第八课
nice值
- 什么是nice值
给进程设置的优先级就是nice。nice的范围是-20~20。nice值越小占用的系统资源就越多，就是这个进程不nice。
- 如何查看nice值
# 使用top命令查看时 会有一列时NI 就是nice值
top - 14:01:36 up 9 min, 2 users, load average: 0.08, 0.23, 0.18
Tasks: 494 total, 2 running, 492 sleeping, 0 stopped, 0 zombie
%Cpu(s): 16.7 us, 16.7 sy, 0.0 ni, 66.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3742 root 20 0 619884 18616 12072 R 60.4 1.0 0:00.85 gnome-terminal-
3778 root 20 0 123924 1940 1152 R 60.4 0.1 0:00.43 top
1 root 20 0 53692 7660 2524 S 0.0 0.4 0:03.93 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.07 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:00.34 ksoftirqd/0
5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H
7 root rt 0 0 0 0 S 0.0 0.0 0:00.66 migration/0 - 设置nice值
# 执行4个 dd命令 一致在吃资源
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3985 root 20 0 107920 624 532 R 95.6 0.0 0:14.21 dd if=/dev/zero of=/dev/null
3977 root 20 0 107920 624 532 R 93.7 0.0 0:15.64 dd if=/dev/zero of=/dev/null
3981 root 20 0 107920 620 532 R 86.4 0.0 0:14.18 dd if=/dev/zero of=/dev/null
3973 root 20 0 107920 624 532 R 84.4 0.0 0:16.26 dd if=/dev/zero of=/dev/null
# renice 其那两个nice值为-20
renice -19 3977
renice -20 3985
renice +19 3981
renice +19 3973
#再次查看top
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3977 root 1 -19 107920 624 532 R 100.0 0.0 10:14.42 dd if=/dev/zero of=/dev/null
3985 root 0 -20 107920 624 532 R 100.0 0.0 10:38.96 dd if=/dev/zero of=/dev/null
3981 root 39 19 107920 620 532 R 96.5 0.0 10:01.17 dd if=/dev/zero of=/dev/null
3973 root 39 19 107920 624 532 R 88.6 0.0 9:55.61 dd if=/dev/zero of=/dev/null
# 修改后-20的进程一直比19nice值得占用的多，此时如果再开一个进程会更明显，但是虚拟机卡住了，做不了任何操作调整时间
- timedatectl
# 查看
[root@master /]# timedatectl
Local time: Fri 2019-08-30 14:21:58 CST
Universal time: Fri 2019-08-30 06:21:58 UTC
RTC time: Fri 2019-08-30 14:21:58
Timezone: Asia/Shanghai (CST, +0800)
NTP enabled: yes
NTP synchronized: no
RTC in local TZ: no
DST active: n/a
# 设置时间
[root@master /]# timedatectl set-time "2019-08-30 14:24:20"
[root@master /]# date
Fri Aug 30 14:24:23 CST 2019
# 查看所有时区
[root@master /]# timedatectl list-timezones
# 设置时区
[root@master /]# timedatectl set-timezone Asia/Hong_Kong
# 设置ntp同步为yes
timedatectl set-ntp 1- 自动对时
使用的时服务 chronyd。redhat7自带的。
# 编辑配置文件，注释掉默认的4行，增加阿里云的同步时间配置
[root@master ~]# vi /etc/chrony.conf
#server 0.rhel.pool.ntp.org iburst
#server 1.rhel.pool.ntp.org iburst
#server 2.rhel.pool.ntp.org iburst
#server 3.rhel.pool.ntp.org iburst
server ntp6.aliyun.com iburst
[root@localhost ~]# vi /etc/chrony.conf
[root@localhost ~]# vi /etc/chrony.conf
[root@localhost ~]# systemctl restart chronyd
[root@localhost ~]# systemctl enable chronyd
安装软件包
什么时RPM：RPM package manager 包管理
包的全名：
httpd-tools-2.4.6-17.el7.x86_64.rpm
# httpd-tools是名字
# 2.4.6是版本
# 17是发行班号（发行的次数）
# .el7是radhat7平台
# .x86_64处理器cpu的架构
# .noarch是32位64位都可以- 考试提供的iso镜像中有rpm的包。挂载后直接使用
[root@localhost /]# mount /dev/sr0 /mnt
mount: /dev/sr0 is write-protected, mounting read-only
[root@localhost /]# cd /mnt/Packages/
# packages下面全都是rpm包
# -i 安装 -v详细信息 -h 显示进度条
[root@localhost Packages]# rpm -ivh tree-1.6.0-10.el7.x86_64.rpm
warning: tree-1.6.0-10.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
Preparing... ################################# [100%]
Updating / installing...
1:tree-1.6.0-10.el7 ################################# [100%]
# 卸载
[root@localhost Packages]# rpm -evh tree
Preparing... ################################# [100%]
Cleaning up / removing...
1:tree-1.6.0-10.el7 ################################# [100%]
# 查看包
[root@localhost Packages]# rpm -q tree
tree-1.6.0-10.el7.x86_64
#查看所有包，太多了不直接显示
[root@localhost Packages]# rpm -qa|grep "tree"
tree-1.6.0-10.el7.x86_64
# 查看包的详细
[root@localhost Packages]# rpm -qi tree
Name : tree
Version : 1.6.0
Release : 10.el7
Architecture: x86_64
Install Date: Fri 30 Aug 2019 04:16:26 PM CST
Group : Applications/File
Size : 89505
License : GPLv2+
Signature : RSA/SHA256, Thu 03 Apr 2014 05:33:48 AM CST, Key ID 199e2f91fd431d51
Source RPM : tree-1.6.0-10.el7.src.rpm
Build Date : Tue 28 Jan 2014 01:29:58 AM CST
Build Host : x86-020.build.eng.bos.redhat.com
Relocations : (not relocatable)
Packager : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Vendor : Red Hat, Inc.
