大意删除yum，提示-bash: /usr/bin/yum: No such file or directory
解决办法如下：

rpm -ivh --nodeps http://mirrors.163.com/centos/7.5.1804/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
rpm -ivh --nodeps http://mirrors.163.com/centos/7.5.1804/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-45.el7.noarch.rpm
rpm -ivh --nodeps http://mirrors.163.com/centos/7.5.1804/os/x86_64/Packages/yum-3.4.3-158.el7.centos.noarch.rpm

来自  https://blog.csdn.net/h330531987/article/details/80609573

linux输入yum后提示： -bash: /usr/bin/yum: No such file or directory的解决方案 
今天在安装程序时，发现有一个插件未安装，我就随手敲了一个命令,看都没看

yum remove yum

然后就杯具了…

[root@localhost ~]# yum 
-bash: /usr/bin/yum: No such file or directory 

这个粗心的手误倒不至于让整个系统瘫痪，yum 却无法使用了。于是，我试着折腾了一番

rpm -ivh  --nodeps http://mirrors.163.com/centos/5/os/x86_64/CentOS/yum-fastestmirror-1.1.16-14.el5.centos.1.noarch.rpm  
rpm -ivh  --nodeps http://mirrors.163.com/centos/5/os/x86_64/CentOS/yum-metadata-parser-1.1.2-3.el5.centos.x86_64.rpm  
rpm -ivh  --nodeps http://mirrors.163.com/centos/5/os/x86_64/CentOS/yum-3.2.22-26.el5.centos.noarch.rpm

关于rpm –nodeps的解释

--nodeps                         don't verify package dependencies 

接下来，再次尝试输入yum,结果再次出现莫名错误

[root@localhost ~]# yum 
 There was a problem importing one of the Python modules 
 required to run yum. The error leading to this problem was: 

 libxml2.so.2: cannot open shared object file: No such file or directory 

 Please install a package which provides this module, or 
 verify that the module is installed correctly. 

 It's possible that the above module doesn't match the 
 current version of Python, which is: 
 2.4.3 (#1, Nov 11 2010, 13:30:19)  
 [GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] 

 If you cannot solve this problem yourself, please go to  
 the yum faq at: 
 http://wiki.linux.duke.edu/YumFaq

因为yum调用的是python,运行 Python，试下是否可行

[root@localhost~]# python 
 Python 2.4.3 (#1, Nov 11 2010, 13:30:19)  
 [GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] on linux2 
 Type "help", "copyright", "credits" or "license" for more information. 
 >>> import yum 
 Traceback (most recent call last): 
   File "<stdin>", line 1, in ? 
   File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 54, in ? 
     import transactioninfo 
   File "/usr/lib/python2.4/site-packages/yum/transactioninfo.py", line 31, in ? 
     from sqlitesack import YumAvailablePackageSqlite 
   File "/usr/lib/python2.4/site-packages/yum/sqlitesack.py", line 26, in ? 
     import yumRepo 
   File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 32, in ? 
     import sqlitecachec 
   File "/usr/lib64/python2.4/site-packages/sqlitecachec.py", line 19, in ? 
     import _sqlitecache 
 ImportError: libxml2.so.2: cannot open shared object file: No such file or directory 
 >>>

提示缺少libxml2.so.2，安装一下试试

rpm -ivh http://mirrors.163.com/centos/5/os/x86_64/CentOS/libxml2-2.6.26-2.1.2.8.x86_64.rpm```

再次测试运行下yum命令，结果正常了，大喜

[root@localhost ~]# yum 
Loaded plugins: fastestmirror 
You need to give some command 
usage: yum [options] COMMAND

List of Commands:

check-update Check for available package updates 
clean Remove cached data 
deplist List a package’s dependencies 
downgrade downgrade a package 
erase Remove a package or packages from your system 
groupinfo Display details about a package group 
groupinstall Install the packages in a group on your system 
grouplist List available package groups 
groupremove Remove the packages in a group from your system 
help Display a helpful usage message 
info Display details about a package or group of packages 
install Install a package or packages on your system 
list List a package or groups of packages 
localinstall Install a local RPM 
makecache Generate the metadata cache 
provides Find what package provides the given value 
reinstall reinstall a package 
repolist Display the configured software repositories 
resolvedep Determine which package provides the given dependency 
search Search package details for the given string 
shell Run an interactive yum shell 
update Update a package or packages on your system 
upgrade Update packages taking obsoletes into account

options: 
-h, –help show this help message and exit 
-t, –tolerant be tolerant of errors 
-C run entirely from cache, don’t update cache 
-c [config file] config file location 
-R [minutes] maximum command wait time 
-d [debug level] debugging output level 
–showduplicates show duplicates, in repos, in list/search commands 
-e [error level] error output level 
-q, –quiet quiet operation 
-v, –verbose verbose operation 
-y answer yes for all questions 
–version show Yum version and exit 
–installroot=[path] set install root 
–enablerepo=[repo] enable one or more repositories (wildcards allowed) 
–disablerepo=[repo] disable one or more repositories (wildcards allowed) 
-x [package], –exclude=[package] 
exclude package(s) by name or glob 
–disableexcludes=[repo] 
disable exclude from main, for a repo or for 
everything 
–obsoletes enable obsoletes processing during updates 
–noplugins disable Yum plugins 
–nogpgcheck disable gpg signature checking 
–disableplugin=[plugin] 
disable plugins by name 
–enableplugin=[plugin] 
enable plugins by name 
–skip-broken skip packages with depsolving problems 
–color=COLOR control whether color is used

Plugin Options:

最后，赶紧更新一下系统吧

yum update 
“` 
好了 这样yum问题就完全解决了！

来自  https://blog.csdn.net/u012038649/article/details/68950785