查看进程信息
1.1 问题
本例要求掌握查看进程信息的操作,使用必要的命令工具完成下列任务:
- 找出进程 gdm 的 PID 编号值
- 列出由进程 gdm 开始的子进程树结构信息
- 找出进程 sshd 的父进程的 PID 编号/进程名称
- 查看当前系统的CPU负载/进程总量信息
1.2 方案
查看进程的主要命令工具:
- ps aux、ps –elf:查看进程静态快照
- top:查看进程动态排名
- pstree:查看进程与进程之间的树型关系结构
- pgrep:根据指定的名称或条件检索进程
1.3 步骤
实现此案例需要按照如下步骤进行。
步骤一:找出进程 gdm 的 PID 编号值
使用pgrep命令查询指定名称的进程,选项-l显示PID号、-x精确匹配进程名:
- [[email protected] ~]# pgrep -lx gdm
- 1584 gdm
步骤二:列出由进程 gdm 开始的子进程树结构信息
使用pstree命令,可以提供用户名或PID值作为参数。通过前一步已知进程gdm的PID为1584,因此以下操作可列出进程gdm的进程树结构:
- [[email protected] ~]# pstree -p 1584
- gdm(1584)-+-Xorg(1703)
- |-gdm-session-wor(2670)-+-gnome-session(2779)-+-gnom+
- | | |-gnom+
- | | |-{gno+
- | | |-{gno+
- | | `-{gno+
- | |-{gdm-session-wor}(2678)
- | `-{gdm-session-wor}(2682)
- |-{gdm}(1668)
- |-{gdm}(1671)
- `-{gdm}(1702)
步骤三:找出进程 sshd 的父进程的 PID 编号/进程名称
要查看进程的父进程PID,可以使用ps –elf命令,简单grep过滤即可。找到进程sshd所在行对应到的PPID值即为其父进程的PID编号。为了方便直观查看,建议先列出ps表头行,以分号隔开再执行过滤操作。
- [[email protected] ~]# ps -elf | head -1 ; ps -elf | grep sshd
- F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD
- 4 S root 1362 1 0 80 0 - 20636 poll_s Jan05 ? 00:00:00 /usr/sbin/sshd –D
- .. .. //可获知进程sshd的父进程PID为1
然后再根据pstree –p的结果过滤,可获知PID为1的进程名称为systemd:
- [[email protected] ~]# pstree -p | grep ‘(1)‘
- systemd(1)-+-ModemManager(995)-+-{ModemManager}(1018)
步骤四:查看当前系统的CPU负载/进程总量信息
使用top命令,直接看开头部分即可;或者 top -n 次数:
- [[email protected] ~]# top
- top - 15:45:25 up 23:55, 2 users, load average: 0.02, 0.03, 0.05
- Tasks: 485 total, 2 running, 483 sleeping, 0 stopped, 0 zombie
- %Cpu(s): 1.7 us, 1.0 sy, 0.0 ni, 97.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
- KiB Mem : 1001332 total, 76120 free, 419028 used, 506184 buff/cache
- KiB Swap: 2097148 total, 2096012 free, 1136 used. 372288 avail Mem
- .. ..
观察Tasks: 485 total部分,表示进程总量信息。
观察load average: 0.02, 0.03, 0.05 部分,表示CPU处理器在最近1分钟、5分钟、15分钟内的平均处理请求数(对于多核CPU,此数量应除以核心数)。
对于多核CPU主机,如果要分别显示每颗CPU核心的占用情况,可以在top界面按数字键1进行切换:
- [[email protected] ~]# top
- top - 15:47:45 up 23:57, 2 users, load average: 0.02, 0.03, 0.05
- Tasks: 485 total, 2 running, 269 sleeping, 0 stopped, 1 zombie
- Cpu0 : 0.6%us, 7.8%sy, 0.0%ni, 91.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
- Cpu1 : 0.7%us, 3.7%sy, 0.0%ni, 95.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
- Cpu2 : 0.7%us, 1.7%sy, 0.0%ni, 97.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
- Cpu3 : 0.3%us, 1.0%sy, 0.0%ni, 98.3%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st
- Mem: 16230564k total, 15716576k used, 513988k free, 326124k buffers
- Swap: 8388604k total, 220656k used, 8167948k free, 11275304k cached
- .. ..
