/etc:linux System Configuration File
Configure the following static address parameters for the virtual machine server
– Host Name: server0.example.com
– IP Address: 172.25.0.11
– Subnet Mask: 255.255.255.0
– Default gateway: 172.25.0.254
–dns Server: 172.25.254.254
# Cat/etc/sysconfig/network-scripts/ifcfg-eth0
# cat/etc/resolv.conf
Test DNS resolution
[email protected] ~]# nslookup server0.example.com
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Building a yum Warehouse
[Email protected] ~]# rm-rf/etc/yum.repos.d/*
[Email protected] ~]# Vim/etc/yum.repos.d/abc.repo
http://172.25.254.254/content/rhel7.0/x86_64/dvd/
[email protected] ~]# Yum Clean all
[email protected] ~]# Yum repolist
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View Text file contents
Cat: Suitable for viewing files with less content
Less: Suitable for viewing files with more content
See the text file part of the content
Head-n: First few lines
Tail-n: A few lines in the tail
View Time
Date
Calculator
Bc
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Pipe: The output of the preceding command is processed by the following command as a parameter of the following command
Display/etc/passwd text content 8--12 line?
[Email protected]/]# HEAD-12/ETC/PASSWD | Tail-5
[Email protected]/]# Cat-n/etc/passwd | head-12 | Tail-5
[Email protected]/]# Cat-n/etc/passwd | Less
[Email protected]/]# echo | Bc
[Email protected]/]# echo 8*8 | Bc
[Email protected]/]# Ifconfig | Head-2
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grep: View the contents of a text file, displaying the line containing the specified string
–grep [option] ' Match string ' text file ...
[[email protected]/]# grep ' root '/etc/passwd
[[email protected]/]# grep ' man '/etc/man_db.conf
[[email protected]/]# grep ' Root '/etc/passwd
[Email protected]/]# grep-i ' Root '/etc/passwd #忽略大小写
[[email protected]/]# grep ' root '/etc/passwd
[[email protected]/]# grep-v ' root '/etc/passwd #取反, does not contain
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–^word Start with string word
–word$ End With string word
[[email protected]/]# grep ' ^root '/etc/passwd
[[email protected]/]# grep ' root$ '/etc/passwd
[[email protected]/]# grep ' bash$ '/etc/passwd
Match Blank Line
[[email protected]/]# grep ' ^$ '/etc/default/useradd
Remove blank lines, display
[Email protected]/]# grep-v ' ^$ '/etc/default/useradd
Regular expressions: To express what you think in a descriptive language
Remove comments and blank lines to show valid data:
# grep-v ' ^# '/etc/login.defs | Grep-v ' ^$ '
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Find Files by criteria
? Find the corresponding file recursively according to the preset conditions
–find [Catalogue] [condition 1]
– Common conditions indicate:
-type type (f file, D directory, L shortcut)
-name "Document Name"
-size +|-File Size (k, M, G)
-user User Name
[Email protected]/]# find/boot/-type l
[Email protected]/]# Ls/boot/grub/menu.lst
[Email protected]/]# ls-l/boot/grub/menu.lst
[Email protected]/]# find/boot/-type F
[Email protected]/]# find/boot/-type D
[Email protected]/]# find/etc/-name "passwd"
[Email protected]/]# find/etc/-name "*tab*"
[Email protected]/]# Mkdir/root/install
[Email protected]/]# Touch/root/install.log
[Email protected]/]# Touch/root/install.bak
[Email protected]/]# find/root-name "install*"
[Email protected]/]# find/root-name "install*"-type D
[Email protected]/]# find/root-name "install*"-type F
[Email protected]/]# find/boot/-size +10m
[Email protected]/]# find/boot/-size-10m
--exec operation using the Find command
–find. .. -exec processing command {} \;
# find/boot/-size +10m
# find/boot/-size +10m-exec cp-r {}/opt/\;
# ls/opt
# find/etc/-name "*tab"
# find/etc/-name "*tab"-exec cp-r {}/mnt/\;
# ls-a/mnt
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# Mkdir/root/findfiles
# Find/-user Student-type f-exec cp-r {}/root/findfiles/\;
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User and Group Management
User account:
1. Can log into the operating system
2. Access control is possible (different user rights are different)
Group accounts: Easy to manage user accounts (permissions)
User account and group account unique identifier: UID GID
The Administrator uid is: 0
Group accounts: Basic group additional groups (public group subordinate groups)
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? Using the Useradd command
–useradd [Options] ... User name
? Common Command Options
–-u User ID,-D home directory path,-s login shell
–-G Basic Group,-G additional Group
[[email protected]/]# ID NSD01
[[email protected]/]# grep ' nsd01 '/etc/passwd #用户基本信息
Nsd01:x:1002:1002::/home/nsd01:/bin/bash
User name: Password placeholder: uid:gid: User's description: Home directory: Interpreter
[Email protected]/]# Useradd nsd01
[[email protected]/]# ID NSD01
[[email protected]/]# grep ' NSD '/etc/passwd
[Email protected]/]# useradd-u 1100 nsd02 #指定UID
[[email protected]/]# grep ' NSD '/etc/passwd
[Email protected]/]# useradd-d/op/haha nsd03 #指定家目录
[[email protected]/]# grep ' NSD '/etc/passwd
Specify the Login interpreter program
[Email protected]/]# useradd-s/sbin/nologin nsd04
[[email protected]/]# grep ' NSD '/etc/passwd
Cannot log on to the operating system if the user's interpreter program is/sbin/nologin
