資訊專欄INFORMATION COLUMN
摘要：起因之前在網上看文章提到說，通過的方式安裝，可能安裝不是最新版本的情況，考慮到在下第一次安裝，以后肯定會有卸載重新安裝新版本的需求，剛好剛開始學習，索性練習下卸載重裝的過程。
起因
之前在網上看文章提到說，通過apt-get的方式安裝nginx，可能安裝不是最新版本的情況，考慮到在Ubuntu下第一次安裝nginx，以后肯定會有卸載重新安裝新版本的需求，剛好剛開始學習nginx，索性練習下卸載重裝的過程。
使用Ubuntu下的包管理工具apt來安裝nginx
$ sudo apt-get install nginx卸載
同樣使用apt來卸載nginx
$ sudo apt-get remove nginx
sudo apt-get autoremove命令幫我們卸載不再需要的依賴包
在這里我們卸載nginx相關的依賴包
$ sudo apt-get autoremove
刪除nginx配置文件夾
$ sudo rm -rf /etc/nginx重新安裝nginx
# 更新源 $ sudo apt update $ sudo apt-get install nginx
然而控制臺報錯：
Job for nginx.service failed because the control process exited with error code. See "systemctl status nginx.service" and "journalctl -xe" for details. invoke-rc.d: initscript nginx, action "start" failed. dpkg: error processing package nginx-core (--configure): subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of nginx: nginx depends on nginx-core (>= 1.10.3-0ubuntu0.16.04.2) | nginx-full (>= 1.10.3-0ubuntu0.16.04.2) | nginx-light (>= 1.10.3-0ubuntu0.16.04.2) | nginx-extras (>= 1.10.3-0ubuntu0.16.04.2); however: Package nginx-core is not configured yet. Package nginx-full is not installed. Package nginx-light is not installed. Package nginx-extras is not installed. nginx depends on nginx-core (<< 1.10.3-0ubuntu0.16.04.2.1~) | nginx-full (<< 1.10.3-0ubuntu0.16.04.2.1~) | nginx-light (<< 1.10.3-0ubuntu0.16.04.2.1~) | nginx-extras (<< 1.10.3-0ubuntu0.16.04.2.1~); however: Package nginx-core is not configured yet. No apport report written because the error message indicates its a followup error from a previous failure. Package nginx-full is not installed. Package nginx-light is not installed. Package nginx-extras is not installed. dpkg: error processing package nginx (--configure): dependency problems - leaving unconfigured Processing triggers for libc-bin (2.23-0ubuntu9) ... Errors were encountered while processing: nginx-core nginx E: Sub-process /usr/bin/dpkg returned an error code (1)
查看nginx.service狀態
$ systemctl status nginx.service
● nginx.service - A high performance web server and a reverse proxy server Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Sat 2018-03-17 23:16:40 CST; 1min 18s ago Process: 26795 ExecStartPre=/usr/sbin/nginx -t -q -g daemon on; master_process on; (code=exited, status=1/FAILURE) Main PID: 18259 (code=exited, status=0/SUCCESS) Mar 17 23:16:40 VM-0-5-ubuntu systemd[1]: Starting A high performance web server and a reverse proxy server... Mar 17 23:16:40 VM-0-5-ubuntu nginx[26795]: nginx: [emerg] open() "/etc/nginx/nginx.conf" failed (2: No such file or direMar 17 23:16:40 VM-0-5-ubuntu nginx[26795]: nginx: configuration file /etc/nginx/nginx.conf test failed Mar 17 23:16:40 VM-0-5-ubuntu systemd[1]: nginx.service: Control process exited, code=exited status=1 Mar 17 23:16:40 VM-0-5-ubuntu systemd[1]: Failed to start A high performance web server and a reverse proxy server. Mar 17 23:16:40 VM-0-5-ubuntu systemd[1]: nginx.service: Unit entered failed state. Mar 17 23:16:40 VM-0-5-ubuntu systemd[1]: nginx.service: Failed with result "exit-code".
仔細看報錯信息，獲取到兩個信息點：
Package nginx-core is not configured yet.
Package nginx-full/nginx-light/nginx-extras is not installed.
