Shell script loop for while until and package management "on"

Shell script loop for while until and package management "on"

Loop execution

To run a code segment repeatedly multiple times

How many times to run repeatedly:

Number of cycles known beforehand

Number of cycles unknown beforehand

There are entry conditions and exit conditions

For, while, until

For variable name in list;

Loop body

Done

Execution mechanism: Assigns the element in the list to the "variable name" in turn; The loop body is executed once each assignment; Until the elements in the list are exhausted, the loop ends

List Generation Method:

(1) Give the list directly

(2) List of integers: (a) {start. End} (b) $ (SEQ [start [step]] end)

(3) command to return a list

(4) using glob, such as: *.sh

(5) variable reference; [email protected], $*

While loop

While CONDITION; Do

Loop body

Done

CONDITION: cyclic control conditions; Before entering the cycle, make a judgment; once each loop is judged again; the condition is "true", then a loop is executed until the condition test state is "false" to terminate the loop

Therefore: Condtion generally should have a cyclic control variable, and the value of this variable will be continuously corrected in the loop body

Entry condition: condition is true;

Exit Condition: Condition is false

until circulation until CONDITION; Do

Loop body

Done

Entry condition: CONDITION is False

Exit Condition: CONDITION is True

Continue and break of loop control statement

Loop Control statement Continue

Used in the loop body

Continue [n]: End of the nth layer of the current cycle, and directly into the next round of judgment; the inner layer is the 1th floor.

While CONDTIITON1; Do

CMD1

...

if CONDITION2; Then

Continue

Fi

Cmdn

...

Done

Loop control Statement Break

Used in the loop body

Break [n]: Early end of the nth layer cycle, the inner layer is the 1th layer

While CONDTIITON1; Do

CMD1

...

if CONDITION2; Then

Break

Fi CMDN

...

Done

Create an infinite loop

While true; Do

Loop body

Done

until false; Do

Loop body

Done

Unzip the archived tar

tar [OPTION] ...

(1) Create an archive

Tar-c-f/path/to/somefile.tar FILE ...

Tar Cf/path/to/somefile.tar FILE ...

(2) View the list of files in the archive file

Tar-t-f/path/to/somefile.tar

(3) Expand archive

Tar-x-f/path/to/somefile.tar tar-x-f/path/to/somefile.tar-c/path/

Combined with compression tool implementation: Archive and Compress-j:bzip2,-z:gzip,-J:XZ

Cpio copying from or to a file

The Cpio command is a redirected way of packaging a file for backup, restoring a recovery tool that can decompress files ending with ". Cpio" or ". Tar".

cpio [Options] > file name or device name

Cpio [Options] < file name or device name

Options

-o Package a file copy into a file or export the file to the device

-I unpack, unzip the package file or restore the backup on the device to the system

-T Preview, view the contents of the file or output to the file on the device

-V Displays the file name during the packaging process.

-D Unpack the directory, and automatically build the directory when Cpio restore

-C A newer storage method

For example

To back up the ETC directory:

Find./etc-print |cpio-ov >etc.cpio

Content Preview

Cpio–tv < Etc.cpio

To unpack a file

Cpio–iv <etc.cpio

Cpio–idv < Etc.cpio

Software operating Environment

Api:application Programming Interface

Posix:portable OS

Program Source--preprocessing----compile-to-link

Static compilation:

Shared compilation:. So

Abi:application Binary Interface

Windows is incompatible with Linux

ELF (Executable and linkable Format)

PE (Portable executable)

Library-level virtualization:

Linux:wine

Windows:cywin

Package Manager

Components of a binary application:

binary files, library files, configuration files, Help files

Package Manager:

Debian:deb file, dpkg Package Manager

redhat:rpm file, RPM Package Manager

Rpm:redhat Package Manager

RPM Package Manager

Package naming

RPM Package Naming method:

name-version-release.arch.rpm

VERSION:

Major.

Minor.

Release

Release:release. OS

Common arch:x86:i386, i486, i586, i686 x86_64:x64, x86_64, AMD64

Powerpc:ppc

Platform agnostic: Noarch

Package Naming and tools

Package: Sorting and unpacking application-version-arch.rpm:

Main package application-devel-version-arch.rpm

Development sub-Package application-utils-version-arhc.rpm

Other sub-packages application-libs-version-arhc.rpm

Other sub-packages

Between packages: There may be dependencies, or even cyclic dependencies

To resolve the dependency package management tool:

YUM:RPM Package Manager Front-end tools

Apt-get:deb Package Manager Front End Tool

RPM front-end management tools on Zypper:suse

Dnf:fedora + RPM Package Manager front-end management tool

Library files

To view the library files that the binaries depend on:

Ldd/path/to/binary_file

Manage and view the library files that are loaded natively:

Ldconfig

/sbin/ldconfig-p: Displays all available library files that have been cached by this computer

Name and file path mapping relationship

Configuration files:/etc/ld.so.conf,/etc/ld.so.conf.d/*.conf

Cache files:/etc/ld.so.cache

Package Manager

Package Manager: Features: Package files are packaged in one or several package files for easy and quick implementation of package installation, uninstallation, query, upgrade, and checksum management operations

1. package file composition (unique for each package)

The files in the RPM package

RPM metadata, such as name, version, dependency, description, etc.

