“E: Package ‘php-mcrypt’ has no installation candidate”

如何解决 “E: Package ‘php-mcrypt’ has no installation candidate”

今天的教程将在Ubuntu 20.04/18.04上安装PHP MCrypt扩展。
PHP MCRYPT扩展是MCRYPT加密库的接口，它支持各种块算法，如DES，TripleDes，Blowfish(默认)，3路，更安全-SK64，更安全的SK128，Twofish，Tea，RC2和CBC中的GOSTB，OFB，CFB和ECB密码模式。

如果我们尝试使用APT安装Mcrypt，则会收到错误：

$sudo apt install php-mcrypt
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package php-mcrypt is not available, but is referred to by another package.
This Jan mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'php-mcrypt' has no installation candidate

MCrypt扩展将移至PECL存储库，并且不再与PHP 7.2.0的PHP捆绑在一起。
PECL是所有已知的PHP扩展的存储库，用户可以下载和主机开发的PHP扩展。

告诉操作系统以提取安装库中可用的最新包列表：

sudo apt update

在Ubuntu上安装开发工具：

sudo apt update
sudo apt install -y build-essential

确认制作和GCC：

$gcc --version
gcc (Ubuntu 9.3.0-10ubuntu2) 9.3.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$make --version
GNU Make 4.2.1
Built for x86_64-pc-linux-gnu
Copyright (C) 1988-2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

我们需要首先在Ubuntu 20.04 | 18.04上安装PHP，DEV和PEAR扩展。

sudo apt install php php-pear php-dev libmcrypt-dev

确认系统中可用的PECL命令。

$which pecl 
/usr/bin/pecl

PECL使用率：

$pecl help
Commands:
build                  Build an Extension From C Source
bundle                 Unpacks a Pecl Package
channel-add            Add a Channel
channel-alias          Specify an alias to a channel name
channel-delete         Remove a Channel From the List
channel-discover       Initialize a Channel from its server
channel-info           Retrieve Information on a Channel
channel-login          Connects and authenticates to remote channel server
channel-logout         Logs out from the remote channel server
channel-update         Update an Existing Channel
clear-cache            Clear Web Services Cache
config-create          Create a Default configuration file
config-get             Show One Setting
config-help            Show Information About Setting
config-set             Change Setting
config-show            Show All Settings
convert                Convert a package.xml 1.0 to package.xml 2.0 format
cvsdiff                Run a "cvs diff" for all files in a package
cvstag                 Set CVS Release Tag
download               Download Package
download-all           Downloads each available package from the default channel
info                   Display information about a package
install                Install Package
list                   List Installed Packages In The Default Channel
list-all               List All Packages
list-channels          List Available Channels
list-files             List Files In Installed Package
list-upgrades          List Available Upgrades
login                  Connects and authenticates to remote server [Deprecated in favor of channel-login]
logout                 Logs out from the remote server [Deprecated in favor of channel-logout]
makerpm                Builds an RPM spec file from a PEAR package
package                Build Package
package-dependencies   Show package dependencies
package-validate       Validate Package Consistency
pickle                 Build PECL Package
remote-info            Information About Remote Packages
remote-list            List Remote Packages
run-scripts            Run Post-Install Scripts bundled with a package
run-tests              Run Regression Tests
search                 Search remote package database
shell-test             Shell Script Test
sign                   Sign a package distribution file
svntag                 Set SVN Release Tag
uninstall              Un-install Package
update-channels        Update the Channel List
upgrade                Upgrade Package
upgrade-all            Upgrade All Packages [Deprecated in favor of calling upgrade with no parameters]
Usage: pecl [options] command [command-options] <parameters>
Type "pecl help options" to list all options.
Type "pecl help shortcuts" to list all command shortcuts.
Type "pecl help version" or "pecl version" to list version information.
Type "pecl help <command>" to get the help for the specified command.

更新频道：

$sudo pecl channel-update pecl.php.net
Updating channel "pecl.php.net"
Update of Channel "pecl.php.net" succeeded
$sudo pecl update-channels
Updating channel "doc.php.net"
Update of Channel "doc.php.net" succeeded
Updating channel "pear.php.net"
Update of Channel "pear.php.net" succeeded
Updating channel "pecl.php.net"
Channel "pecl.php.net" is up to date

让我们搜索mcrypt扩展。

$sudo pecl search mcrypt
Matched packages, channel pecl.php.net:
=======================================
Package       Stable/(Latest) Local
mcrypt        1.0.3 (stable)        Bindings for the libmcrypt library
mcrypt_filter 0.1.0 (beta)          Applies mcrypt symmetric encryption using stream filters

我们可以使用PECL命令安装Mcrypt扩展名，使用"安装"选项。

$sudo pecl install mcrypt
downloading mcrypt-1.0.3.tgz ...
Starting to download mcrypt-1.0.3.tgz (33,590 bytes)
.........done: 33,590 bytes
6 source files, building
running: phpize
Configuring for:
PHP Api Version:         20190902
Zend Module Api No:      20190902
Zend Extension Api No:   320190902
........

当你看到提示时

libmcrypt prefix? [autodetect] :

按Enter键自动检测。

我们应该在ubuntu 20.04 Linux机器上完成下面的输出，如下面完成Mcrypt扩展的安装。

Build process completed successfully
Installing '/usr/lib/php/20190902/mcrypt.so'
install ok: channel://pecl.php.net/mcrypt-1.0.3
configuration option "php_ini" is not set to php.ini location
You should add "extension=mcrypt.so" to php.ini

在php.ini文件中启用扩展名。

Ubuntu 20.04：

$sudo vim /etc/php/7.4/cli/php.ini
extension=mcrypt.so
$sudo vim /etc/php/7.4/apache2/php.ini
extension=mcrypt.so

Ubuntu 18.04：

$sudo vim /etc/php/7.2/cli/php.ini
extension=mcrypt.so
$sudo vim /etc/php/7.2/apache2/php.ini
extension=mcrypt.so

我们可以确认使用命令已安装并启用该模块：

$php -m | grep mcrypt
mcrypt

如果使用带有Apache或者Nginx Web服务器托管的应用程序重新启动它们。

--- Restart Apache web server --
$sudo systemctl restart apache2
--- Restart nginx web server --
$sudo systemctl restart nginx