于是上網搜，網上找說可能是apache占用了80端口導致報錯
查看端口占用情況
$ sudo netstat -nlp
Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1287/sshd udp 0 0 0.0.0.0:68 0.0.0.0:* 891/dhclient udp 0 0 172.21.0.5:123 0.0.0.0:* 1231/ntpd udp 0 0 127.0.0.1:123 0.0.0.0:* 1231/ntpd udp 0 0 0.0.0.0:123 0.0.0.0:* 1231/ntpd udp6 0 0 :::123 :::* 1231/ntpd
發現80端口沒被占用，而且systemctl status nginx.service的提示信息也沒提及80端口被占用，如果提示信息中說80端口被占用，可以執行以下兩步試試：
終止apache運行
$ sudo service apache2 stop
重新安裝nginx
$ sudo apt-get install nginx
了解詳細信息請看askubuntu上的提問
上述情況與我的并不相符，于是換個思路，報錯信息中提及nginx的配置文件不存在，思考為什么卸載重裝nginx，卻沒有生成配置文件？
和第一次安裝的時候不一樣，然后百度上搜nginx卸載重裝后配置文件沒有重新生成，找到了類似的問題，給出了如下的操縱步驟：
卸載nginx不保留配置文件
$ sudo apt-get --purge remove nginx Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: fontconfig-config fonts-dejavu-core libfontconfig1 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libtiff5 libvpx3 libxpm4 libxslt1.1 nginx-common nginx-core Use "sudo apt autoremove" to remove them. The following packages will be REMOVED: nginx* 0 upgraded, 0 newly installed, 1 to remove and 205 not upgraded. 2 not fully installed or removed. After this operation, 37.9 kB disk space will be freed. Do you want to continue? [Y/n] y (Reading database ... 66386 files and directories currently installed.) Removing nginx (1.10.3-0ubuntu0.16.04.2) ... Setting up nginx-core (1.10.3-0ubuntu0.16.04.2) ... Job for nginx.service failed because the control process exited with error code. See "systemctl status nginx.service" and "journalctl -xe" for details. invoke-rc.d: initscript nginx, action "start" failed. dpkg: error processing package nginx-core (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: nginx-core E: Sub-process /usr/bin/dpkg returned an error code (1)
卸載自動安裝且不再需要的依賴包
$ sudo apt-get autoremove Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be REMOVED: fontconfig-config fonts-dejavu-core libfontconfig1 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libtiff5 libvpx3 libxpm4 libxslt1.1 nginx-common nginx-core 0 upgraded, 0 newly installed, 13 to remove and 205 not upgraded. 1 not fully installed or removed. After this operation, 9,745 kB disk space will be freed. Do you want to continue? [Y/n] y (Reading database ... 66383 files and directories currently installed.) Removing nginx-core (1.10.3-0ubuntu0.16.04.2) ... Removing libgd3:amd64 (2.1.1-4ubuntu0.16.04.8) ... Removing libfontconfig1:amd64 (2.11.94-0ubuntu1.1) ... Removing fontconfig-config (2.11.94-0ubuntu1.1) ... Removing fonts-dejavu-core (2.35-1) ... Removing libtiff5:amd64 (4.0.6-1ubuntu0.2) ... Removing libjbig0:amd64 (2.1-3.1) ... Removing libjpeg8:amd64 (8c-2ubuntu8) ... Removing libjpeg-turbo8:amd64 (1.4.2-0ubuntu3) ... Removing libvpx3:amd64 (1.5.0-2ubuntu1) ... Removing libxpm4:amd64 (1:3.5.11-1ubuntu0.16.04.1) ... Removing libxslt1.1:amd64 (1.1.28-2.1ubuntu0.1) ... Removing nginx-common (1.10.3-0ubuntu0.16.04.2) ... Processing triggers for libc-bin (2.23-0ubuntu9) ... Processing triggers for man-db (2.7.5-1) ...
篩選已安裝軟件包中與nginx有關的
$ dpkg --get-selections | grep nginx nginx-common deinstall
卸載nginx-common不保留配置文件
$ sudo apt-get --purge remove nginx-common Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be REMOVED: nginx-common* 0 upgraded, 0 newly installed, 1 to remove and 205 not upgraded. After this operation, 0 B of additional disk space will be used. Do you want to continue? [Y/n] y (Reading database ... 66243 files and directories currently installed.) Removing nginx-common (1.10.3-0ubuntu0.16.04.2) ... Purging configuration files for nginx-common (1.10.3-0ubuntu0.16.04.2) ... dpkg: warning: while removing nginx-common, directory "/var/www/html" not empty so not removed
重新安裝nginx
$ sudo apt-get install nginx ...
