1. 背景

对于初学Docker的小伙伴们，刚学会了拉取镜像，创建容器，进入容器，但却在容器内部被一些常用的Linux命令（如：vi、vim、ifconfig、netstat…）无法使用搞得焦头烂额，本文将对这些问题提出解决方案；

案例如下：

在安装好docker的前提下；

拉取的tomcat镜像如下：

[root@centos7 ~]# docker images
REPOSITORY    TAG           IMAGE ID       CREATED        SIZE
tomcat        9.0.50-jdk8   8ffa9facce42   2 weeks ago    534MB
hello-world   latest        d1165f221234   4 months ago   13.3kB

以该tomcat镜像创建一个名为tomcat-test的容器，如下：

[root@centos7 ~]# docker run -id -P --name=tomcat-test tomcat:9.0.50-jdk8
5fb32eaa3c6495d76e0896dfd6b9b589ed79081a2e20696dfab5c981846e8328
[root@centos7 ~]# docker ps -a
CONTAINER ID   IMAGE                COMMAND             CREATED          STATUS         PORTS                     NAMES
5fb32eaa3c64   tomcat:9.0.50-jdk8   "catalina.sh run"   10 seconds ago   Up 8 seconds   0.0.0.0:49153->8080/tcp   tomcat-test

进入tomcat-test容器，发现vim命令无法使用

[root@centos7 ~]# docker exec -it tomcat-test /bin/bash
root@5fb32eaa3c64:/usr/local/tomcat# vim test.txt
bash: vim: command not found

通过网上各种博客，其一说需要使用apt-get install vim命令安装vim，可结果如下：

root@5fb32eaa3c64:/usr/local/tomcat# apt-get install vim
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package vim

其二说安装之前需要使用apt-get update命令同步源的索引，再执行apt-get install vim命令安装vim，结果可能还是如此；

其三说需要更换为国内的apt源，但却没有提出通过不同镜像创建的容器, 因为容器系统的发行版不同，所以源的地址也不同，结果导致apt-get update命令执行失败；

总结

1. 因docker容器都是属于比较轻量级的，所以有些镜像对容器的系统做了很多删减的操作，导致一些常规命令无法使用属于正常现象
2. apt-get update命令可能因为网络原因失败，因为默认源是国外的地址
3. 国内有不同发行版系统的对于源地址，如阿里云，清华大学源等等，但切记一定要把容器系统发行版和版本号与源地址对应上，否则就无法成功

2. 解决方案

1. 查看容器系统发行版本

• 命令1: lsb_release -a

• 命令2: cat /etc/issue，可得具体发行版本和版本号

  root@5fb32eaa3c64:/usr/local/tomcat# cat /etc/issue
  Debian GNU/Linux 10 \n \l
  

• 命令3: cat /etc/redhat-releasex

2. 搜索国内该发行版本源地址

例如，搜索Debian发行版的阿里云的源地址，可在百度搜索Debian 官方阿里云源，注意版本号，可阿里云网站上得到如下结果：

deb http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb http://mirrors.aliyun.com/debian-security buster/updates main
deb-src http://mirrors.aliyun.com/debian-security buster/updates main
deb http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib

3. 备份/etc/apt/sources.list文件

root@5fb32eaa3c64:/usr/local/tomcat# mv /etc/apt/sources.list /etc/apt/sources.list.bak

4. 新建/etc/apt/sources.list文件，并写入国内源地址

root@5fb32eaa3c64:/usr/local/tomcat# cat >> /etc/apt/sources.list << EOF
deb http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb http://mirrors.aliyun.com/debian-security buster/updates main
deb-src http://mirrors.aliyun.com/debian-security buster/updates main
deb http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib
EOF

