我无法安装 php-mbstring，命令结果如下：
# apt install php-mbstring
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
php-mbstring : Depends: php7.0-mbstring but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
系统信息：
# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"
安装的PHP包：
# dpkg -l |grep php
ii libapache2-mod-php 1:7.0+35ubuntu6 all server-side, HTML-embedded scripting language (Apache 2 module) (default)
ii libapache2-mod-php7.0 7.0.8-0ubuntu0.16.04.3 amd64 server-side, HTML-embedded scripting language (Apache 2 module)
ii php 1:7.0+35ubuntu6 all server-side, HTML-embedded scripting language (default)
ii php-cli-prompt 1.0.1+dfsg-1build1 all tiny helper prompting for user input
ii php-common 1:35ubuntu6 all Common files for PHP packages
ii php-composer-semver 1.2.0-1build1 all Semver library that offers utilities, version constraint parsing and
ii php-composer-spdx-licenses 1.1.2-1build1 all SPDX licenses list and validation library
ii php-curl 1:7.0+35ubuntu6 all CURL module for PHP [default]
ii php-gettext 1.0.11-2build1 all read gettext MO files directly, without requiring anything other than PHP
ii php-json-schema 1.6.1-1build1 all implementation of JSON schema
ii php-mysql 1:7.0+35ubuntu6 all MySQL module for PHP [default]
ii php-pear 1:1.10.1+submodules+notgz-6 all PEAR Base System
ii php-phpseclib 2.0.1-1build1 all implementations of an arbitrary-precision integer arithmetic library
ii php-symfony-console 2.7.10-0ubuntu2 all run tasks from the command line
ii php-symfony-filesystem 2.7.10-0ubuntu2 all basic filesystem utilities
ii php-symfony-finder 2.7.10-0ubuntu2 all find files and directories
ii php-symfony-process 2.7.10-0ubuntu2 all execute commands in sub-processes
ii php-xml 1:7.0+35ubuntu6 all DOM, SimpleXML, WDDX, XML, and XSL module for PHP [default]
ii php7.0 7.0.8-0ubuntu0.16.04.3 all server-side, HTML-embedded scripting language (metapackage)
ii php7.0-cli 7.0.8-0ubuntu0.16.04.3 amd64 command-line interpreter for the PHP scripting language
ii php7.0-common 7.0.8-0ubuntu0.16.04.3 amd64 documentation, examples and common module for PHP
ii php7.0-curl 7.0.8-0ubuntu0.16.04.3 amd64 CURL module for PHP
ii php7.0-json 7.0.8-0ubuntu0.16.04.3 amd64 JSON module for PHP
ii php7.0-mysql 7.0.8-0ubuntu0.16.04.3 amd64 MySQL module for PHP
ii php7.0-opcache 7.0.8-0ubuntu0.16.04.3 amd64 Zend OpCache module for PHP
ii php7.0-readline 7.0.8-0ubuntu0.16.04.3 amd64 readline module for PHP
ii php7.0-xml 7.0.8-0ubuntu0.16.04.3 amd64 DOM, SimpleXML, WDDX, XML, and XSL module for PHP
ii phpmyadmin 4:4.5.4.1-2ubuntu1 all MySQL web administration tool
所有来源都是最新的和升级的：
# apt update
Get:1 https://mirrors.gandi.net/ubuntu xenial-backports InRelease [92.2 kB]
Hit:1 https://mirrors.gandi.net/ubuntu xenial-backports InRelease
Ign:2 https://mirrors.gandi.net/gandi/ubuntu xenial InRelease
Hit:3 https://mirrors.gandi.net/ubuntu xenial-proposed InRelease
Hit:4 https://mirrors.gandi.net/ubuntu xenial-security InRelease
Hit:5 https://mirrors.gandi.net/ubuntu xenial-updates InRelease
Get:6 https://mirrors.gandi.net/ubuntu xenial InRelease [247 kB]
Hit:6 https://mirrors.gandi.net/ubuntu xenial InRelease
Hit:7 https://mirrors.gandi.net/gandi/ubuntu xenial Release
Get:8 https://mirrors.gandi.net/gandi/ubuntu xenial Release.gpg [198 B]
Fetched 198 B in 1s (161 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
W: https://mirrors.gandi.net/gandi/ubuntu/dists/xenial/Release.gpg: Signature by key 52596D104900956B55AA8A0ED8EAC2F4DAFE3FA5 uses weak digest algorithm (SHA1)
# apt dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
我不知道该如何处理，谢谢你的支持。David
我曾尝试使用官方的 ubuntu 镜像，但没有成功：
# apt update
Hit:1 http://fr.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit:2 http://security.ubuntu.com/ubuntu xenial-security InRelease
Hit:3 http://fr.archive.ubuntu.com/ubuntu xenial InRelease
Hit:4 http://fr.archive.ubuntu.com/ubuntu xenial-proposed InRelease
Hit:5 http://fr.archive.ubuntu.com/ubuntu xenial-updates InRelease
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
# apt install libapache2-mod-php7.0 phpmyadmin php7.0-mbstring
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
php7.0-mbstring : Depends: php7.0-common (= 7.0.4-7ubuntu2) but 7.0.8-0ubuntu0.16.04.3 is to be installed
E: Unable to correct problems, you have held broken packages.
我不知道该如何处理它...:(
有什么想法吗？谢谢帮助。
大卫
答案1
我找到的解决方案：在 xenial-updates 上添加了“universe”
# cat /etc/apt/sources.list.d/*
deb [arch=amd64] http://fr.archive.ubuntu.com/ubuntu/ xenial-backports main
deb [arch=amd64] http://fr.archive.ubuntu.com/ubuntu/ xenial main universe
deb [arch=amd64] http://fr.archive.ubuntu.com/ubuntu/ xenial-proposed main
deb [arch=amd64] http://security.ubuntu.com/ubuntu xenial-security main
deb [arch=amd64] http://fr.archive.ubuntu.com/ubuntu/ xenial-updates main universe