2 案例2:进程调度及终止
2.1 问题
本例要求掌握调度及终止进程的操作,使用必要的工具完成下列任务:
- 运行“sleep 600”命令,再另开一个终端,查出sleep程序的PID并杀死
- 运行多个vim程序并都放入后台,然后杀死所有vim进程
- su切换为zhsan用户,再另开一个终端,强制踢出zhsan用户
2.2 方案
进程调度及终止的主要命令工具:
- 命令行 &:将命令行在后台运行
- Ctrl + z 组合键:挂起当前进程(暂停并转入后台)
- jobs:列出当前用户当前终端的后台任务
- bg 编号:启动指定编号的后台任务
- fg 编号:将指定编号的后台任务调入前台运行
- kill [-9] PID...:杀死指定PID值的进程
- kill [-9] %n:杀死第n个后台任务
- killall [-9] 进程名...:杀死指定名称的所有进程
- pkill:根据指定的名称或条件杀死进程
2.3 步骤
实现此案例需要按照如下步骤进行。
步骤一:根据PID杀死进程
1)开启sleep测试进程
- [[email protected] ~]# sleep 600
- //.. .. 进入600秒等待状态
2)找出进程sleep的PID
另开一个终端,ps aux并过滤进程信息(第2列为PID值):
- [[email protected] ~]# ps aux | grep sleep
- root 32929 0.0 0.0 4312 360 pts/1 S+ 17:25 0:00 sleep 600
3)杀死指定PID的进程
- [[email protected] ~]# kill -9 32929
返回原终端会发现sleep进程已经被杀死:
- [[email protected] ~]# sleep 600
- Killed
步骤二:根据进程名杀死多个进程
1)在后台开启多个vim进程
- [[email protected] ~]# vim a.txt &
- [1] 33152
- [[email protected] ~]# vim b.txt &
- [2] 33154
- [1]+ 已停止 vim a.txt
- [[email protected] ~]# vim c.txt &
- [3] 33155
- [2]+ 已停止 vim b.txt
2)确认vim进程信息
- [[email protected] ~]# jobs -l
- [1] 33152 停止 (tty 输出) vim a.txt
- [2]- 33154 停止 (tty 输出) vim b.txt
- [3]+ 33155 停止 (tty 输出) vim c.txt
3)强制杀死所有名为vim的进程
- [[email protected] ~]# killall -9 vim
- [1] 已杀死 vim a.txt
- [2]- 已杀死 vim b.txt
- [3]+ 已杀死 vim c.txt
4)确认杀进程结果
- [[email protected] ~]# jobs -l
- [[email protected] ~]#
步骤三:杀死属于指定用户的所有进程
1)登入测试用户zhsan
- [[email protected] ~]# useradd zhsan
- [[email protected] ~]# su - zhsan
- [[email protected] ~]$
2)另开一个终端,以root用户登入,查找属于用户zhsan的进程
- [[email protected] ~]# pgrep -u zhsan
- 33219
- [[email protected] ~]# pstree -up 33219 //检查进程树
- bash(33219,zhsan)
3)强制杀死属于用户zhsan的进程
- [[email protected] ~]# pkill -9 -u zhsan
- [[email protected] ~]#
4)返回原来用户zhsan登录的终端,确认已经被终止
- [[email protected] ~]$ 已杀死
- [[email protected] ~]#
3 案例3:系统日志分析
3.1 问题
本例要求熟悉Linux系统中的常见日志文件,使用必要的命令工具完成下列任务:
- 列出所有包含关键词8909的系统日志消息
- 查看启动时识别的鼠标设备信息
- 列出最近2条成功/不成功的用户登录消息
- 列出最近10条重要程度在 ERR 及以上的日志消息
- 列出所有与服务httpd相关的消息
- 列出前4个小时内新记录的日志
3.2 方案
常见的系统日志及各自用途:
- /var/log/messages,记录内核消息、各种服务的公共消息
- /var/log/dmesg,记录系统启动过程的各种消息
- /var/log/cron,记录与cron计划任务相关的消息
- /var/log/maillog,记录邮件收发相关的消息
- /var/log/secure,记录与访问限制相关的安全消息
日志消息的优先级(高-->低):
- EMERG(紧急):级别0,系统不可用的情况
- ALERT(警报):级别1,必须马上采取措施的情况