5. 同步

root@5fb32eaa3c64:/usr/local/tomcat# apt-get update
Get:1 http://mirrors.aliyun.com/debian buster InRelease [122 kB]
Get:2 http://mirrors.aliyun.com/debian-security buster/updates InRelease [65.4 kB]
Get:3 http://mirrors.aliyun.com/debian buster-updates InRelease [51.9 kB]
Get:4 http://mirrors.aliyun.com/debian buster-backports InRelease [46.7 kB]
Get:5 http://mirrors.aliyun.com/debian buster/non-free Sources [85.7 kB]
Get:6 http://mirrors.aliyun.com/debian buster/contrib Sources [42.5 kB]
Get:7 http://mirrors.aliyun.com/debian buster/main Sources [7836 kB]
Get:8 http://mirrors.aliyun.com/debian buster/non-free amd64 Packages [87.7 kB]
Get:9 http://mirrors.aliyun.com/debian buster/contrib amd64 Packages [50.1 kB]
Get:10 http://mirrors.aliyun.com/debian buster/main amd64 Packages [7907 kB]
Get:11 http://mirrors.aliyun.com/debian-security buster/updates/main Sources [195 kB]
Get:12 http://mirrors.aliyun.com/debian-security buster/updates/main amd64 Packages [297 kB]
Get:13 http://mirrors.aliyun.com/debian buster-updates/main Sources [16.6 kB]
Get:14 http://mirrors.aliyun.com/debian buster-updates/main amd64 Packages [15.2 kB]
Get:15 http://mirrors.aliyun.com/debian buster-backports/main Sources [479 kB]
Get:16 http://mirrors.aliyun.com/debian buster-backports/contrib Sources [5080 B]
Get:17 http://mirrors.aliyun.com/debian buster-backports/non-free Sources [9148 B]
Get:18 http://mirrors.aliyun.com/debian buster-backports/main amd64 Packages [490 kB]
Get:19 http://mirrors.aliyun.com/debian buster-backports/contrib amd64 Packages [9704 B]
Get:20 http://mirrors.aliyun.com/debian buster-backports/non-free amd64 Packages [34.4 kB]
Fetched 17.8 MB in 3s (5398 kB/s)              
Reading package lists... Done

6. 安装

root@5fb32eaa3c64:/usr/local/tomcat# apt-get install vim
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  libgpm2 vim-common vim-runtime xxd
Suggested packages:
  gpm ctags vim-doc vim-scripts
The following NEW packages will be installed:
  libgpm2 vim vim-common vim-runtime xxd
0 upgraded, 5 newly installed, 0 to remove and 2 not upgraded.
Need to get 7425 kB of archives.
After this operation, 33.8 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://mirrors.aliyun.com/debian buster/main amd64 xxd amd64 2:8.1.0875-5 [140 kB]
Get:2 http://mirrors.aliyun.com/debian buster/main amd64 vim-common all 2:8.1.0875-5 [195 kB]
Get:3 http://mirrors.aliyun.com/debian buster/main amd64 libgpm2 amd64 1.20.7-5 [35.1 kB]
Get:4 http://mirrors.aliyun.com/debian buster/main amd64 vim-runtime all 2:8.1.0875-5 [5775 kB]
Get:5 http://mirrors.aliyun.com/debian buster/main amd64 vim amd64 2:8.1.0875-5 [1280 kB]
Fetched 7425 kB in 0s (16.9 MB/s)
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously unselected package xxd.
(Reading database ... 12572 files and directories currently installed.)
Preparing to unpack .../xxd_2%3a8.1.0875-5_amd64.deb ...
Unpacking xxd (2:8.1.0875-5) ...
Selecting previously unselected package vim-common.
Preparing to unpack .../vim-common_2%3a8.1.0875-5_all.deb ...
Unpacking vim-common (2:8.1.0875-5) ...
Selecting previously unselected package libgpm2:amd64.
Preparing to unpack .../libgpm2_1.20.7-5_amd64.deb ...
Unpacking libgpm2:amd64 (1.20.7-5) ...
Selecting previously unselected package vim-runtime.
Preparing to unpack .../vim-runtime_2%3a8.1.0875-5_all.deb ...
Adding 'diversion of /usr/share/vim/vim81/doc/help.txt to /usr/share/vim/vim81/doc/help.txt.vim-tiny by vim-runtime'
Adding 'diversion of /usr/share/vim/vim81/doc/tags to /usr/share/vim/vim81/doc/tags.vim-tiny by vim-runtime'
Unpacking vim-runtime (2:8.1.0875-5) ...
Selecting previously unselected package vim.
Preparing to unpack .../vim_2%3a8.1.0875-5_amd64.deb ...
Unpacking vim (2:8.1.0875-5) ...
Setting up libgpm2:amd64 (1.20.7-5) ...
Setting up xxd (2:8.1.0875-5) ...
Setting up vim-common (2:8.1.0875-5) ...
Setting up vim-runtime (2:8.1.0875-5) ...
Setting up vim (2:8.1.0875-5) ...
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/vim (vim) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/vimdiff (vimdiff) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/rvim (rvim) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/rview (rview) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/vi (vi) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/view (view) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/ex (ex) in auto mode
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/editor (editor) in auto mode
Processing triggers for libc-bin (2.28-10) ...
Processing triggers for mime-support (3.62) ...

7. 成功

root@5fb32eaa3c64:/usr/local/tomcat# vim --help
VIM - Vi IMproved 8.1 (2018 May 18, compiled Jun 15 2019 16:41:15)

Usage: vim [arguments] [file ..]       edit specified file(s)
   or: vim [arguments] -               read text from stdin
   or: vim [arguments] -t tag          edit file where tag is defined
   or: vim [arguments] -q [errorfile]  edit file with first error
......