Linux 笔记

摘要：书名跟老男孩学运维编程实战书的难点软件上解决的笔记我的本本我的台式服务器所需的准备难点对网络模式没弄懂。远程工具没用过设置整理旧笔记查找，删掉默认记法系统在前，服务在后。只有选定的进程受到保护。约秒后，进入紧急求援模式。

2016年7月毕业到现在，特不顺利，总是半途而废，损失很多时间和金钱。清单数量上二百了，障碍了。（请原谅我写作水平，但我还在努力。）

难点：对vmware网络模式没弄懂。
想法：看下来自亦是美网络，桥接设置。

[20:10:58][root@#localhost ~]# rpm -qa|grep mariadb
[20:10:59]mariadb-libs-5.5.52-1.el7.x86_64 #查找，删掉
[20:11:07][root@#localhost ~]# rpm -e --nodeps mariadb-libs-5.5.52-1.el7.x86_64
[20:11:19][root@#localhost ~]# rpm -qa|grep mysql
[20:14:32][root@#localhost ~]# mkdir /data
[20:22:32][root@#localhost ~]# wget http://repo.mysql.com/mysql57-community-release-el7-11.noarch.rpm
[20:23:15][root@#localhost ~]# rpm -ivh mysql57-community-release-el7-11.noarch.rpm 
[20:24:13][root@#localhost ~]# yum install mysql-server -y  
  
[20:29:12][root@#localhost ~]# cat /etc/my.cnf #默认
[20:29:12]# For advice on how to change settings please see
[20:29:12]# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html
[20:29:12]
[20:29:12][mysqld]
[20:29:12]#
[20:29:12]# Remove leading # and set to the amount of RAM for the most important data
[20:29:12]# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
[20:29:12]# innodb_buffer_pool_size = 128M
[20:29:12]#
[20:29:12]# Remove leading # to turn on a very important data integrity option: logging
[20:29:12]# changes to the binary log between backups.
[20:29:12]# log_bin
[20:29:12]#
[20:29:12]# Remove leading # to set options mainly useful for reporting servers.
[20:29:12]# The server defaults are faster for transactions and fast SELECTs.
[20:29:12]# Adjust sizes as needed, experiment to find the optimal values.
[20:29:12]# join_buffer_size = 128M
[20:29:12]# sort_buffer_size = 2M
[20:29:12]# read_rnd_buffer_size = 2M
[20:29:12]datadir=/var/lib/mysql
[20:29:12]socket=/var/lib/mysql/mysql.sock
[20:29:12]
[20:29:12]# Disabling symbolic-links is recommended to prevent assorted security risks
[20:29:12]symbolic-links=0
[20:29:12]
[20:29:12]log-error=/var/log/mysqld.log
[20:29:12]pid-file=/var/run/mysqld/mysqld.pid

[20:30:41][root@#localhost ~]# service mysqld status #记法：系统在前，服务在后。systemctl status xxx service xxx status

[20:30:52][root@#localhost ~]# service mysqld start
[20:31:23][root@#localhost ~]# grep "password" /var/log/mysqld.log
[20:31:23]2019-03-21T12:31:07.638261Z 1 [Note] A temporary password is generated for root@localhost: QChl.QsN9IrY
[20:31:40][root@#localhost ~]# mysql -uroot -p
[20:32:09]Enter password: 
[20:32:57]mysql> alter user "root"@"localhost" identified by "you_password"; #字母大小写，数字，符号都要！也可以设置取消复杂要求。
[20:33:13]mysql> quit;
[20:33:30][root@#localhost ~]# service mysqld restart
[20:33:58][root@#localhost ~]# mysql -uroot -p       
[20:34:04]Enter password: 
[20:34:04]Welcome to the MySQL monitor.  Commands end with ; or g.
[20:34:04]Your MySQL connection id is 2
[20:34:04]Server version: 5.7.25 MySQL Community Server (GPL)
[20:34:04]
[20:34:04]Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
[20:34:04]
[20:34:04]Oracle is a registered trademark of Oracle Corporation and/or its
[20:34:04]affiliates. Other names may be trademarks of their respective
[20:34:04]owners.
[20:34:04]
[20:34:04]Type "help;" or "h" for help. Type "c" to clear the current input statement.
[20:34:04]
[20:34:12]mysql> show databases;
[20:34:12]+--------------------+
[20:34:12]| Database           |
[20:34:12]+--------------------+
[20:34:12]| information_schema |
[20:34:12]| mysql              |
[20:34:12]| performance_schema |
[20:34:12]| sys                |
[20:34:12]+--------------------+
[20:34:12]4 rows in set (0.00 sec)
[20:34:12]
[20:34:18]mysql> quit;
[20:34:18]Bye  #注意：上面标点符号不准，csdn保存后，符号有变化!!!

