3 # 对三个文件归档
demo1
demo2
demo3
[panjianqiao@localhost ~]$ ls
demo1demo2demo3demo.tarDesktopDocumentsDownloadsMusicPicturesPublicTemplatesVideos
[panjianqiao@localhost ~]$ gzip demo.tar # 对归档后文件进行压缩
[panjianqiao@localhost ~]$ ls
demo1demo2demo3demo.tar.gzDesktopDocumentsDownloadsMusicPicturesPublicTemplatesVideos
[panjianqiao@localhost ~]$ mkdir -p test/test_in #创建目录
[panjianqiao@localhost ~]$ touch ./test/test_in/demo #在最次级目录下创建文件
[panjianqiao@localhost ~]$ ls -l
total 0
drwxr-xr-x. 2 panjianqiao panjianqiao 40 Jul 11 13:17 Desktop
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Documents
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Downloads
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Music
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Pictures
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Public
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Templates
drwxrwxr-x. 3 panjianqiao panjianqiao 21 Jul 17 20:10 test
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Videos
[panjianqiao@localhost ~]$ ls -l ./test/test_in
total 0
-rw-rw-r--. 1 panjianqiao panjianqiao 0 Jul 17 20:11 demo
[panjianqiao@localhost ~]$ gzip -rv test #压缩目录
test/test_in/demo:0.0% -- replaced with test/test_in/demo.gz #只能压缩目录下文件
gzip命令压缩过的文件,相当于gzip -dbzip2命令和gzip命令相似,只能对(单个)文件进行压缩或解压缩,压缩过的文件以.bz2为后缀。从理论上来讲bz2的算法更先进、压缩比更好,而gz的压缩时间更快。常见格式为bzip2 [选项] 源文件。[panjianqiao@localhost ~]$ touch demo1 demo2
[panjianqiao@localhost ~]$ bzip2 demo1 demo2
[panjianqiao@localhost ~]$ ls -l
total 8
-rw-rw-r--. 1 panjianqiao panjianqiao 14 Jul 17 22:04 demo1.bz2
-rw-rw-r--. 1 panjianqiao panjianqiao 14 Jul 17 22:04 demo2.bz2
drwxr-xr-x. 2 panjianqiao panjianqiao 40 Jul 11 13:17 Desktop
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Documents
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Downloads
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Music
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Pictures
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Public
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Templates
drwxr-xr-x. 2 panjianqiao panjianqiao6 Jun 30 23:22 Videos
bzip2命令压缩过的文件,相当于bzip2 -d