A case study of gzip and zip compressed and decompressed by Shell command file
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1.gzip:gzip Compression tool
The functional description of the gzip command:
The gzip command is used to compress files. Gzip is a widely used compression program that compresses files with the .gz extension after their names.
The syntax format of the gzip command:
Gzip [- acdfhlLnNrtvV19] [- S suffix] [name.] gzip [- acdfhlLnNqrtvV] [- S] [-] [--best/fast] [file.] Or gzip [- acdfhlLnNqrtvV] [- S] [-] [--best/fast] [directory]
Common parameters of the gzip command are described as follows:
There are many parameters for gzip. The following are the parameters and description of the gzip command:
Explanation of parameter options
-an or-- ascii uses ASCII text mode.
-c or-- stdout or-- to-stdout outputs the compressed file to a standard output device without changing the original file.
-d or-- decompress or-uncompress unpack the compressed file.
-f or-- force forcibly compress the file. Regardless of whether the file name or hard connection exists and whether the file is a symbolic link.
-h or-- help online help.
-l or-- list lists information about the compressed file.
-L or-- license displays version and copyright information.
When-n or-- no-name compresses a file, the original file name and timestamp are not saved.
When-N or-- name compresses the file, saves the original file name and timestamp.
-Q or-- quiet does not display a warning message.
-r or-- recursive recursive processing, processing all files and subdirectories under the specified directory together.
-S or-suffix changes the compressed suffix string.
-t or-- test tests whether the compressed file is correct.
-v or-- verbose shows the instruction execution process.
-V or-- version displays version information.
-Compression efficiency is a value between 1Mui 9 and the default value is "6". The higher the specified value, the higher the compression efficiency.
-- best this parameter has the same effect as specifying the "- 9" parameter.
-- fast this parameter has the same effect as specifying the "- 1" parameter.
Practical operation of gzip command
Example 1: compressed file
[root@m01 ~] # ls displays the current directory file a.c b.h d.cpp [root@m01 ~] # gzip * all files in the compressed directory [root@w3cschool.cc a] # [root@m01 ~] # ls shows the current directory file a.c.gz b.h.gz d.cpp.gz
Example 2: follow example 1 and list the detailed information
[root@m01] # gzip-dv * extract the file and list the details a.c.gz: 0. 0%-- replaced with a.cb.h.gz: 0. 0%-- replaced with b.hd.cpp.gz: 0. 0%-- replaced with d.cpp
Example 3: follow example 1 to display the information of the compressed file
[root@m01] # gzip-l * compressed uncompressed ratio uncompressed_name 24 0 0 0% a.c 24 0 0 0% b.h 26 0 0 0% d.cpp
2. Zip: compression tool
Functional description of the zip command
The zip command is used to compress files. Zip is a widely used compression program that compresses files to produce additional compressed files with the .zip extension.
Syntax format of the zip command
Zip [- aABcdDeEfFghjklLmoqrRSTuvVwXyzcompressed $] [--longoption...] [- b path] [- n suffixes] [- t date] [- tt date] zip [- AcdDfFghjJKlLmoqrSTuvVwXyz$] [- b] [- ll] [- n] [- t] [-] [compressed file] [file.] [- I] [- x]
Common parameters of the zip command are described as follows:
There are many parameters for zip. The following are the parameters and description of the zip command:
Explanation of parameter options
-An adjusts the executable automatic unzipping file.
-b specifies the directory where the files are temporarily stored.
-c comment each compressed file.
-d removes the specified file from the compressed file.
-D the directory name is not established in the compressed file.
-f the effect of this parameter is similar to that of specifying the "- u" parameter, but not only updates the existing file, but also adds some files to the compressed file if they do not already exist in the compressed file.
-F attempts to repair a corrupted compressed file.
-g append a compressed file to an existing compressed file instead of creating a new one.
-h online help.
-I only compress files that meet the criteria.
-j saves only the file name and its contents, but does not store any directory names.
-J deletes unnecessary data in front of the compressed file.
-k uses file names in MS-DOS-compatible format.
When compressing a file, replace LF characters with LF+CR characters.
-ll replaces LF+CR characters with LF characters when compressing the file.
-L displays copyright information.
-m after compressing the file and adding the compressed file, delete the original file, that is, move the file to the compressed file.
-n does not compress files with specific suffix strings.
-o set the change time of the compressed file to the same as the file with the latest change time in the compressed file.
-Q does not show the instruction execution process.
-r Recursive processing, processing all files and subdirectories under the specified directory together.
-S contains system and hidden files.
-t sets the date of the compressed file to the specified date.
-T check that each file in the backup file is correct.
-u replace the newer file into the compressed file.
-v displays instruction execution or version information.
-V saves the file properties of the VMS operating system.
-w if the version number is in the file name, this parameter is valid only under the VMS operating system.
-x excludes eligible files when compressing.
-X does not save additional file properties.
-y saves the symbolic link directly, not the file that the connection points to. This parameter is valid only in systems such as UNIX.
-z comment the compressed file.
-$saves the volume name of the disk where the first compressed file is located.
-Compression efficiency is a value between 1 and 9.
Practical operation of zip command
Example 1: package all files and folders in the / home/html/ directory to the html.zip in the current directory:
Zip-Q-r html.zip / home/html
Example 2: if we are in the / home/html directory, we can execute the following command:
Zip-Q-r html.zip *
Example 3: delete the file a.c from the compressed file cp.zip
Zip-dv cp.zip a.c
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