- CRIT(严重):级别2,严重情形
- ERR(错误):级别3,出现错误
- WARNING(警告):级别4,值得警告的情形
- NOTICE(注意):级别5,普通但值得引起注意的事件
- INFO(信息):级别6,一般信息
- DEBUG(调试):级别7,程序/服务调试消息
RHEL7提供的journalctl日志工具的常见用法:
- journalctl | grep 关键词
- journalctl -u 服务名 -p 优先级
- journalctl -n 消息条数
- journalctl --since="yyyy-mm-dd HH:MM:SS" --until="yyyy-mm-dd HH:MM:SS"
3.3 步骤
实现此案例需要按照如下步骤进行。
步骤一:分析系统日志及用户日志
1)列出所有包含关键词8909的系统日志消息
简单模拟一个故障(SELinux阻止Web开放8909端口):
- [[email protected] ~]# vim /etc/httpd/conf.d/8909.conf //添加开8909端口配置
- Listen 8909
- [[email protected] ~]# setenforce 1 //开启强制模式
- [[email protected] ~]# systemctl restart httpd //起服务失败
- Job for httpd.service failed because the control process exited with error code. See "systemctl status httpd.service" and "journalctl -xe" for details.
从日志文件/var/log/messages中检索信息:
- [[email protected] ~]# grep 8909 /var/log/messages
- Jan 6 17:53:48 svr7 setroubleshoot: SELinux is preventing /usr/sbin/httpd from name_bind access on the tcp_socket port 8909. For complete SELinux messages. run sealert -l 6d37b8f0-ab8a-4082-9295-c784f4f57190
- Jan 6 17:53:48 svr7 python: SELinux is preventing /usr/sbin/httpd from name_bind access on the tcp_socket port 8909.#012#012***** Plugin bind_ports (92.2 confidence) suggests ************************#012#012If you want to allow /usr/sbin/httpd to bind to network port 8909#012Then you need to modify the port type.#012Do#012# semanage port -a -t PORT_TYPE -p tcp 8909#012 where PORT_TYPE is one of the following: http_cache_port_t, http_port_t, jboss_management_port_t, jboss_messaging_port_t, ntop_port_t, puppet_port_t.#012#012***** Plugin catchall_boolean (7.83 confidence) suggests ******************#012#012If you want to allow nis to enabled#012Then you must tell SELinux about this by enabling the ‘nis_enabled‘ boolean.#012#012Do#012setsebool -P nis_enabled 1#012#012***** Plugin catchall (1.41 confidence) suggests **************************#012#012If you believe that httpd should be allowed name_bind access on the port 8909 tcp_socket by default.#012Then you should report this as a bug.#012You can generate a local policy module to allow this access.#012Do#012allow this access for now by executing:#012# grep httpd /var/log/audit/audit.log | audit2allow -M mypol#012# semodule -i mypol.pp#012
- .. ..
