centos 7 升级后yum install出现Exiting on user cancel
centos 7.x升级后用yum install进行安装时经常出现Exiting on user cancel，例如：
[root@localhost ~]# yum install logstash
Loaded plugins: axelget, fastestmirror
No metadata available for base
No metadata available for docker-main-repo
No metadata available for epel
No metadata available for extras
No metadata available for logstash-1.5
No metadata available for updates
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* epel: mirrors.ustc.edu.cn
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com
Resolving Dependencies
--> Running transaction check
---> Package logstash.noarch 1:1.5.6-1 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=========================================================================================================================================================================================================
Package Arch Version Repository Size
=========================================================================================================================================================================================================
Installing:
logstash noarch 1:1.5.6-1 logstash-1.5 86 M
Transaction Summary
=========================================================================================================================================================================================================
Install 1 Package
Total download size: 86 M
Installed size: 133 M
Is this ok [y/d/N]: y
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
logstash-1.5.6-1.noarch.rpm | 0 B 00:00:30 ...
logstash-1.5.6-1.noarch.rpm 2% [== ] 141 kB/s | 2.5 MB 00:10:09 ETA
Exiting on user cancel
总是出现Exiting on user cancel，导致不能正常安装。
这是yum的一个bug导致的问题。修改/usr/lib/python2.7/site-packages/urlgrabber/grabber.py.
vi /usr/lib/python2.7/site-packages/urlgrabber/grabber.py
将第1510行和1517行注释掉即可
修改前：
1510 elif errcode == 42:
1511 # this is probably wrong but ultimately this is what happens
1512 # we have a legit http code and a pycurl 'writer failed' code
1513 # which almost always means something aborted it from outside
1514 # since we cannot know what it is -I'm banking on it being
1515 # a ctrl-c. XXXX - if there's a way of going back two raises to
1516 # figure out what aborted the pycurl process FIXME
1517 raise KeyboardInterrupt
修改后：
1510 #elif errcode == 42:
1511 # this is probably wrong but ultimately this is what happens
1512 # we have a legit http code and a pycurl 'writer failed' code
1513 # which almost always means something aborted it from outside
1514 # since we cannot know what it is -I'm banking on it being
1515 # a ctrl-c. XXXX - if there's a way of going back two raises to
1516 # figure out what aborted the pycurl process FIXME
1517 # raise KeyboardInterrupt
然后以root用户运行如下命令升级：
yum clean metadata
yum clean all
yum upgrade
升级完成后运行yum命令安装即可。
- 参考文档：
http://www.ostechnix.com/yum-dont-work-in-clean-centos-7-how-to-fix-it/