[Email protected]/]# useradd-g nsd01 nsd09
[[email protected]/]# ID nsd09
[Email protected]/]# useradd-g nsd01 nsd10
[[email protected]/]# ID NSD10
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User password information stored in the/etc/shadow file
Using the passwd command
–passwd [user Name]
–echo ' Password ' | passwd--stdin User Name
Supplemental command: command to temporarily switch user identities
[[email protected]/]# Su-user name
[Email protected]/]# echo 123 | passwd--stdin NSD01
[Email protected]/]# echo 123 | passwd--stdin nsd02
[Email protected]/]# SU-NSD01
[Email protected] ~]$ passwd
[Email protected] ~]$ exit #退回到root
[Email protected]/]#
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Modify User Properties
? Using the Usermod command
–usermod [Options] ... User name
? Common Command Options
–-u User ID,-D home directory path,-s login shell
–-G Basic Group,
–-g additional Groups
[Email protected]/]# Useradd nsd11
[[email protected]/]# grep ' nsd11 '/etc/passwd
# usermod-u 1200-d/opt/test-s/sbin/nologin nsd11
[[email protected]/]# grep ' nsd11 '/etc/passwd
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Delete User
? Using the Userdel command
–userdel [-r] User name #并且删除家目录
Common tip: Insufficient permissions
Permission denied
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Group account Management
Add Group
Group basic information is stored in the/etc/group file
[Email protected] ~]# head-1/etc/group
root:x:0:
Group name: Password placeholder: GID: Group member list
? Using the Groupadd command
–groupadd [-G Group ID] Group name
[Email protected] ~]# Useradd Kenji
[Email protected] ~]# Useradd Tom
[Email protected] ~]# Useradd Kaka
[Email protected] ~]# Useradd Henter
[Email protected] ~]# Groupadd Tarena
[[email protected] ~]# grep ' Tarena '/etc/group
TARENA:X:1110:
Using the GPASSWD command
–GPASSWD-A User Name Group name
–GPASSWD-D User Name Group name
–gpasswd-m ' user name, user name ' group name #可以添加多个
[[email protected] ~]# grep ' Tarena '/etc/group #查看组信息
[Email protected] ~]# gpasswd-a Kenji Tarena #加入组成员
[[email protected] ~]# ID Kenji
[Email protected] ~]# gpasswd-a Tom Tarena
[[email protected] ~]# grep ' Tarena '/etc/group
[Email protected] ~]# gpasswd-a Kaka Tarena
[[email protected] ~]# grep ' Tarena '/etc/group
[Email protected] ~]# gpasswd-d Kenji Tarena #删除组成员
[[email protected] ~]# grep ' Tarena '/etc/group
[Email protected] ~]# gpasswd-m ' Kenji,henter ' Tarena
[[email protected] ~]# grep ' Tarena '/etc/group
[Email protected] ~]# gpasswd-m ' Kenji,kaka,tom,henter ' Tarena
[[email protected] ~]# grep ' Tarena '/etc/group
[Email protected] ~]# gpasswd-m ' Tarena
[[email protected] ~]# grep ' Tarena '/etc/group
Delete a group
? Using the Groupdel command
–groupdel Group Name
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Archiving and compression
1. Space saving
2. Facilitate the management of fragmented documents
? Tar Integrated Backup tool
–-c: Creating an Archive
–-x: Release Archive
–-f: Specify the archive file name
–-z,-j,-j: Calling the. gz,. bz2,. xz Format tools for processing
–-c (UPPERCASE): Specify the release location
–-t: Displays a list of files in the archive
–-p (uppercase): Keep the absolute path to the file within the archive
[Email protected] ~]# rm-rf/opt/*
[Email protected] ~]# rm-rf/mnt/*
# tar-zcf/opt/file.tar.gz/boot//ETC/PASSWD
[Email protected] ~]# ls/opt
[Email protected] ~]# tar-xf/opt/file.tar.gz-c/mnt
[Email protected] ~]# ls/mnt
[Email protected] ~]# ls/mnt/etc
[Email protected] ~]# Ls/mnt/boot
? Use tar-c ... Command
–TAR-ZCF backup files. tar.gz The document that was backed up ....
–TAR-JCF backup files. tar.bz2 The document that was backed up ....
–TAR-JCF backup files. Tar.xz The document that was backed up ....
[Email protected] ~]# tar-tf/opt/file.tar.gz
Use BZIP2 compression to package and compress in absolute path mode
# tar-pjcf/root/backup.tar.bz2/usr/local/
# ls/root/
# tar-tf/root/backup.tar.bz2 #查看包里面内容
-Z represents gzip compression format
-J represents bzip2 compression format
-j represents the XZ compression format
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NTP Network Time Protocol
? Network Time Protocol
–NTP Server provides standard time for clients
–NTP client needs to maintain communication with NTP server
Packaging, configuration, service
One, the server, Linux system on a software
NTP time synchronization server, classroom
II. client server, installing client software
? RHEL7 Client's School Time service
– Package: Chrony
– Configuration file:/etc/chrony.conf
– System Services: Chronyd
[Email protected] ~]# rpm-q chrony
Chrony-1.29.1-1.el7.x86_64
[Email protected] ~]# vim/etc/chrony.conf
#server 0.rhel.pool.ntp.org Iburst #注释
#server 1.rhel.pool.ntp.org Iburst #注释
#server 2.rhel.pool.ntp.org Iburst #注释
Server 172.25.254.254 Iburst #指定服务端IP地址
.......
[Email protected] ~]# systemctl restart Chronyd #重起服务
[Email protected] ~]# Systemctl enable Chronyd #设置开机自起
Verify:
[[Email protected] ~]# Date
[Email protected] ~]# date-s "2008-09-08 11:11:11" #修改时间
[[Email protected] ~]# Date
[[email protected] ~]# systemctl restart chronyd #重起服务, sync
[[Email protected] ~]# Date
[[Email protected] ~]# Date
[[Email protected] ~]# Date
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Linux System Learning Day Fourth
