centos6.8 tree安装报错,安装nc报错

• gcc -ggdb -Wall -DLINUX -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -c -o tree.o tree.c
  make: gcc：命令未找到
  make: *** [tree.o] 错误 127
• 仓库 “CentOS-6 - Base - mirrors.aliyun.com” 的 GPG 密钥已安装，但是不适用于此软件包。请检查仓库的公钥 URL 是否配置正确。
• –bash: tree: command not found
• http://mirrors.aliyun.com/centos/6/updates/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - “The requested URL returned error: 404 Not Found”

• vim /etc/yum.repos.d/CentOS-Base.repo 删除原来的文件，将以下配置复制进来

# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the 
# remarked out baseurl= line instead.
#
#

[base]
name=CentOS-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
baseurl=https://vault.centos.org/6.8/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#released updates 
[updates]
name=CentOS-$releasever - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
baseurl=https://vault.centos.org/6.8/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
baseurl=https://vault.centos.org/6.8/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
baseurl=https://vault.centos.org/6.8/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib&infra=$infra
baseurl=https://vault.centos.org/6.8/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

• yum -y install tree
• tree ./
•