一. 文件和目录类

1. File exist 文件已经存在

[root@oldboyedu59 ~]# mkdir   /data   /lidao
[root@oldboyedu59 ~]# mkdir   /data   /lidao
mkdir: cannot create directory ‘/data’: File exists
mkdir: cannot create directory ‘/lidao’: File exists

mkdir: cannot create directory ‘/lidao’: File exists

无法   创建    目录   因为这个目录已经存在

2. No such file or directory 没有这个文件或目录(这个东西不存在)

没有这个目录:文件或路径书写错误

[root@oldboyedu59 ~]# mkdir  /oldboy
[root@oldboyedu59 ~]# cd oldboy
-bash: cd: oldboy: No such file or directory

mkdir命令本身问题:mkdir 命令默认只能创建1层目录 创建多层报错
-p解决

[root@oldboyedu59 ~]# mkdir  /data/oldboy/lidao/
mkdir: cannot create directory ‘/data/oldboy/lidao/’: No such file or directory

touch命令只能创建文件,目录不存在则会报错
解决:先创建目录,再创建文件

[root@oldboyedu59 ~]# ls /oldboy/oldboy.txt
[root@oldboyedu59 ~]# touch /oldboy/lidao/alex/oldboy.txt
touch: cannot touch ‘/oldboy/lidao/alex/oldboy.txt’: No such file or directory

排错思路:
1.ls命令检查对应的目录是否存在?
2.目录不存在 先创建目录在创建文件/

3. command not found 命令找不到(没有这个命令)

[root@oldboyedu59 ~]# mkdiy
-bash: mkdiy: command not found

1.书写错误
2.没有安装

4. invalid option   无效的参数(不可用的参数)

 [root@oldboyedu59 ~]# touch -p /oldboy/oldboy.txttouch: invalid option -- 'p'Try 'touch --help' for more information.

5. overwrite  覆盖

cp复制如果已经存在这个文件会提示是否覆盖

[root@oldboyedu59 ~]# cp  /oldboy/oldboy.txt   /tmp/
cp: overwrite ‘/tmp/oldboy.txt’?

6.remove regular empty file 是否删除普通文件(空的)?

[root@oldboyedu59 ~]# rm   /oldboy/oldboy.txt
rm: remove regular empty file ‘/oldboy/oldboy.txt’?

7. is a directory xxx是一个目录

rm默认无法删除目录
解决:加上-r 或-rf

[root@oldboyedu59 ~]# rm /data/
rm: cannot remove ‘/data/’: Is a directory

vi命令中 使用vi编辑目录也会报错

"/oldboy"E502: "/oldboy" is a directory
Press ENTER or type command to continue

8. descend into directory 是否进入目录

[root@oldboyedu59 ~]# rm -r /data/
rm: descend into directory ‘/data/’? y
rm: remove regular empty file ‘/data/oldboy01.txt’? n
rm: remove regular empty file ‘/data/oldboy02.txt’? n
rm: remove regular empty file ‘/data/oldboy03.txt’? n
rm: remove regular empty file ‘/data/oldboy04.txt’? n
rm: remove regular empty file ‘/data/oldboy05.txt’? n
rm: remove regular empty file ‘/data/oldboy06.txt’? n
rm: remove regular empty file ‘/data/oldboy07.txt’? n
rm: remove regular empty file ‘/data/oldboy08.txt’? n
rm: remove regular empty file ‘/data/oldboy09.txt’? n
rm: remove regular empty file ‘/data/oldboy10.txt’? n
rm: remove directory ‘/data/’? n

9. Invalid level 无效的层数,层数必须大于0

注意参数位置，数字需要加在-L后面

[root@oldboyedu59 ~]# tree  -L -F 2 /
tree: Invalid level, must be greater than 0.

10.   Can't open file for writing 无法打开这个文件

vi中 如果目录不存在就会提示

"/oldbyo/oldboy.txt"
"/oldbyo/oldboy.txt" E212: Can't open file for writing
Press ENTER or type command to continue

11.No write since last change

E37: No write since last change (add ! to override)粘包赖(你修改了内容就无法使用:q退出 需要使用:q!

12.  xx  column window is too narrow  窗口只有xx列太窄了 无法完全显示

这是w的坑 空间太小施展不开.

