6.1 file

In order to facilitate the transmission of files on the network , We need to package multiple files into one file （ file ）. Common archiving commands include tar and cpio, Let's talk about tar Use ,cpio Please study by yourself .
tar The grammar is as follows .

tar cvf  aa.tar  file1 file2 file3 
c Means to create an archive 
v Show archived files when creating an archive , In order to simplify the output, you can not add v Options 
f Used to specify archive files 

This sentence means to file1 、file2、file3 Archive to aa.tar in .
The suffix is generally used for archived documents tar.
Prepare first , Copy several files to the current directory , The order is as follows .

[[email protected] ~]# cp /etc/hosts /etc/passwd /etc/services .
[[email protected] ~]# ls
anaconda-ks.cfg  hosts  initial-setup-ks.cfg  passwd  services
[[email protected] ~]#

And then put hosts, passwd, services Three files are filed into one file aa.tar, The order is as follows .

[[email protected] ~]# tar cf aa.tar hosts passwd services 
[[email protected] ~]# ls
aa.tar  anaconda-ks.cfg  hosts  initial-setup-ks.cfg  passwd  services
[[email protected] ~]#

The archive here is aa.tar, Check their size , The order is as follows .

[[email protected] ~]# ls -lh passwd services hosts aa.tar 
-rw-r--r--. 1 root root 690K 8 month   10 23:33 aa.tar
-rw-r--r--. 1 root root  158 8 month   10 23:32 hosts
-rw-r--r--. 1 root root 2.6K 8 month   10 23:32 passwd
-rw-r--r--. 1 root root 677K 8 month   10 23:32 services
[[email protected] ~]#

You can see ,aa.tar The size of the file is larger than the sum of the three file sizes , Explain with tar Only archiving function , There's no compression .
From the above operations, we can see that when the archive file is created , The source file is still there , Namely the hosts、passwd、services Archive to aa.tar In the following , These three documents still exist . If you want to delete the source file after archiving , You can add –remove-files Options .
Delete aa.tar, Then archive again , The order is as follows .

[[email protected] ~]# rm -rf aa.tar 
[[email protected] ~]# tar cf aa.tar hosts passwd services --remove-files 
[[email protected] ~]# ls
aa.tar  anaconda-ks.cfg  initial-setup-ks.cfg
[[email protected] ~]#

Here you can see , Three files are archived to aa.tar Then it was deleted .
Check which files are in the archive , have access to t Options , The order is as follows .

[[email protected] ~]# tar tf aa.tar 
hosts
passwd
services
[[email protected] ~]#

Want to add a file to the archive r Options , The order is as follows .

[[email protected] ~]# tar rf aa.tar anaconda-ks.cfg 
[[email protected] ~]# tar tf aa.tar 
hosts
passwd
services
anaconda-ks.cfg
[[email protected] ~]#

Here we have anaconda-ks.cfg write in aa.tar It's in .
Unpack the archived documents , The syntax of file resolution is as follows .

tar xvf aa.tar
     here x  It means to release the file 
	v Display the files that have been unpacked , To simplify the output ,v Options can be left blank 
	f Used to specify archive files 

practice ： hold aa.tar File release , The order is as follows .

[[email protected] ~]# tar xf aa.tar 
[[email protected] ~]# ls
aa.tar  anaconda-ks.cfg  hosts  initial-setup-ks.cfg  passwd  services
[[email protected] ~]#

You can see , The default is to unfurl to the current directory , If you want to unpack to the specified directory, you need to add -C Specify the directory , Now we have to put aa.tar Unsettle to /opt Directory , The order is as follows .

[[email protected] ~]# ls /opt/
[[email protected] ~]# tar xf aa.tar -C /opt
[[email protected] ~]# ls /opt
anaconda-ks.cfg  hosts  passwd  services
[[email protected] ~]#

And then empty /opt The content in , The order is as follows .

[[email protected] ~]# rm -rf /opt/*
[[email protected] ~]# ls /opt
[[email protected] ~]#

Of course, you can only unlock aa.tar A file in , Just add the file to be de filed after the normal de filing command .
hold aa.tar Medium hosts Release the file and put it on /opt in , The order is as follows .

[[email protected] ~]# ls /opt
[[email protected] ~]# 
[[email protected] ~]# tar xf aa.tar -C /opt hosts
[[email protected] ~]# ls /opt
hosts
[[email protected] ~]#

It should be noted that , here hosts To write in -C /opt Behind .

6.2 Compress

Speak in front of the tar Just archive , There's no compression . If you want to compress, there are special tools , Include gzip、bzip2、zip.
First create a test file , The order is as follows .

[[email protected] ~]# dd if=/dev/zero of=file bs=1M count=100
 Recorded 100+0  Read in of 
 Recorded 100+0  Write 
104857600 bytes (105 MB, 100 MiB) copied, 0.281021 s, 373 MB/s
[[email protected] ~]#

（1）if Is to read the content of where , Here is /dev/zero.
（2）of Is the file name of the composition .
（3）count Appoint zero Number of .
（4）bs Specify each zero Size , If no unit is specified, it defaults to B.
This means taking 100 Size is 1M Of /dev/zero Form a name called file The file of , this file The size of the should be 100M.

