linux解决bash: nc: command not found 安装nc、telnet、yum

迷南。 2022-03-24 15:20 2338阅读 0赞

一、最近在用zookeeper搭建集群改造配置中心的单点故障问题：使用"四字命令"echo ruok|nc localhost 2181时报错：发现命令无法被识别：

\[root@centos6 bin\]\# echo ruok|nc localhost 2181  
\-bash: nc: command not found  
从提示信息中我们可以知道，是由于nc命令无法被找到。出现该情况有两种可能：

（1）没有配置nc命令的环境变量；  
（2）该系统没有安装nc命令；

我查看了一下在/usr/bin目录中并没有nc命令，所以我可以认为出现该情况的原因是第二种情况

二、安装  
2.1、配置yum

yum是一种在线安装和更新软件的工具，使用该工具要保证网络连接，还要有一个可用的软件源，可以使用163或sohu的软件源，软件源地址如下：

a：163的网址：http://mirrors.163.com/ ，进入后点击右列的“fedora使用帮助”，有使用说明  
b：sohu的网址：http://mirrors.sohu.com/  
c: Centos自带的源

在此我使用的是163的源，使用163下载源，则步骤如下：

a：下载fedora-163.repo和fedora-updates-163.repo, 通过winCP放入Linux中/etc/yum.repos.d/目录  
b：运行以下命令生成缓存：**yum clean all、yum makecache**

2.2、执行yum install -y nc在线安装nc

\[root@centos6 bin\]\# yum install -y nc

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMzI2NDQ5_size_16_color_FFFFFF_t_70][]

再次执行nc命令可得状态信息

\# 再次执行 echo stat | nc localhost 2181  
\[root@centos6 bin\]\# echo stat | nc localhost 2181  
Zookeeper version: 3.4.10-39d3a4f269333c922ed3db283be479f9deacaa0f, built on 03/23/2017 10:13 GMT  
Clients:  
 /0:0:0:0:0:0:0:1:55071\[0\](queued=0,recved=1,sent=0)  
   
Latency min/avg/max: 0/0/0  
Received: 1  
Sent: 0  
Connections: 1  
Outstanding: 0  
Zxid: 0xa00000001  
Mode: follower  
Node count: 5

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMzI2NDQ5_size_16_color_FFFFFF_t_70 1][]

2.3、安装远程命令telnet

执行命令：yum list telnet\*；查看telnet相关的安装包，结果如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMzMzI2NDQ5_size_16_color_FFFFFF_t_70 2][]

telnet.x86\_64表示客户端，telnet-server.x86\_64表示服务端。我们需要的是客户端，安装telnet.x86\_64即可。

执行命令 **yum install telnet.x86\_64**安装即可

\[root@centos6 bin\]\# yum install telnet.x86\_64  
Loaded plugins: fastestmirror, security  
Loading mirror speeds from cached hostfile  
 \* base: mirrors.163.com  
 \* extras: mirrors.163.com  
 \* updates: mirrors.163.com  
Setting up Install Process  
Resolving Dependencies  
\--> Running transaction check  
\---> Package telnet.x86\_64 1:0.17-48.el6 will be installed  
\--> Finished Dependency Resolution  
   
Dependencies Resolved  
   
======================================================================================================================================  
 Package                       Arch                          Version                                Repository                   Size  
======================================================================================================================================  
Installing:  
 telnet                        x86\_64                        1:0.17-48.el6                          base                         58 k  
   
Transaction Summary  
======================================================================================================================================  
Install       1 Package(s)  
   
Total download size: 58 k  
Installed size: 109 k  
Is this ok \[y/N\]: y  
Downloading Packages:  
telnet-0.17-48.el6.x86\_64.rpm                                                                                  |  58 kB     00:00       
Running rpm\_check\_debug  
Running Transaction Test  
Transaction Test Succeeded  
Running Transaction  
  Installing : 1:telnet-0.17-48.el6.x86\_64                                                                                        1/1  
  Verifying  : 1:telnet-0.17-48.el6.x86\_64                                                                                        1/1  
   
Installed:  
  telnet.x86\_64 1:0.17-48.el6                                                                                                           
   
Complete!  
验证执行命令 **telnet --help** ，如下所示安装成功  
\[root@centos6 bin\]\# telnet --help  
telnet: invalid option -- '-'  
Usage: telnet \[-8\] \[-E\] \[-L\] \[-S tos\] \[-a\] \[-c\] \[-d\] \[-e char\] \[-l user\]  
    \[-n tracefile\] \[-b hostalias \] \[-r\]  
 \[host-name \[port\]\]

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