小编wal*_*tor的帖子

如果我diff -q在两个文件上运行并且它们是相同的，则生成的退出代码echo $?是0; 如果文件不同，则退出代码为1. 这是为什么？第diff一个成功而第二个失败的方式是什么？

根据我对http://mywiki.wooledge.org/BashGuide/TestsAndConditionals 的阅读和有限的理解，我使用了“成功”和“失败”这两个术语：

1. 退出状态
   每个命令在终止时都会产生一个退出代码。
   任何启动它的应用程序都使用此退出代码来评估
   是否一切正常。此退出代码类似于
   函数的返回值。它是一个介于 0 到 255（含）之间的整数。约定
   规定我们使用 0 表示成功，使用任何其他数字表示
   某种类型的失败。具体数字完全是特定于应用程序的，
   用于提示究竟出了什么问题。

我应该man diff把开发人员使用的约定清楚地读到最后。

每隔几天我就会收到这些锁定服务器的错误。

[501.882940] print_req_error: I/O error, dev fd0, sector 0

[504.338961] print_req_error: I/O error, dev fd0, sector 0

[504.738984] print_req_error: I/O error, dev fd0, sector 0

[509.250929] print_req_error: I/O error, dev fd0, sector 0

[509.898921] print_req_error: I/O error, dev fd0, sector 0

[510.334916] print_req_error: I/O error, dev fd0, sector 0

[517.714867] print_req_error: I/O error, dev fd0, sector 0

[520.118801] print_req_error: I/O error, dev fd0, sector 0

[520.618864] print_req_error: I/O error, dev fd0, sector 0

[521.047029] print_req_error: I/O error, dev fd0, sector …

我注意到，当我拔掉笔记本电脑的插头，或合上/打开盖子时，我的无线连接每次都会掉线。

我将其追踪到pm-powersave，并使其停止，见下文。

这也可能导致重复请求网络密码。

我使用 Ubuntu 16.04 LTS 。HPLIP 3.16.3 附带了这个。我购买了一台新打印机 LaserJet Pro MFP M130nw，它至少需要 HPLIP 3.16.11。

我从 HP Developer 网站下载了自动安装程序（.run 文件）Download HPLIP 3.20.5。然后运行自动安装程序。

该过程进展顺利，直到 HP-PLUGIN 失败 - 请参阅下面的日志

HP Linux Imaging and Printing System (ver. 3.20.5)\nPlugin Installer ver. 3.0\nCopyright (c) 2001-18 HP Development Company, LP\nThis software comes with ABSOLUTELY NO WARRANTY.\nThis is free software, and you are welcome to distribute it\nunder certain conditions. See COPYING file for more details.\nPlug-in version: 3.20.5\nInstalled HPLIP version: 3.20.5\nNumber of files to install: 64\nPlugin installation …

Hit:1 http://si.archive.ubuntu.com/ubuntu artful InRelease
Hit:2 http:// si.archive.ubuntu.com/ubuntu artful-updates InRelease             
Hit:3 http:// si.archive.ubuntu.com/ubuntu artful-backports InRelease           
Hit:4 http:// download.virtualbox.org/virtualbox/debian xenial InRelease        
Err:3 http:// si.archive.ubuntu.com/ubuntu artful-backports InRelease           
  Splitting up /var/lib/apt/lists/si.archive.ubuntu.com_ubuntu_dists_artful-backports_InRelease into data and signature failed
Hit:5 https:// updates.signal.org/desktop/apt xenial InRelease           
Get:6 http:// security.ubuntu.com/ubuntu artful-security InRelease [78,6 kB]
Hit:7 http:// security.ubuntu.com/ubuntu artful-security/main amd64 Packages
Ign:7 http:// security.ubuntu.com/ubuntu artful-security/main amd64 Packages
Hit:8 http:// security.ubuntu.com/ubuntu artful-security/main i386 Packages
Hit:9 http:// security.ubuntu.com/ubuntu artful-security/main Translation-en
Hit:10 http:// security.ubuntu.com/ubuntu artful-security/main amd64 DEP-11 Metadata
Hit:11 http:// security.ubuntu.com/ubuntu artful-security/main DEP-11 64x64 …

 http://ppa.launchpad.net/ubuntugis/ppa/ubuntu bionic Release           
  404  Not Found [IP: 91.189.95.83 80]
Reading package lists... Done                                                 
E: The repository 'http://ppa.launchpad.net/ubuntugis/ppa/ubuntu bionic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

硬盘驱动器表现出超级损坏。欢迎任何帮助...我们无法物理访问这台计算机。我们可以通过ssh远程解决这个问题。

$ fsck -p -f  
fsck from util-linux 2.31.1
/dev/mapper/ubuntu--vg-root: recovering journal
fsck.ext4: unable to set superblock flags on /dev/mapper/ubuntu--vg-root


/dev/mapper/ubuntu--vg-root: ********** WARNING: Filesystem still has errors **********


$ reboot

Failed to open /dev/initctl: No such device or address
Failed to talk to init daemon.


# Ubuntu 18.04.1 LTS (GNU/Linux 4.15.0-38-generic x86_64)

 1 Time(s): audit: type=1400 audit(1473854574.089:113): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/lib/cups/backend/cups-pdf" pid=31430 comm="apparmor_parser"

 1 Time(s): audit: type=1400 audit(1473854574.089:114): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=31430 comm="apparmor_parser"

 1 Time(s): audit: type=1400 audit(1473854574.089:115): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=31430 comm="apparmor_parser"

我应该担心吗？

我正在运行 Ubuntu 14.04.5 LTS（GNU/Linux 4.4.0-36-generic x86_64）

我试图traceroute用于我的网络项目。但是每当我尝试安装traceroute它时都会显示

Reading package lists... Done  
Building dependency tree         
Reading state information... Done  
You might want to run 'apt--fix-broken install' to correct these.  
The following packages have unmet dependencies:
code : Depends: libgconf-2-4 but it is not going to be installed  
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).

然后我点击了这个链接。但它再次没有成功安装并显示，

Reading package lists... Done 
Building dependency tree        
Reading state information... Done 
You might want to run 'apt --fix-broken install' …

sudo apt-get install kubuntu-restricted-extras

似乎运行良好

sudo /usr/share/doc/libdvdread4/install-css.sh

给出：

sudo: /usr/share/doc/libdvdread4/install-css.sh: command not found

已运行 sudo apt-get update 多次

怎么修？如何安装 libdvdread4？

michaeleric@michaeleric-Inspiron-1750:~$ sudo apt-get install libdvdread4  
[sudo] password for michaeleric:   
Reading package lists... Done  
Building dependency tree          
Reading state information... Done  
libdvdread4 is already the newest version (5.0.3-1).  
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.  
michaeleric@michaeleric-Inspiron-1750:~$ sudo /usr/share/doc/libdvdread4/install-css.sh  
sudo: /usr/share/doc/libdvdread4/install-css.sh: command not found  
michaeleric@michaeleric-Inspiron-1750:~$   

===========================================

sudo apt install libdvdcss2 libdvdread4 libdvdnav4 ubuntu-restricted-extras

似乎安装

michaeleric@michaeleric-Inspiron-1750:~$ sudo /usr/share/doc/libdvdread4/install-css.shsudo: …