因为我正在尝试从PHP 7.2.X版本加载mcrypt扩展模块。 所以我尝试使用与我当前版本的PHP兼容的PECL库，以便安装并遵循以下链接：Installing mcrypt on PHP 7.2在安装过程中！
以下是在终端上执行某些命令后获得的结果。
root@YYY:/var/www/html/orocrm# apt install php-pear
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following package was automatically installed and is no longer required:
libllvm4.0
Use 'sudo apt autoremove' to remove it.
The following NEW packages will be installed:
php-pear
0 upgraded, 1 newly installed, 0 to remove and 14 not upgraded.
Need to get 285 kB of archives.
After this operation, 2,107 kB of additional disk space will be used.
Get:1 http://ppa.launchpad.net/ondrej/php/ubuntu xenial/main amd64 php-pear all 1:1.10.5+submodules+notgz-1+ubuntu16.04.1+deb.sury.org+1 [285 kB]
Fetched 285 kB in 1s (230 kB/s)
Selecting previously unselected package php-pear.
(Reading database ... 215503 files and directories currently installed.)
Preparing to unpack .../php-pear_1%3a1.10.5+submodules+notgz-1+ubuntu16.04.1+deb.sury.org+1_all.deb ...
Unpacking php-pear (1:1.10.5+submodules+notgz-1+ubuntu16.04.1+deb.sury.org+1) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up php-pear (1:1.10.5+submodules+notgz-1+ubuntu16.04.1+deb.sury.org+1) ...
YYY@YYY:/var/www/html/orocrm$ sudo apt-get -y install gcc make autoconf libc-dev pkg-config
[sudo] password for YYY:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'libc6-dev' instead of 'libc-dev'
gcc is already the newest version (4:5.3.1-1ubuntu1).
make is already the newest version (4.1-6).
pkg-config is already the newest version (0.29.1-0ubuntu1).
libc6-dev is already the newest version (2.23-0ubuntu9).
The following package was automatically installed and is no longer required:
libllvm4.0
Use 'sudo apt autoremove' to remove it.
Suggested packages:
autoconf-archive gnu-standards autoconf-doc libtool
The following NEW packages will be installed:
autoconf automake autotools-dev libsigsegv2 m4
0 upgraded, 5 newly installed, 0 to remove and 14 not upgraded.
Need to get 1,079 kB of archives.
After this operation, 3,998 kB of additional disk space will be used.
Get:1 http://in.archive.ubuntu.com/ubuntu xenial/main amd64 libsigsegv2 amd64 2.10-4 [14.1 kB]
Get:2 http://in.archive.ubuntu.com/ubuntu xenial/main amd64 m4 amd64 1.4.17-5 [195 kB]
Get:3 http://in.archive.ubuntu.com/ubuntu xenial/main amd64 autoconf all 2.69-9 [321 kB]
Get:4 http://in.archive.ubuntu.com/ubuntu xenial/main amd64 autotools-dev all 20150820.1 [39.8 kB]
Get:5 http://in.archive.ubuntu.com/ubuntu xenial/main amd64 automake all 1:1.15-4ubuntu1 [510 kB]
Fetched 1,079 kB in 2s (447 kB/s)
Selecting previously unselected package libsigsegv2:amd64.
(Reading database ... 215198 files and directories currently installed.)
Preparing to unpack .../libsigsegv2_2.10-4_amd64.deb ...
Unpacking libsigsegv2:amd64 (2.10-4) ...
Selecting previously unselected package m4.
Preparing to unpack .../archives/m4_1.4.17-5_amd64.deb ...
Unpacking m4 (1.4.17-5) ...
Selecting previously unselected package autoconf.
Preparing to unpack .../autoconf_2.69-9_all.deb ...
Unpacking autoconf (2.69-9) ...
Selecting previously unselected package autotools-dev.
Preparing to unpack .../autotools-dev_20150820.1_all.deb ...
Unpacking autotools-dev (20150820.1) ...
Selecting previously unselected package automake.
Preparing to unpack .../automake_1%3a1.15-4ubuntu1_all.deb ...
Unpacking automake (1:1.15-4ubuntu1) ...
Processing triggers for install-info (6.1.0.dfsg.1-5) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for doc-base (0.10.7) ...
Processing 1 added doc-base file...
Setting up libsigsegv2:amd64 (2.10-4) ...
Setting up m4 (1.4.17-5) ...
Setting up autoconf (2.69-9) ...
Setting up autotools-dev (20150820.1) ...
Setting up automake (1:1.15-4ubuntu1) ...
update-alternatives: using /usr/bin/automake-1.15 to provide /usr/bin/automake (automake) in auto mode
Processing triggers for libc-bin (2.23-0ubuntu9) ...
YYY@YYY:/var/www/html/orocrm$ sudo apt-get -y install libmcrypt-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following package was automatically installed and is no longer required:
libllvm4.0
Use 'sudo apt autoremove' to remove it.
The following NEW packages will be installed:
libmcrypt-dev
0 upgraded, 1 newly installed, 0 to remove and 14 not upgraded.
Need to get 83.7 kB of archives.