使用完毕记得删除测试配置文件:
- [[email protected] ~]# rm -rf /etc/httpd/conf.d/8909.conf
- [[email protected] ~]# systemctl restart httpd
2)查看启动时识别的鼠标设备信息
- [[email protected] ~]# dmesg | grep -i mouse
- [ 1.020385] mousedev: PS/2 mouse device common for all mice
- [ 1.249422] input: ImPS/2 Generic Wheel Mouse as /devices/platform/i8042/serio1/input/input2
- [ 2.279665] usb 2-1: Product: VMware Virtual USB Mouse
- [ 2.603999] input: VMware VMware Virtual USB Mouse as /devices/pci0000:00/0000:00:11.0/0000:02:00.0/usb2/2-1/2-1:1.0/input/input3
- [ 2.604222] hid-generic 0003:0E0F:0003.0001: input,hidraw0: USB HID v1.10 Mouse [VMware VMware Virtual USB Mouse] on usb-0000:02:00.0-1/input0
3)列出最近2条成功/不成功的用户登录消息
查看成功登录的事件消息:
- [[email protected] ~]# last -2
- zhsan pts/2 192.168.4.207 Fri Jan 6 18:00 - 18:00 (00:00)
- root pts/2 192.168.4.110 Fri Jan 6 17:26 - 17:59 (00:33)
- wtmp begins Thu Aug 4 00:10:16 2016
查看失败登录的事件消息:
- [[email protected] ~]# lastb -2
- anonymou ssh:notty 192.168.4.207 Fri Jan 6 18:00 - 18:00 (00:00)
- anonymou ssh:notty 192.168.4.207 Fri Jan 6 18:00 - 18:00 (00:00)
- btmp begins Fri Jan 6 18:00:34 2017
步骤二:使用journalctl日志提取工具
1)列出最近10条重要程度在 ERR 及以上的日志消息
- [[email protected] ~]# journalctl -p err -n 10
- -- Logs begin at Thu 2017-01-05 15:50:08 CST, end at Fri 2017-01-06 18:01:01 CST. --
- Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from getattr access on the file /rhel7/repodata/repomd.xml. For complete SELinux mes
- Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from read access on the file repomd.xml. For complete SELinux messages. run sealert
- Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from read access on the file repomd.xml. For complete SELinux messages. run sealert
- Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from lock access on the file /rhel7/repodata/repomd.xml. For complete SELinux messag
- Jan 06 17:53:48 svr7 setroubleshoot[33743]: Plugin Exception restorecon_source
- Jan 06 17:53:48 svr7 setroubleshoot[33743]: SELinux is preventing /usr/sbin/httpd from name_bind access on the tcp_socket port 8909. For complete SELinux messages. run
- Jan 06 17:53:53 svr7 setroubleshoot[33743]: SELinux is preventing /usr/sbin/httpd from name_connect access on the tcp_socket port 8909. For complete SELinux messages.
- Jan 06 17:53:54 svr7 systemd[1]: Failed to start The Apache HTTP Server.
- .. ..
- lines 1-11/11 (END)
2)列出所有与服务httpd相关的消息
- [[email protected] ~]# journalctl -u httpd
- -- Logs begin at Thu 2017-01-05 15:50:08 CST, end at Fri 2017-01-06 18:01:01 CST. --
- Jan 06 14:57:16 svr7 systemd[1]: Starting The Apache HTTP Server...
- Jan 06 14:57:16 svr7 httpd[23812]: AH00557: httpd: apr_sockaddr_info_get() failed for svr7
- Jan 06 14:57:16 svr7 httpd[23812]: AH00558: httpd: Could not reliably determine the server‘s fully qualified domain name, using 127.0.0.1. Set the ‘ServerName‘ directi
- Jan 06 14:57:16 svr7 systemd[1]: Started The Apache HTTP Server.
- Jan 06 17:53:44 svr7 systemd[1]: Stopping The Apache HTTP Server...
- Jan 06 17:53:46 svr7 systemd[1]: Starting The Apache HTTP Server...
- Jan 06 17:53:46 svr7 httpd[33741]: AH00557: httpd: apr_sockaddr_info_get() failed for svr7
- .. ..