[root@oldboyedu60-lnb ~]# ww: 39 column window is too narrow

二. 网络连接类

1. 远程连接错误 Connection Failed 连接失败

使用Xshell远程连接失败提示,检查端口是否开启或正确

[c:\~]$ Connecting to 10.0.0.200:233...
Could not connect to '10.0.0.200' (port 233): Connection failed.Type `help' to learn how to use Xshell prompt.

使用telnet测试端口是否打开

[c:\~]$ telnet 10.0.0.200 233
Connecting to 10.0.0.200:233...
Could not connect to '10.0.0.200' (port 233): Connection failed.   #233端口没有开启
Type `help' to learn how to use Xshell prompt.

端口开启

[c:\~]$ telnet 10.0.0.200 22
Connecting to 10.0.0.200:22...
Connection established.            #端口开启To escape to local shell, press 'Ctrl+Alt+]'.
SSH-2.0-OpenSSH_7.4Protocol mismatch.Connection closed by foreign host.Disconnected from remote host(10.0.0.200:22) at 12:22:54.Type `help' to learn how to use Xshell prompt.
[c:\~]$

2. yum安装软件故障提示 Could not resolve host无法解析主机

Could not resolve host无法解析主机
主要是系统能否上网和DNS问题.

http://mirrors.tuna.tsinghua.edu.cn/centos/7.6.1810/updates/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "
Could not resolve host: mirrors.tuna.tsinghua.edu.cn; Unknown error"
Trying other mirror.

3.yum安装软件提示:Nothing to do (没事做)

有两种情况:
情况1:软件已经安装并且最新如下:

Package tree-1.6.0-10.el7.x86_64 already installed and latest version
tree软件包已经安装并且是最新版本
Package 2:vim-enhanced-7.4.160-5.el7.x86_64 already installed and latest version
Package 1:bash-completion-2.1-6.el7.noarch already installed and latest version
Nothing to do

情况2:软件名字写错或没有配置yum源导致找不到这个软件包

[root@oldboyedu60-lnb ~]# yum install treea -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile* base: mirror.lzu.edu.cn* extras: mirrors.nwsuaf.edu.cn* updates: mirrors.nwsuaf.edu.cn
base                                                                                              | 3.6 kB  00:00:00
extras                                                                                            | 3.4 kB  00:00:00     updates                                                                                           | 3.4 kB  00:00:00
No package treea available.
#没有找到叫treea的软件包
Error: Nothing to do

4. Name or service not known  域名无法识别(无法上网）

原因1：DNS配置错误
原因2：Linux无法上网原因 https://www.jianshu.com/p/0bc0b596c1a0

[root@oldboyedu59 ~]# ping baidu.com
ping: baidu.com: Name or service not known域名无法识别（无法将域名---->ip地址)

三. 修改系统基础配置类

1. 重启网卡报错 device not present

[root@oldboyusd ~]# systemctl restart network
Job for network.service failed because the control process exited with error code.See "systemctl status network.service" and "journalctl -xe" for details.

查看详细错误原因
·journalctl -xe·

Apr 01 15:31:05 oldboyusd.1 network[7816]: Bringing up interface etho:  ERROR     : [/etc/sysconfig/network-scripts/ifup-eth] Device  does not seem to be present, delaying initialization.Apr 01 15:31:05 oldboyusd.1 /etc/sysconfig/network-scripts/ifup-eth[8019]: Device  does not seem to be present, delaying initializatio

2.  修改主机名过程中,命令行中主机名没有变化

1# hostname命令修改主机名（临时 重启服务器之后失效）

[root@oldboyedu59 ~]# hostname
oldboyedu59
[root@oldboyedu59 ~]# hostname oldboyedu59-lnb

2# 修改文件内容（写合同    永久 重启服务器之后生效）

vim /etc/hostname oldboyedu59-lnb

3# 检查

[root@oldboyedu59 ~]# hostname
oldboyedu59-lnb
[root@oldboyedu59 ~]# cat /etc/hostname
oldboyedu59-lnb

命令行中的主机名部分没有改变？

解决：重新登录下即可（断开连接，重新连接）

[root@oldboyedu59-lnb ~]#