[root@iZbp143t3oxhfc3ar7jey0Z bin]# gem install -l redis-4.1.2.gem
ERROR:  Could not find a valid gem 'redis-4.1.2.gem' (>= 0) in any repository
[root@iZbp143t3oxhfc3ar7jey0Z bin]# gem install redis
Fetching: redis-4.1.3.gem (100%)
ERROR:  Error installing redis:
        redis requires Ruby version >= 2.3.0.

[root@iZbp143t3oxhfc3ar7jey0Z bin]# yum -y install curl
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * webtatic: us-east.repo.webtatic.com

Package curl-7.29.0-54.el7_7.2.x86_64 already installed and latest version
Nothing to do

root@iZbp143t3oxhfc3ar7jey0Z bin]# gpg2 --keyserver hkp://keys.gnupg.net --recv-keys D39DC0E3
gpg: directory `/root/.gnupg' created
gpg: new configuration file `/root/.gnupg/gpg.conf' created
gpg: WARNING: options in `/root/.gnupg/gpg.conf' are not yet active during this run
gpg: keyring `/root/.gnupg/secring.gpg' created
gpg: keyring `/root/.gnupg/pubring.gpg' created
gpg: requesting key D39DC0E3 from hkp server keys.gnupg.net
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: key D39DC0E3: public key "Michal Papis (RVM signing) <[email protected]>" imported
gpg: key D39DC0E3: public key "Totally Legit Signing Key <[email protected]>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 2
gpg:               imported: 2  (RSA: 2)

[root@iZbp143t3oxhfc3ar7jey0Z bin]# curl -L get.rvm.io | bash -s stable
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   194  100   194    0     0     66      0  0:00:02  0:00:02 --:--:--    66
100 24535  100 24535    0     0   6979      0  0:00:03  0:00:03 --:--:--  6979
Downloading https://github.com/rvm/rvm/archive/1.29.10.tar.gz
Downloading https://github.com/rvm/rvm/releases/download/1.29.10/1.29.10.tar.gz.asc
gpg: Signature made Thu 26 Mar 2020 05:58:42 AM CST using RSA key ID 39499BDB
gpg: Can't check signature: No public key
GPG signature verification failed for '/usr/local/rvm/archives/rvm-1.29.10.tgz' - 'https://github.com/rvm/rvm/releases/download/1.29.10/1.29.10.tar.gz.asc'! Try to install GPG v2 and then fetch the public key:

    gpg2 --keyserver hkp://pool.sks-keyservers.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB

or if it fails:

    command curl -sSL https://rvm.io/mpapis.asc | gpg2 --import -
    command curl -sSL https://rvm.io/pkuczynski.asc | gpg2 --import -

In case of further problems with validation please refer to https://rvm.io/rvm/security

[root@iZbp143t3oxhfc3ar7jey0Z bin]#  gpg2 --keyserver hkp://pool.sks-keyservers.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB
gpg: requesting key D39DC0E3 from hkp server pool.sks-keyservers.net
gpg: requesting key 39499BDB from hkp server pool.sks-keyservers.net
gpg: key D39DC0E3: "Michal Papis (RVM signing) <[email protected]>" not changed
gpg: key 39499BDB: "Piotr Kuczynski <[email protected]>" not changed
gpg: Total number processed: 2
gpg:              unchanged: 2

[root@iZbp143t3oxhfc3ar7jey0Z bin]# gem sources --add https://gems.ruby-china.com/ --remove https://rubygems.org/
https://gems.ruby-china.com/ added to sources
https://rubygems.org/ removed from sources

[root@iZbp143t3oxhfc3ar7jey0Z bin]# curl -sSL https://get.rvm.io | bash -s stable
Downloading https://github.com/rvm/rvm/archive/1.29.10.tar.gz
Downloading https://github.com/rvm/rvm/releases/download/1.29.10/1.29.10.tar.gz.asc
gpg: Signature made Thu 26 Mar 2020 05:58:42 AM CST using RSA key ID 39499BDB
gpg: Good signature from "Piotr Kuczynski <[email protected]>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 7D2B AF1C F37B 13E2 069D  6956 105B D0E7 3949 9BDB
GPG verified '/usr/local/rvm/archives/rvm-1.29.10.tgz'
Creating group 'rvm'
Installing RVM to /usr/local/rvm/
Installation of RVM in /usr/local/rvm/ is almost complete:

  * First you need to add all users that will be using rvm to 'rvm' group,
    and logout - login again, anyone using rvm will be operating with `umask u=rwx,g=rwx,o=rx`.

  * To start using RVM you need to run `source /etc/profile.d/rvm.sh`
    in all your open shell windows, in rare cases you need to reopen all shell windows.
  * Please do NOT forget to add your users to the rvm group.
     The installer no longer auto-adds root or users to the rvm group. Admins must do this.
     Also, please note that group memberships are ONLY evaluated at login time.
     This means that users must log out then back in before group membership takes effect!
Thanks for installing RVM ????
Please consider donating to our open collective to help us maintain RVM.

????  Donate: https://opencollective.com/rvm/donate

...
To start using RVM you need to run `source /etc/profile.d/rvm.sh`
....

[root@iZbp143t3oxhfc3ar7jey0Z bin]# source /etc/profile.d/rvm.sh

[root@iZbp143t3oxhfc3ar7jey0Z bin]# rvm list known
# MRI Rubies
[ruby-]1.8.6[-p420]
[ruby-]1.8.7[-head] # security released on head
[ruby-]1.9.1[-p431]
[ruby-]1.9.2[-p330]
[ruby-]1.9.3[-p551]
[ruby-]2.0.0[-p648]
[ruby-]2.1[.10]
[ruby-]2.2[.10]
[ruby-]2.3[.8]
[ruby-]2.4[.9]
[ruby-]2.5[.7]
[ruby-]2.6[.5]
[ruby-]2.7[.0]
ruby-head

 rvm list known

rvm install 2.4.2

[root@iZbp143t3oxhfc3ar7jey0Z bin]# rvm list
=* ruby-2.4.2 [ x86_64 ]

# => - current
# =* - current && default
#  * - default

[root@iZbp143t3oxhfc3ar7jey0Z bin]# 

rvm remove 1.9.2

[root@iZbp143t3oxhfc3ar7jey0Z bin]# rvm 2.4.2  --default
Using /usr/local/rvm/gems/ruby-2.4.2
[root@iZbp143t3oxhfc3ar7jey0Z bin]# 

[root@iZbp143t3oxhfc3ar7jey0Z bin]# ruby -v
ruby 2.4.2p198 (2017-09-14 revision 59899) [x86_64-linux]
[root@iZbp143t3oxhfc3ar7jey0Z bin]# gem -v
3.0.8
[root@iZbp143t3oxhfc3ar7jey0Z bin]#

$ gem source -r https://rubygems.org/
$ gem source -a https://gems.ruby-china.com/

[root@iZbp143t3oxhfc3ar7jey0Z bin]# gem sources -l
*** CURRENT SOURCES ***

https://gems.ruby-china.com/
[root@iZbp143t3oxhfc3ar7jey0Z bin]#