After this operation, 438 kB of additional disk space will be used.
Get:1 http://in.archive.ubuntu.com/ubuntu xenial/universe amd64 libmcrypt-dev amd64 2.5.8-3.3 [83.7 kB]
Fetched 83.7 kB in 0s (105 kB/s)
Selecting previously unselected package libmcrypt-dev.
(Reading database ... 215484 files and directories currently installed.)
Preparing to unpack .../libmcrypt-dev_2.5.8-3.3_amd64.deb ...
Unpacking libmcrypt-dev (2.5.8-3.3) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up libmcrypt-dev (2.5.8-3.3) ...
YYY@YYY:/var/www/html/orocrm$ sudo pecl7.2-sp install --nodeps mcrypt-snapshot
sudo: pecl7.2-sp: command not found
因为我没有找到这种类型的错误pecl7.2-sp：command
从文档部分可以清楚地看出它已被弃用，从安全的角度来看不再可用 - 从那时起，从PHP 7.2.X的发布版本开始。
但是一些项目需要这些依赖项，以便在必要时执行所需的功能。我如何解决上述问题？
TL; DR：
我从投票到答案的答案得到了很多回应。需要根据OS体系结构级别对答案进行分类。由于我使用共享服务器进行托管，因此有多个项目驻留在它上面并且使用PHP 5.XX版本进行编码，所以我决定降级到默认情况下支持mcrypt扩展的PHP 7.1.X我的基于Debian的操作系统。
正如我已经在Installing mcrypt Extension on PHP 7.2的链接中提到的，由Server Pilot社区提供。这些人已经告诉更新版本的pecl-7.2可以在PHP-7.2上安装mcrypt。不幸的是，它以pecl7.2-sp: command not found从已执行的命令结束。后来网站页面得到了更新，因此那里的命令与执行时尝试的命令不匹配。
最后，无论哪种解决方案适合您的操作系统架构级别，只需去吧！
要么
如果以下方法没有产生解决根本原因。 或者，您可以使用默认支持mcrypt扩展的PHP 7.1.X版本
我按照以下步骤使用PECL为PHP7.2安装mcrypt。
apt-get install php-pecl
apt-get install libmcrypt-dev libreadline-dev
pecl install mcrypt-1.0.1
你应该在php.ini中添加“extension = mcrypt.so”
如果您需要任何帮助，请在下面评论。 :-)
Mcrypt PECL扩展
sudo apt-get -y install gcc make autoconf libc-dev pkg-config
sudo apt-get -y install libmcrypt-dev
sudo pecl install mcrypt-1.0.1
当您显示提示时
libmcrypt prefix? [autodetect] :
按[Enter]进行自动检测。
在成功安装mcrypt trought pecl之后，你应该将mcrypt.so扩展添加到php.ini。
输出将如下所示：
...
Build process completed successfully
Installing '/usr/lib/php/20170718/mcrypt.so' ----> this is our path to mcrypt extension lib
install ok: channel://pecl.php.net/mcrypt-1.0.1
configuration option "php_ini" is not set to php.ini location
You should add "extension=mcrypt.so" to php.ini
抓住安装路径并添加到cli和apache2 php.ini配置。
sudo bash -c "echo extension=/usr/lib/php/20170718/mcrypt.so > /etc/php/7.2/cli/conf.d/mcrypt.ini"
sudo bash -c "echo extension=/usr/lib/php/20170718/mcrypt.so > /etc/php/7.2/apache2/conf.d/mcrypt.ini"
验证是否已安装扩展
运行命令：
php -i | grep "mcrypt"
输出将如下所示：
/etc/php/7.2/cli/conf.d/mcrypt.ini
Registered Stream Filters => zlib.*, string.rot13, string.toupper, string.tolower, string.strip_tags, convert.*, consumed, dechunk, convert.iconv.*, mcrypt.*, mdecrypt.*
mcrypt
mcrypt support => enabled
mcrypt_filter support => enabled
mcrypt.algorithms_dir => no value => no value
mcrypt.modes_dir => no value => no value
@ praneeth-nidarshan主要涵盖了所有步骤，除了一些：
$ sudo apt-get install php-pear
sh：phpize：找不到
错误：`phpize'失败了
$ sudo apt-get install php7.2-dev
$ sudo pecl install mcrypt-1.0.1
extension=mcrypt.so
$ sudo php -i | grep 'Configuration File'x是你的php版本，如7.2的php7.2-dev
sudo apt-get install php-pear php7.x-dev
然后在“/etc/php/7.2/apache2/php.ini”中添加“extension = mcrypt.so”
这里的php.ini取决于你的php安装和apache使用php版本。
作为替代方案，您可以安装7.1版本的apt-get install libmcrypt-dev libreadline-dev
pecl install mcrypt-1.0.1
并创建一个符号链接：
安装php7.1-mcrypt：
mcrypt创建符号链接：
sudo apt install php7.1-mcrypt
在sudo ln -s /etc/php/7.1/mods-available/mcrypt.ini /etc/php/7.2/mods-available
启用mcrypt之后，它就可用了。