package 'aptitude' has no installation candidate

This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'libopts25' has no installation candidate …    面试必备知识点指针的深入解读,从此面对指针不再陌生 平均归一化滤波器组 这个是出自那篇论文, 自学零基础入门新版C语言视频教程是2020年2月录制,分为14章72集 方法2很好用,不知道为啥,方法1只有在设置了 `LC_ALL` 为 en_US.UTF-8 才有用, 不正经的kimol君:    玩转C语言文件操作之文件的打开关闭、删除、读写 I haven't changed my sources list after installing, could something in the sources cause this? any help. E: Package 'libssl1.0.0' has no installation candidate However there's a candidate to install the libssl-dev package, but none for the libssl1.0.0 I'm new with docker; does the perl 5.22 base image already come with libssl1.0.0 already preinstalled in the image? 妙&h, 大学生网页设计大作业-以下5个网页设计制作作品自己任选: 1.网页制作基础大二dw作业 2.w. 方法2很好用,不知道为啥,方法1只有在设置了 `LC_ALL` 为 en_US.UTF-8 才有用, https://blog.csdn.net/TH_NUM/article/details/103966244, python 报错Microsoft Visual C++ 14.0 is required, pip安装报错:is not a supported wheel on this platform, Python3中遇到UnicodeEncodeError: 'ascii' codec can't encode characters in ordinal not in range(128). 【综合项目实战-学生管理系统】 Package aptitude is not available, but is referred to by another package. 某个夜深人静的夜晚,夜微凉风微扬,月光照进我的书房~ 以上掌握技能之后,将会带你学习如何进行多表操作,关系的建立,各种连接查询等. So, we can easily find the ruby path using :- passenger - config -- ruby - command When we run then we will get like :-   Command: /home/rohit/.rvm/gems/ruby -2.1.10/wrappers/ruby   Version: ruby 2.1.10p492 (2016-04-01 revision 54464) [x86_64-linux]   To use in Apache : PassengerRuby /home/rohit/.rvm/gems/ruby -2.1.10/wrappers/ruby   To use in Nginx : passenger_ruby /home/rohit/.rvm/gems/ruby -2.1.10/wrappers/ruby   To use with Standalone: /home/rohit/.rvm/gems/ruby -2.1.10/wrappers/ruby /usr/bin/passenger start Add that line in passenger.conf file, WHEN WE ENTER , SHOW LINE NUMBER IN TEXT AREA HTML PAGE:- <%= text_area_tag :query_editor, '' :name => "query_editor", :class => "add_query_editor" %>