配置本地yum源

1.拷贝iso到/media，并mount

[root@hadoop1 /]# cd media/
[root@hadoop1 media]# ll
total 0
[root@hadoop1 media]# scp 192.168.3.103:/backup/iso/CentOS-7-x86_64-DVD-2009.iso ./
The authenticity of host '192.168.3.103 (192.168.3.103)' can't be established.
ECDSA key fingerprint is SHA256:pustITX0EWh5ikZ4CMJKgJEhkfPQFnmi7gnfKkNMoss.
ECDSA key fingerprint is MD5:8c:9b:d4:6c:6a:08:b4:91:d3:ec:e3:ab:35:35:52:2d.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.3.103' (ECDSA) to the list of known hosts.
root@192.168.3.103's password: 
CentOS-7-x86_64-DVD-2009.iso                                                                                                                                                                                             100% 4494MB 110.2MB/s   00:40    
[root@hadoop1 media]# ll
total 4601856
-rw-r--r--. 1 root root 4712300544 Feb 12 14:16 CentOS-7-x86_64-DVD-2009.iso
[root@hadoop1 media]# mkdir iso
[root@hadoop1 media]# mount -o loop CentOS-7-x86_64-DVD-2009.iso /media/iso/
mount: /dev/loop0 is write-protected, mounting read-only
[root@hadoop1 media]# ll
total 4601858
-rw-r--r--. 1 root root 4712300544 Feb 12 14:16 CentOS-7-x86_64-DVD-2009.iso
drwxr-xr-x. 8 root root 2048 Nov 4 2020 iso

2.配置CentOS7.9.repo

[root@hadoop1 media]# cd /etc/yum.repos.d/
[root@hadoop1 yum.repos.d]# ll
total 44
-rw-r--r--. 1 root root 2523 Dec 23  2020 CentOS-Base.repo
-rw-r--r--. 1 root root 1309 Oct 23  2020 CentOS-CR.repo
-rw-r--r--. 1 root root  649 Oct 23  2020 CentOS-Debuginfo.repo
-rw-r--r--. 1 root root  314 Oct 23  2020 CentOS-fasttrack.repo
-rw-r--r--. 1 root root  630 Oct 23  2020 CentOS-Media.repo
-rw-r--r--. 1 root root 1331 Oct 23  2020 CentOS-Sources.repo
-rw-r--r--. 1 root root 8515 Oct 23  2020 CentOS-Vault.repo
-rw-r--r--. 1 root root  616 Oct 23  2020 CentOS-x86_64-kernel.repo
[root@hadoop1 yum.repos.d]# mv CentOS-Base.repo CentOS-Base.repo.bak
[root@hadoop1 yum.repos.d]# vi CentOS7.9.repo
[root@hadoop1 yum.repos.d]# cat CentOS7.9.repo 
[centos_os_repo]
name=CentOS7.9_repo
baseurl=file:///media/iso/
enabled=true
gpgcheck=false

3.验证，配置成功

[root@hadoop1 yum.repos.d]# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
repo id                                                                                                                   repo name                                                                                                                  status
centos_os_repo                                                                                                            CentOS7.9_repo                                                                                                             4,070
repolist: 4,070

yum保留安装包

1.使用yum --downloadonly，但是有限制

yum -y install --downloadonly --downloaddir=/tmp/package/ telnet
#其中--downloadonly表示仅下载不安装， --downloaddir=/tmp/package/ 表示自定义的存储目录
#如果已经安装了telnet这个指令，再去做仅下载的指令，就下载不下来了，可以换机器试试，或是试试下边的第3种方法

2.使用yum-utils，可以只下载安装包

[root@ecs--0001 ~]# yum -y install yum-utils
[root@ecs--0001 ~]# yumdownloader --destdir=/tmp/telnet/ telnet
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.tuna.tsinghua.edu.cn
 * extras: mirrors.tuna.tsinghua.edu.cn
 * updates: mirrors.tuna.tsinghua.edu.cn
telnet-0.17-66.el7.x86_64.rpm                                                                                                                                             |  64 kB  00:00:00     
[root@ecs--0001 ~]# cd /tmp/telnet/
[root@ecs--0001 telnet]# ll
total 72
-rw-r--r-- 1 root root 65932 Nov 18  2020 telnet-0.17-66.el7.x86_64.rpm