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centos安装compress压缩工具

压缩后的档案可以以 uncompress 解压。若要将数个档案压成一个压缩档，必须先将档案 tar 起来再压缩。由于 gzip 可以产生更理想的压缩比例，一般人多已改用 gzip 为档案压缩工具。

安装compress

[root@localhost ~]# yum -y install ncompress
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package ncompress.x86_64 0:4.2.4.4-3.1.el7_8 will be installed
--> Finished Dependency ResolutionDependencies Resolved============================================================================Package          Arch          Version                   Repository   Size
============================================================================
Installing:ncompress        x86_64        4.2.4.4-3.1.el7_8         base         27 kTransaction Summary
============================================================================
Install  1 PackageTotal download size: 27 k
Installed size: 35 k
Downloading packages:
ncompress-4.2.4.4-3.1.el7_8.x86_64.rpm                 |  27 kB   00:00     
Running transaction check
Running transaction test
Transaction test succeeded
Running transactionInstalling : ncompress-4.2.4.4-3.1.el7_8.x86_64                       1/1 Verifying  : ncompress-4.2.4.4-3.1.el7_8.x86_64                       1/1 Installed:ncompress.x86_64 0:4.2.4.4-3.1.el7_8                                      Complete!
[root@localhost ~]# compress -V                           #查看安装版本
ompress version: (N)compress 4.2.4.4, compiled: Tue Jun 23 15:37:14 UTC 2020
Compile options:FAST, DIRENT, REGISTERS=20 IBUFSIZ=8192, OBUFSIZ=1024, BITS=16Author version 4.2 (Speed improvement & source cleanup):Peter Jannesen  (peter@ncs.nl)Author version 4.1 (Added recursive directory compress):Dave Mack  (csu@alembic.acs.com)Authors version 4.0 (World release in 1985):Spencer W. Thomas, Jim McKie, Steve Davies,Ken Turkowski, James A. Woods, Joe Orost
[root@localhost ~]# compress -h
Unknown flag: 'h'; Usage: compress [-dfvcVr] [-b maxbits] [file ...]-d   If given, decompression is done instead.-c   Write output on stdout, don't remove original.-b   Parameter limits the max number of bits/code.-f   Forces output file to be generated, even if one already.exists, and even if no space is saved by compressing.If -f is not used, the user will be prompted if stdin is.a tty, otherwise, the output file will not be overwritten.-v   Write compression statistics.-V   Output vesion and compile options.-r   Recursive. If a filename is a directory, descendinto it and compress everything in it.

使用参数：

• c 输出结果至标准输出设备（一般指荧幕）
• f 强迫写入档案，若目的档已经存在，则会被覆盖 (force)
• v 将程序执行的讯息印在荧幕上 (verbose)
• b 设定共同字串数的上限，以位元计算，可以设定的值为 9 至 16 bits 。由于值越大，能使用的共同字串就 越多，压缩比例就越大，所以一般使用预设值 16 bits (bits)
• d 将压缩档解压缩
• V 列出版本讯息
• r 递归压缩目录下所有文件

压缩文件

将a.txt压缩为a.txt.Z文件

[root@localhost ~]# ls
a.txt
[root@localhost ~]# compress -f a.txt 
[root@localhost ~]# ls
a.txt.Z

解压文件

将刚压缩的文件解压

[root@localhost ~]# ls
a.txt.Z
[root@localhost ~]# compress -d a.txt.Z 
[root@localhost ~]# ls
a.txt

压缩目录下的文件

强制递归压缩目录使用-r递归-f压缩文件

[root@localhost ~]# ls
a.txt
[root@localhost ~]# compress -rf /root/a.txt 
[root@localhost ~]# ls
a.txt.Z