这是如何在CentOS 7 Linux系统上安装PHP 7.4的简短教程。
PHP 7.4.0版已在开发人员稳定阶段发布，并为用户进行测试。

第1步：添加epel和remi存储库

运行以下命令以添加所需的存储库。

sudo yum -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
sudo yum -y install https://rpms.remirepo.net/enterprise/remi-release-7.rpm

第2步：在CentOS 7上安装PHP 7.4

我们现在可以启用PHP 7.4 REMI存储库并在CentOS 7上安装PHP 7.4.

sudo yum -y install yum-utils
sudo yum-config-manager --enable remi-php74

在CentOS 7上安装PHP 7.4.

sudo yum update
sudo yum install php php-cli

接受安装提示。

Dependencies Resolved
===================================================================================================================================================
 Package                            Arch                         Version                                    Repository                        Size
===================================================================================================================================================
Installing:
 php                                x86_64                       7.4.0-1.el7.remi                           remi-php74                       3.4 M
 php-cli                            x86_64                       7.4.0-1.el7.remi                           remi-php74                       5.1 M
Installing for dependencies:
 apr                                x86_64                       1.4.8-5.el7                                base                             103 k
 apr-util                           x86_64                       1.5.2-6.el7                                base                              92 k
 centos-logos                       noarch                       70.0.6-3.el7.centos                        base                              21 M
 httpd                              x86_64                       2.4.6-90.el7.centos                        base                             2.7 M
 httpd-tools                        x86_64                       2.4.6-90.el7.centos                        base                              91 k
 mailcap                            noarch                       2.1.41-2.el7                               base                              31 k
 php-common                         x86_64                       7.4.0-1.el7.remi                           remi-php74                       1.1 M
 php-json                           x86_64                       7.4.0-1.el7.remi                           remi-php74                        68 k
Transaction Summary
===================================================================================================================================================
Install  2 Packages (+8 Dependent packages)
Total download size: 34 M
Installed size: 73 M
Is this ok [y/d/N]: y
Downloading packages:
(1/10): httpd-tools-2.4.6-90.el7.centos.x86_64.rpm                                                                          |  91 kB  00:00:00     
(2/10): apr-1.4.8-5.el7.x86_64.rpm                                                                                          | 103 kB  00:00:01     
(3/10): mailcap-2.1.41-2.el7.noarch.rpm                                                                                     |  31 kB  00:00:00     
(4/10): apr-util-1.5.2-6.el7.x86_64.rpm                                                                                     |  92 kB  00:00:01     
(5/10): httpd-2.4.6-90.el7.centos.x86_64.rpm        | 2.7 MB   00:09     warning: /var/cache/yum/x86_64/7/remi-php74/packages/php-common-7.4.0-1.el7.remi.x86_64.rpm: Header V4 DSA/SHA1 Signature, key ID 00f97f56: NOKEY
Public key for php-common-7.4.0-1.el7.remi.x86_64.rpm is not installed
(6/10): php-common-7.4.0-1.el7.remi.x86_64.rpm      | 1.1 MB   00:09     
(7/10): php-json-7.4.0-1.el7.remi.x86_64.rpm        |  68 kB   00:01     
(8/10): php-7.4.0-1.el7.remi.x86_64.rpm             | 3.4 MB   00:13     
(9/10): php-cli-7.4.0-1.el7.remi.x86_64.rpm         | 5.1 MB   00:13     
(10/10): centos-logos-70.0.6-3.el7.centos.noarch.rp |  21 MB   00:31     
------------------------------------------------------------------------
Total                                       1.1 MB/s |  34 MB  00:31     
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-remi
Importing GPG key 0x00F97F56:
 Userid     : "Remi Collet <Hyman@theitroad>"
 Fingerprint: 1ee0 4cce 88a4 ae4a a29a 5df5 004e 6f47 00f9 7f56
 Package    : remi-release-7.7-1.el7.remi.noarch (installed)
 From       : /etc/pki/rpm-gpg/RPM-GPG-KEY-remi
Is this ok [y/N]: y

使用下一个命令安装其他包：

sudo yum install php-xxx

例子：

sudo yum install php  php-cli php-fpm php-mysqlnd php-zip php-devel php-gd php-mcrypt php-mbstring php-curl php-xml php-pear php-bcmath php-json

当前的PHP版本应为7.4.

$php -v
PHP 7.4.0 (cli) (built: Nov 26 2019 20:13:36) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies

要查看启用的模块，请运行：

$php --modules