Linux常用命令

1、Cnetos7使用yum安装nginx

1. 查看gcc版本

   gcc -v
   

2. gcc安装命令

   yum -y install gcc
   

3. 安装openssl

   # openssl是web安全通信的基石，没有openssl，可以说我们的信息都是在裸奔。。。。。。
   yum install -y openssl openssl-devel
   

4. 安装nginx

   yum install -y nginx
   

5. 启动并设置开机自启

   sudo systemctl start nginx
   sudo systemctl enable nginx
   

2、开放防火墙端口

1. 开启防火墙

   systemctl start firewalld.service  
   

2. 关闭防火墙

   systemctl stop firewalld.service
   

3. 重启防火墙

   firewall-cmd --reload
   

4. 开启端口

   firewall-cmd --zone=public --add-port=80/tcp --permanent
   #重新加载
   firewall-cmd --reload
   

5. 查看已开放的端口

   firewall-cmd --list-ports
   

3、安装jdk

1. 解压jdk安装包

   # 解压
   tar -zxvf jdk-8u271-linux-x64.tar.gz
   # 修改解压后的文件名称为jdk1.8
   mv xxx/ jdk1.8
   

2. 配置环境变量

   vim /etc/profile
   # 在最后边加
   # JAVA环境变量
   JAVA_HOME=/xxx/xxx/xxx
   PATH=$JAVA_HOME/bin:$PATH
   CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
   export JAVA_HOME
   export PATH
   export CLASSPATH
   

3. 测试是否安装成功

   [root@iZ2ze7jmwvt3iec793aif4Z java]# java -version
   java version "1.8.0_271"
   Java(TM) SE Runtime Environment (build 1.8.0_271-b09)
   Java HotSpot(TM) 64-Bit Server VM (build 25.271-b09, mixed mode)
   [root@iZ2ze7jmwvt3iec793aif4Z java]# javac
   Usage: javac <options> <source files>
   where possible options include:
     -g                         Generate all debugging info
     -g:none                    Generate no debugging info
     -g:{lines,vars,source}     Generate only some debugging info
     -nowarn                    Generate no warnings
     -verbose                   Output messages about what the compiler is doing
     -deprecation               Output source locations where deprecated APIs are used
     -classpath <path>          Specify where to find user class files and annotation processors
     -cp <path>                 Specify where to find user class files and annotation processors
     -sourcepath <path>         Specify where to find input source files
     -bootclasspath <path>      Override location of bootstrap class files
     -extdirs <dirs>            Override location of installed extensions
     -endorseddirs <dirs>       Override location of endorsed standards path
     -proc:{none,only}          Control whether annotation processing and/or compilation is done.
     -processor <class1>[,<class2>,<class3>...] Names of the annotation processors to run; bypasses default discovery process
     -processorpath <path>      Specify where to find annotation processors
     -parameters                Generate metadata for reflection on method parameters
     -d <directory>             Specify where to place generated class files
     -s <directory>             Specify where to place generated source files
     -h <directory>             Specify where to place generated native header files
     -implicit:{none,class}     Specify whether or not to generate class files for implicitly referenced files
     -encoding <encoding>       Specify character encoding used by source files
     -source <release>          Provide source compatibility with specified release
     -target <release>          Generate class files for specific VM version
     -profile <profile>         Check that API used is available in the specified profile
     -version                   Version information
     -help                      Print a synopsis of standard options
     -Akey[=value]              Options to pass to annotation processors
     -X                         Print a synopsis of nonstandard options
     -J<flag>                   Pass <flag> directly to the runtime system
     -Werror                    Terminate compilation if warnings occur
     @<filename>                Read options and filenames from file
   

4、Linux下创建用户

1. 使用root用户登录，添加用户

   # useradd -d /为此用户设置主目录 -m 用户名
   useradd -d /xxx -m xxx
   

2. 设置密码

   [root@iZ2ze7jmwvt3iec793aif4Z shell]# passwd xxx
   Changing password for user xxx.
   New password: 
   Retype new password: 
   passwd: all authentication tokens updated successfully.
   

3. 登录测试

5、netstat的用法

1. 列出所有连接

   netstat -a
   

2. 只列出TCP或UDP协议的连接

   #列出TCP协议的连接
   netstat -at
   #列出UDP协议的连接
   netstat -au
   

3. 禁用反向域名解析，加快查询速度

   # 默认情况下 netstat 会通过反向域名解析技术查找每个 IP 地址对应的主机名。这会降低查找速度。如果你觉得 IP 地址已经足够，而没有必要知道主机名，就使用 -n 选项禁用域名解析功能。
   netstat -ant
   

4. 只列出监听中的连接

   netstat -tnl
   

5. 获取进程名、进程号以及用户id

   sudo netstat -nlpt
   

6. 打印统计数据

   # netstat 可以打印出网络统计数据，包括某个协议下的收发包数量
   # 如果想只打印出 TCP 或 UDP 协议的统计数据，只要加上对应的选项（-t 和 -u）即可
   netstat -s
   

7. 打印active状态的连接

   netstat -atnp | grep ESTA
   # 配合watch命令监视active状态的连接
   watch -d -n0 "netstat -atnp | grep ESTA"