[15:04:08][root@localhost ~]# yum install gcc gcc-c++ kernel-devel ncurses-devel bison cmake
[15:04:08]Loaded plugins: fastestmirror, langpacks
[15:04:08]Existing lock /var/run/yum.pid: another copy is running as pid 4258.
[15:04:08]Another app is currently holding the yum lock; waiting for it to exit...
[15:04:08]  The other application is: PackageKit
[15:04:08]    Memory : 197 M RSS (1.5 GB VSZ)
[15:04:08]    Started: Thu Mar 21 14:54:14 2019 - 09:55 ago
[15:04:08]    State  : Sleeping, pid: 4258
[15:04:10]Another app is currently holding the yum lock; waiting for it to exit...
[15:04:10]  The other application is: PackageKit
[15:04:10]    Memory : 197 M RSS (1.5 GB VSZ)
[15:04:10]    Started: Thu Mar 21 14:54:14 2019 - 09:57 ago
[15:04:10]    State  : Sleeping, pid: 4258
[15:04:11]^C
[15:04:11]Exiting on user cancel.
[15:05:01][root@localhost ~]# rm -rf /var/run/yum.pid 
[15:05:02][root@localhost ~]# yum install gcc gcc-c++ kernel-devel ncurses-devel bison cmake

[10:50:49][root@localhost ~]# hostname
[10:50:49]localhost.localdomain
[10:50:57][root@localhost ~]# cat /etc/hostname
[10:50:57]localhost.localdomain
[10:51:13][root@localhost ~]# vi /etc/hostname
[10:51:52][root@localhost ~]# cat /etc/hostname
[10:51:52]localhost
[10:51:52][root@localhost ~]# reboot

疑问：
[root@bogon ~]，这也许是默认，但装系统的时候，输入hostname后，结果还是bogon，一直计划再装一次，还是没装上，就是除了默认和不输入bogon，再试试。

[10:52:40][root@localhost ~]# vi /etc/selinux/config
[11:05:25][root@localhost ~]# cat /etc/selinux/config
[11:05:25]
[11:05:25]# This file controls the state of SELinux on the system.
[11:05:25]# SELINUX= can take one of these three values:
[11:05:25]#     enforcing - SELinux security policy is enforced. #安全策略被强制执行
[11:05:25]#     permissive - SELinux prints warnings instead of enforcing. #打印警告而不是强制执行
[11:05:25]#     disabled - No SELinux policy is loaded. #没有加载SELinux策略
[11:05:25]SELINUX=disabled
[11:05:25]# SELINUXTYPE= can take one of three two values:
[11:05:25]#     targeted - Targeted processes are protected, #有针对性的过程受到保护
[11:05:25]#     minimum - Modification of targeted policy. Only selected processes are protected.  #目标政策的最小修改。只有选定的进程受到保护。
[11:05:25]#     mls - Multi Level Security protection. #多级安全保护。
[11:05:25]SELINUXTYPE=targeted 
[11:05:25]
[10:54:03][root@localhost ~]# reboot
[11:06:54][root@localhost ~]# /usr/sbin/sestatus   # 或者 sestatus
[11:06:54]SELinux status:                 disabled
[11:07:01][root@localhost ~]# getenforce  #
[11:07:01]Disabled

[15:46:31][root@localhost ~]# setenforce 0 | 1 # 1：启用，Enforcing；0：关闭，Permissive。
[15:46:31]usage:  setenforce [ Enforcing | Permissive | 1 | 0 ] #

[08:48:03][root@#localhost ~]# cat /etc/redhat-release 
[08:48:03]CentOS Linux release 7.3.1611 (Core) 

CentOS 7.X

查看Linux版本
[root@linuxprobe ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.0 (Maipo)

rd.break方式更改root密码

重启Linux系统主机并出现引导界面时，按下e键进入内核编辑界面。

输入rd.break,位置就在fi下面，Ctrl+X。约30秒后，进入紧急求援模式。

mount -o remount,rw /sysroot
chroot /sysroot
passwd  # passwd root
touch /.autorelabel
exit
reboot

init方式修改root密码

重启Linux系统主机并出现引导界面时，按下e键进入内核编辑界面。

输入init=/bin/sh,位置就在fi下面，Ctrl+X。

mount -o remount,rw /
passwd root
touch /.autorelabel
exec /sbin/init # exec/sbin/reboot
# exit ?
# reboot ?

CentOS 6.X

重启Linux系统主机并出现引导界面时，按下e键进入内核编辑界面。

选择kernel，再按e键。

quiet结尾添加一个1或者single并回车，然后按b键，进入单用户模式。

看到Telling INIT to go to single user mode.

passwd root
New password:
Retype new password:
reboot

Ubuntu
按e键，init=/bin/bash，位置就在fi下面。

Ctrl+X。

mount -o remount,rw /
passwd # passwd root
#修改root密码
exec /sbin/reboot