查看版本號，執行nginx配置文件語法檢測
$ nginx -v nginx version: nginx/1.10.3 (Ubuntu) $ sudo nginx -t nginx: the configuration file /etc/nginx/nginx.conf syntax is ok nginx: configuration file /etc/nginx/nginx.conf test is successful
apt-get autoremove到底是按什么規則卸載軟件？
為什么nginx-common沒有在一開始的時候卸載？
1. apt-get autoremove到底是按什么規則卸載軟件？apt-get autoremove：刪除，自動安裝的，且不再需要的
（不被其他軟件當作依賴的）軟件包
舉個栗子: 通過apt-get方式安裝nginx時，會通過引導自動安裝所需的依賴包（nginx-core），而當我們卸載nginx后，
那些自動安裝的依賴包就成為不再需要的軟件包（nginx-core），通過apt-get autoremove會自動清理它們
既然會自動刪除不再需要的軟件包，那么為什么nginx-common沒被刪除？
2. 為什么nginx-common沒有在apt-get autoremove的時候卸載？不知道細心的童鞋發現沒，我們在卸載nginx的時候，
手動刪除了nginx的配置文件夾（sudo rm -rf /etc/nginx）。
那這些配置文件夾和nginx-common軟件包有什么關系呢？
通過查找ubuntu packages，找到了Ubuntu16.0.4下nginx-common軟件包的文件清單。
按照清單上的目錄手動排查，發現本機上除了手動刪除的/etc/nginx目錄不存在，文件清單內的其他文件都沒有被刪除，猜測可能是nginx-common軟件包完整性被破壞，導致autoremove的時候沒有被刪除，當然這只我的猜測。
整理完全卸載nginx命令時，發現執行如下命令，ngnix的配置文件并沒有被刪除
$ sudo apt-get remove --purge nginx
查閱ubuntu packages發現，nginx依賴nginx-core，nginx-core依賴nginx-common，且其中nginx的配置文件屬于nginx-common軟件包配置文件的一部分。
執行如下命令進一步驗證
# 卸載nginx-common ，nginx配置文件不會被刪除 $ sudo apt-get remove nginx-common ... # 卸載nginx-common，nginx配置文件已經被刪除（包括但不限于） $ sudo apt-get remove --purge nginx-common $ find /etc/nginx/ find: ‘/etc/nginx/’: No such file or directory
apt-get autoremove執行時，nginx-common軟件包已經被選擇用于卸載( deinstall )，但是實際還沒有卸載。
$ dpkg --get-selections| grep nginx nginx-common deinstall
了解更多關于deinstall，點擊這里，如果有知道為什么的同學請不吝賜教。
# 完全卸載nginx $ sudo apt-get remove --purge nginx $ sudo apt-get autoremove --purge # 更新nginx，保留配置文件 # 親測nginx.conf不會被刪除和覆蓋，但保險起見還是建議先備份 $ sudo apt-get remove nginx $ sudo apt-get autoremove $ sudo apt update $ sudo apt-get install nginx # 安裝軟件包 # sudo apt-get install 軟件包名稱` # eg: $ sudo apt-get install nginx # 卸載軟件包 # sudo apt-get remove 軟件包名稱 # eg: $ sudo apt-get remove nginx # 卸載軟件包且不保留配置文件 # sudo apt-get remove --purge 軟件包名稱 # eg: $ sudo apt-get remove --purge nginx # 卸載自動安裝的軟件包且不保留配置文件 # sudo apt-get autoremove --purge # 列出本地軟件包列表 # dpkg --get-selections [| grep 篩選關鍵字] # eg:（列出本地所有軟件包） $ dpkg --get-selections # eg:（列出本地與ngnix有關的軟件包） $ dpkg --get-selections | grep nginx # 查看進程信息 # ps -ef [| grep 篩選關鍵字] # eg:（列出所有進程信息） $ ps -ef # eg:（列出與nginx有關的進程信息） $ ps -ef | grep nginx # 查看端口占用信息 $ sudo netstat -nlp
Package nginx-core not configured yet.Sub-process :/user/bin/dpkg returned an error code(1)nginx fail to install on Ubuntu 15.10 server
Ubuntu 14.04上卸載nginx之后重新安裝沒有重新生成配置文件的解決方法
在 xenial 發行版中 all 硬件架構下的 nginx-common 軟件包文件清單
What is difference between the options “autoclean”, “autoremove” and “clean”?
dpkg --get-selections shows packages marked “deinstall”
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