URL : http://mama.indstate.edu/users/ice/tree/
Summary : File system tree viewer
Description :
The tree utility recursively displays the contents of directories in a
tree-like format. Tree is basically a UNIX port of the DOS tree
utility.
# 查看包装在哪里
[root@localhost Packages]# rpm -ql tree
/usr/bin/tree
/usr/share/doc/tree-1.6.0
/usr/share/doc/tree-1.6.0/LICENSE
/usr/share/doc/tree-1.6.0/README
/usr/share/man/man1/tree.1.gz
# 查看文件从哪个包来的
[root@localhost Packages]# rpm -qf /usr/share/doc/tree-1.6.0
tree-1.6.0-10.el7.x86_64关于rpm 包的依赖问题
树形依赖:
a->b->c直接按照提示从下层一个个装就可以，按照c>b>a的顺序环形依赖：
a->b->c->a将三个包名写在一起，直接一次装模块依赖：用httpd举例
# 需要一些模块
[root@localhost Packages]# rpm -ivh httpd-2.4.6-17.el7.x86_64.rpm
warning: httpd-2.4.6-17.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
error: Failed dependencies:
/etc/mime.types is needed by httpd-2.4.6-17.el7.x86_64
httpd-tools = 2.4.6-17.el7 is needed by httpd-2.4.6-17.el7.x86_64
libapr-1.so.0()(64bit) is needed by httpd-2.4.6-17.el7.x86_64
libaprutil-1.so.0()(64bit) is needed by httpd-2.4.6-17.el7.x86_64
# 访问 http://www.rpmfind.net/ 去查找这个模块在哪个包中，安装那个包使用yum 安装软件包
什么是yum ： yellow dog update manage黄狗更新管理器
使用rpm安装yum
[root@master Packages]# rpm -ivh yum-3.4.3-118.el7.noarch.rpm
warning: yum-3.4.3-118.el7.noarch.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
Preparing... ################################# [100%]
package yum-3.4.3-118.el7.noarch is already installed- 配置yum源
###注：考试给一个http的连接给啥写啥###
# 将iso光盘挂在到/mnt目录上
sudo mount -o /dev/sr0 /mnt
# 查看目录挂载
[kane@master mnt]$ df -H
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/rhel-root 19G 3.3G 16G 18% /
devtmpfs 949M 0 949M 0% /dev
tmpfs 958M 152k 958M 1% /dev/shm
tmpfs 958M 9.4M 949M 1% /run
tmpfs 958M 0 958M 0% /sys/fs/cgroup
/dev/sda1 521M 125M 397M 24% /boot
/dev/sr0 3.8G 3.8G 0 100% /mnt
# 我们将iso中的package配置成yum源
sudo yum-config-manager --add-repo=file:///mnt
# 到 yum源目录下
[root@master request-key.d]# cd /etc/yum.repos.d/
# 追加内容gpgcheck=0。让其不检查
[root@master yum.repos.d]# echo "gpgcheck=0" >> ./mnt.repo
# 刷新缓存
[root@master yum.repos.d]# yum makechahe
- 安装与安装回滚
# 安装httpd
[root@master yum.repos.d]# yum install httpd
# 查看安装历史
[root@master yum.repos.d]# yum history
Loaded plugins: langpacks, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
ID | Login user | Date and time | Action(s) | Altered
-------------------------------------------------------------------------------
5 | kane <kane> | 2019-10-22 13:45 | Install | 5
history list
# 回滚某次安装 使用ID
[root@master yum.repos.d]# yum history undo 5
# 再次查看，会多一个抹去的操作
[root@master yum.repos.d]# yum history
Loaded plugins: langpacks, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
ID | Login user | Date and time | Action(s) | Altered
-------------------------------------------------------------------------------
6 | kane <kane> | 2019-10-22 13:47 | Erase | 5
5 | kane <kane> | 2019-10-22 13:45 | Install | 5
history list
# 此处看不到每个Id都是做什么的，我们可以查看yum安装log
[root@master yum.repos.d]# cat /var/log/yum.log
Oct 22 13:45:09 Installed: apr-1.4.8-3.el7.x86_64
Oct 22 13:45:09 Installed: apr-util-1.5.2-6.el7.x86_64
Oct 22 13:45:09 Installed: httpd-tools-2.4.6-17.el7.x86_64
Oct 22 13:45:09 Installed: mailcap-2.1.41-2.el7.noarch
Oct 22 13:45:11 Installed: httpd-2.4.6-17.el7.x86_64
Oct 22 13:47:04 Erased: httpd-2.4.6-17.el7.x86_64
Oct 22 13:47:04 Erased: httpd-tools-2.4.6-17.el7.x86_64
Oct 22 13:47:04 Erased: mailcap-2.1.41-2.el7.noarch
Oct 22 13:47:04 Erased: apr-util-1.5.2-6.el7.x86_64
Oct 22 13:47:05 Erased: apr-1.4.8-3.el7.x86_64- 软件包组
[root@master yum.repos.d]# yum groups list
Loaded plugins: langpacks, product-id, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
There is no installed groups file.
Maybe run: yum groups mark convert (see man yum)
Available environment groups:
Minimal Install
Infrastructure Server
File and Print Server
Basic Web Server
Virtualization Host
Server with GUI
Available Groups:
Compatibility Libraries
Console Internet Tools
Development Tools
Graphical Administration Tools
Legacy UNIX Compatibility
Scientific Support
Security Tools
Smart Card Support
System Administration Tools
System Management
Done