3)列出前4个小时内新记录的日志
根据当前日期时间往前推4个小时,确定--since起始和--until结束时刻:
- [[email protected] ~]# journalctl --since "2017-01-06 14:11" --until "2017-01-06 18:11"
- -- Logs begin at Thu 2017-01-05 15:50:08 CST, end at Fri 2017-01-06 18:10:01 CST. --
- Jan 06 14:20:01 svr7 systemd[1]: Started Session 160 of user root.
- Jan 06 14:20:01 svr7 CROND[22869]: (root) CMD (/usr/lib64/sa/sa1 1 1)
- Jan 06 14:20:01 svr7 systemd[1]: Starting Session 160 of user root.
- Jan 06 14:30:01 svr7 systemd[1]: Started Session 161 of user root.
- Jan 06 14:30:01 svr7 CROND[23028]: (root) CMD (/usr/lib64/sa/sa1 1 1)
- Jan 06 14:31:39 svr7 systemd[1]: Starting Session 162 of user root.
- Jan 06 14:32:17 svr7 sshd[23046]: pam_unix(sshd:session): session closed for user root
- Jan 06 14:31:39 svr7 systemd[1]: Started Session 162 of user root.
- Jan 06 14:31:39 svr7 sshd[23046]: pam_unix(sshd:session): session opened for user root by (uid=0)
- Jan 06 14:31:39 svr7 systemd-logind[985]: New session 162 of user root.
- .. .
4 案例4:使用systemctl工具
4.1 问题
本例要求掌握systemctl控制工具的基本操作,完成下列任务:
- 重启 httpd、crond、bluetooth 服务,查看状态
- 禁止 bluetooth 服务开机自启,并停用此服务
- 设置默认级别为 multi-user.target 并确认
4.2 方案
systemd是一个更高效的系统&服务管理器,其相关特性如下:
- 开机服务并行启动,各系统服务间的精确依赖
- 配置目录:/etc/systemd/system/
- 服务目录:/lib/systemd/system/
systemctl是systemd的管理工具,将相关资源组织为unit配置单元进行管理。
不同的unit决定了一组相关的启动任务,service和target是最常用的配置单元:
- service:后台独立服务
- target:一套配置单元的组合,类似于传统“运行级别”
4.3 步骤
实现此案例需要按照如下步骤进行。
步骤一:重启 httpd、crond、bluetooth 服务,查看状态
1)重启系统服务httpd、crond、bluetooth
- [[email protected] ~]# systemctl restart httpd crond bluetooth
2)查看上述服务的状态
- [[email protected] ~]# systemctl status httpd crond bluetooth
- * httpd.service - The Apache HTTP Server
- Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
- Active: active (running) since Fri 2017-01-06 18:18:20 CST; 18s ago
- .. ..
- * crond.service - Command Scheduler
- Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
- Active: active (running) since Fri 2017-01-06 18:18:19 CST; 19s ago
- .. ..
- * bluetooth.service - Bluetooth service
- Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; vendor preset: enabled)
- Active: active (running) since Fri 2017-01-06 18:18:19 CST; 19s ago
- .. ..
步骤二:禁止 bluetooth 服务开机自启,并停用此服务
1)停用bluetooth服务
- [[email protected] ~]# systemctl stop bluetooth
2)禁止bluetooth服务开机自启
- [[email protected] ~]# systemctl disable bluetooth
- Removed symlink /etc/systemd/system/dbus-org.bluez.service.
- Removed symlink /etc/systemd/system/bluetooth.target.wants/bluetooth.service.
- [[email protected] ~]# systemctl is-enabled Bluetooth //检查结果
- disabled
步骤三:设置默认级别为 multi-user.target 并确认
1)查看默认运行级别
- [[email protected] ~]# systemctl get-default
- graphical.target
2)将默认运行级别设置为multi-user.target
- [[email protected] ~]# systemctl set-default multi-user.target
- Removed symlink /etc/systemd/system/default.target.
- Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/multi-user.target.
3)确认配置结果
- [[email protected] ~]# systemctl get-default
- multi-user.target