[[email protected] ~]# ls -lh file
-rw-r--r--. 1 root root 100M 8 month   10 23:48 file
[[email protected] ~]#

6.2.1 gzip Usage of

gzip Can be used as follows .

 Compress ：gzip  file , The suffix of the compressed file is gz
 decompression ：gzip  -d file.gz

Use gzip Yes file Compress , The order is as follows .

[[email protected] ~]# ls -lh file.gz 
-rw-r--r--. 1 root root 100K 8 month   10 23:48 file.gz
[[email protected] ~]#

You can see ,file original 100M, Compressed into file.gz The size of 100K, Of course, because file The file is too simple, so the compression ratio is very high .
use gzip hold file.gz decompression , The order is as follows .

[[email protected] ~]# gzip -d file.gz 
[[email protected] ~]#

In general ,tar and gzip Use together , Usage is as follows .

tar zcf aa.tar.gz  file1 file2 file3

stay tar Add in options z Represents a call to gzip,z and c When used together, it means compression , The suffix is usually tar.gz. The meaning of this sentence is to put file1、file2、file3 Archive and compress to aa.tar.gz in .
practice ： hold file Archive compressed to aa.tar.gz in , The order is as follows .

[[email protected] ~]# tar zcf aa.tar.gz file
[[email protected] ~]# 
[[email protected] ~]# ls -lh aa.tar.gz file
-rw-r--r--. 1 root root 100M 8 month   10 23:48 file
-rw-r--r--. 1 root root 100K 8 month   11 00:22 aa.tar.gz
[[email protected] ~]#

decompression tar.gz Format file with tar zxf aa.tar.gz.
here z Represents a call to gzip, And x When used together, it means decompression .

[[email protected] ~]# rm -rf file
[[email protected] ~]# tar zxf aa.tar.gz 
[[email protected] ~]#

6.2.2 bzip2 Usage of

bzip2 It is also a commonly used compression tool , Usage is as follows .

 Compress ： bzip2  file , The suffix of the compressed file is bz2
 decompression :   bzip2 -d file.bz2

Use bzip2 Yes file Compress , The order is as follows .

[[email protected] ~]# bzip2 file
[[email protected] ~]# ls -lh file.bz2 
-rw-r--r--. 1 root root 113 8 month   10 23:48 file.bz2
[[email protected] ~]# 

Here is the 100M Of file Can't compress 1K, Of course file The structure of is too simple, so the compression ratio is very high .
Use bzip2 unpack , The order is as follows .

[[email protected] ~]# bzip2 -d file.bz2 
[[email protected] ~]# 

In general ,tar and bzip2 Use together , Usage is as follows .

 tar jcf aa.tar.bz2  file1 file2 file3

stay tar Add in options j Represents a call to bzip2,j and c When used together, it means compression , The suffix is usually tar.bz2. The meaning of this sentence is to put file1、file2、file3 Archive and compress to aa.tar.bz2 in .

[[email protected] ~]# tar jcf aa.tar.bz2 file
[[email protected] ~]# ls -lh aa.tar.bz2 
-rw-r--r--. 1 root root 194 8 month   11 10:17 aa.tar.bz2
[[email protected] ~]#

decompression tar.bz2 Format file with tar jxf aa.tar.bz2.
here j Represents a call to bzip2, and x When used together, it means decompression .

[[email protected] ~]# rm -rf file
[[email protected] ~]# tar jxf aa.tar.bz2 
[[email protected] ~]#

6.2.3 zip Usage of

zip Is a commonly used compression tool , stay Windows It's also often used in .zip Can be used as follows .

 Compressed files :  zip aa.zip file  hold file Compress to aa.zip
 Compressed Directory ： zip -r bb.zip dir  The directory dir Compress to bb.zip in 

If you unzip zip Format of compressed files , Then use unzip, Usage is as follows .

unzip aa.zip

practice ： hold file Compress to aa.zip in , The order is as follows .

[[email protected] ~]# zip aa.zip file
  adding: file (deflated 100%)
[[email protected] ~]#
[[email protected] ~]# ls -lh file aa.zip
-rw-r--r--. 1 root root 100K 8 month   11 10:36 aa.zip
-rw-r--r--. 1 root root 100M 8 month   10 23:48 file
[[email protected] ~]#

decompression zip Format of compressed files , The order is as follows .

[[email protected] ~]# rm -rf file
[[email protected] ~]# unzip aa.zip
Archive:  aa.zip
  inflating: file                    
[[email protected] ~]#

Homework

1. There is a compressed file aa.tar.gz, Now the command to decompress him is :
   a. tar xvf aa.tar.gz
   b. tar jxf aa.tar.gz
   c. tar zxf aa.tar.gz
   d. gzip -d aa.tar.gz

2. There is a compressed file aa.tar.bz2, Now the command to decompress him is :
   a. tar xvf aa.tar.gz
   b. tar jxf aa.tar.gz
   c. tar zxf aa.tar.gz
   d. gzip -d aa.tar.gz

3. There is a compressed file figlet-2.2.4.tar.gz, Check which files are in it without unzipping , The order is ？

a. tar tf figlet-2.2.4.tar.gz
b. tar lf figlet-2.2.4.tar.gz
c. tar xf figlet-2.2.4.tar.gz
d. tar xf figlet-2.2.4.tar.gz