Scripts to run when installing or uninstalling

2. Database (public)

Package Name and version

Dependent relationships

Function description

File path and checksum information generated after package installation

How to manage Packages:

Using Package Manager:

Rpm

Using the front-end tool:

Yum, DNF

RPM Package Management

Using the RPM command management package on the CentOS system:

Installation, uninstallation, upgrade, query, checksum, database maintenance

Installation:

RPM {-i|--install} [install-options] package_file ...

-v:verbose

-VV:

-H: Show package Management execution progress with #

RPM-IVH Package_file ...

RPM package installation [Install-options]

--test: Test installation, but do not actually perform installation; dry run mode

--nodeps: Ignoring dependencies

--replacepkgs | Replacefiles

--nosignature: Does not check the legitimacy of the source

--nodigest: Package integrity is not checked

--noscipts: Do not execute Package script fragment

%pre: Pre-installation;--nopre

%post: Post-installation script;--nopost

%preun: Unloading the forefoot;--nopreun

%postun: Post-uninstall script;--nopostun

RPM Package Upgrade

Upgrade:

RPM {-u|--upgrade} [install-options] package_file ...

RPM {-f|--freshen} [install-options] package_file ...

Upgrade: Install an older version of the package, then "Upgrade" if there is no legacy package, the "install"

Freshen: Install an older version of the package, "upgrade" if there is no legacy package, do not perform the upgrade operation

RPM-UVH Package_file ...

RPM-FVH Package_file ...

--oldpackage: Downgrade

--force: Forced escalation

Upgrade considerations

(1) Do not upgrade the kernel, Linux supports multi-core version coexistence, therefore, the direct installation of the new version of the kernel

(2) If the original package configuration file has been modified after installation, the new version of the upgrade

The same profile provided does not directly overwrite the old version of the configuration file, and the new version of the file is renamed (filename.rpmnew) after the retention

1. The sum of all positive integers within 100

#!/bin/bash

Read-p "First Number:" A

Read-p "second number:" B

[$a-ge $b] && echo "sum is" seq-s+ $b $a | BC ' "| | echo "Sum is" seq-s+ $a $b | BC ' "

[Email protected] bin]# bash shushu.sh

First Name is A:2

Second name is b:100

sum= 5049

2, through the ping command to detect the 172.16.250.1-254 range of all the host's online status, statistics online host and the number of offline host.

#!/bin/bash

Read-p "Please input a IPv4:" IP

Up=0 down=0

Ipv4= ' echo $ip |cut-d.-f1-3 '

For IPV in {0..255};d o

ip= "$IPV 4". " $IPV "

Ping "$IP"-C 1-w 1 &>/dev/null && echo "The Up IPv4 are: $IP" && let up+=1 &>/dev/null | | Let Down+=1 &>/dev/null

Done

echo "IPv4 ($IPV 4.1-255) up is: $up"

echo "IPv4 ($IPV 4.1-255) down is: $down"

3. Print 99 multiplication table

For i in {1..9};d o

For j in $ (seq 1 $i);d o

Echo-ne "${j}x${i}=$[i*j]\t"

Done

Echo

Done

Computer Demo

[Email protected] bin]# vim 999.sh

[Email protected] bin]# bash 999.sh

1x1=1

1x2=22x2=4

1x3=32x3=63x3=9

1x4=42x4=83x4=124x4=16

1x5=52x5=103x5=154x5=205x5=25

1x6=62x6=123x6=184x6=245x6=306x6=36

1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49

1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64

1x9=92x9=183x9=274x9=365x9=456x9=547x9=638x9=72 9x9=81

4. Generate 10 random numbers using variable random, output this 10 number, and show the largest and smallest of them

#!/bin/bash

Declare-i max=0

Declare-i min=0

For i in {1..10};d o

tmp= $RANDOM

[$i-eq 1] && min= $tmp

If [$i-le 9]; then

Echo-n "$tmp"

Else

echo "$tmp"

Fi

If [$tmp-gt $max]; then

max= $tmp

elif [$tmp-lt $min]; then

min= $tmp

Fi

Done

echo "The Max Random is $max"

echo "The min Random is $min"

5. Print Chess board

1#!

2 #

3 for I in $ (SEQ 1 8);d O

4 for J in $ (SEQ 1 8);d O

5 [$[i%2-$j%2]-eq 0] && echo-ne "\033[41m \033[0m" | | Echo-ne "\033[47 m \033[0m"

6 Let J + +

7 Done

8 echo ""

9 Let i++

Ten done

11

Shell script loop for while until and package management "on"