用户权限

[root@oldboyedu59 ~]# grep oldboy /etc/sudoers
oldboy  ALL=(ALL)       /bin/ls, /bin/touch

[oldboy@oldboyedu59 ~]$ sudo -l
[sudo] password for oldboy: 

User oldboy may run the following commands on oldboyedu59:
   (ALL) /bin/ls, /bin/touch
[oldboy@oldboyedu59 ~]$ ls /root/
ls: cannot open directory /root/: Permission denied
[oldboy@oldboyedu59 ~]$ sudo ls /root/
alex  anaconda-ks.cfg  dir-032  dir-035  file-032  file-035  oldboydir  oldboy.txt  pass.txt  passwd.txtdd2  sed.sed 

sudo练习题 :
给oldboy配置sudo可以查看系统的日志 （思考查看日志有什么命令）

/bin/grep, /bin/head, /bin/tail, /bin/less, /bin/more, /bin/cat
[root@oldboyedu59 ~]# grep oldboy /etc/sudoers

oldboy ALL=(ALL) /bin/ls, /bin/touch

oldboy ALL=(ALL) /bin/grep, /bin/head, /bin/tail, /bin/less, /bin/more, /bin/cat

给oldboy配置可以运行/bin下面所有命令
oldboy  ALL=(ALL)        /bin/*

给oldboy配置可以运行/bin下面所有命令但是不能使用vi和su 
oldboy  ALL=(ALL)        /bin/*, !/bin/vi, !/bin/su, !/bin/rm

给oldboy配置可以运行系统中所有命令并且不需要再输入oldboy密码

oldboy  ALL=(ALL)       NOPASSWD: ALL

 



排错能力:[故障集合]Linux必备故障及原因50个

https://www.jianshu.com/p/99ec5bb4183f

[root@oldboyedu59 ~]# ll /var/log/messages* /var/log/secure* /var/log/cron*
-rw------- 1 root root 8767 Apr 26 11:01 /var/log/cron
-rw-------. 1 root root 13697 Apr 22 09:36 /var/log/cron-20190422
-rw------- 1 root root 268052 Apr 26 11:01 /var/log/messages
-rw-------. 1 root root 790356 Apr 22 09:36 /var/log/messages-20190422
-rw------- 1 root root 23140 Apr 26 10:42 /var/log/secure
-rw-------. 1 root root 17169 Apr 22 08:48 /var/log/secure-20190422

定时的切割
系统定时对系统日志 进行切割（日志切割/日志轮询） 防止单个日志过大

 [root@oldboyedu59 ~]# ll /etc/cron.daily/
total 8
-rwx------. 1 root root 219 Oct 31 03:12 logrotate
-rwxr-xr-x. 1 root root 618 Oct 30 22:55 man-db.cron
[root@oldboyedu59 ~]# cat /etc/logrotate.d/syslog 
/var/log/cron
/var/log/maillog
/var/log/messages
/var/log/secure
/var/log/spooler
{
    missingok
    sharedscripts
    postrotate
    /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}

每天8:30 开始上课（go to school)
30 08 * * * go to school

每天晚上12点带远导去 dbj
每个月的1号晚上11点带guoav去看av （kan）
0 2 * * 1 /data/postmall/shell/a.sh表示什么含义？

每天晚上12点带远导去 dbj

• 00 * * * dbj #半夜12点00到半夜12点59分 每分钟一次
  00 00 * * * dbj #每天的半夜12点整

每个月的1号晚上11点带guoav去看av （kan）
00 23 01 * * kan

0 2 * * 1 /data/postmall/shell/a.sh表示什么含义？
每周1的凌晨2点整 执行脚本

定时任务特殊符号:

1. • 每
2. /

• • • • • echo oldboy >>/tmp/oldboy.txt
          */1 * * * * echo oldboy >>/tmp/oldboy.txt

日志中只能显示 定时任务是否运行 无法查看是否出错

Apr 26 12:32:01 oldboyedu59 CROND[7921]: (root) CMD (date >>/tmp/time.log)
Apr 26 12:34:01 oldboyedu59 CROND[7926]: (root) CMD (date >>/tmp/time.log)
Apr 26 12:36:01 oldboyedu59 CROND[7930]: (root) CMD (date >>/tmp/time.log)
Apr 26 12:38:01 oldboyedu59 CROND[7935]: (root) CMD (date >>/tmp/time.log)
Apr 26 12:40:01 oldboyedu59 CROND[7950]: (root) CMD (date >>/tmp/time.log)

什么时间 root用户的定时任务 CMD 执行的命令或脚本

今日提示集合：

 "/etc/sudoers.tmp" 125L, 4588C written
>>> /etc/sudoers: syntax error near line 105 <<<
                  语法错误 在105行
                  
[sudo] password for oldboy: 
Sorry, user oldboy may not run sudo on oldboyedu59. 

[root@oldboyedu59 ~]# crontab -l
no crontab for root
root用户没有定时任务 

2.no crontab for root - using an empty one
root用户没有定时任务 创建1个空的文件

3.crontab: installing new crontab
           更新定时任务规则 

mei liangfenzhong xianshi xitong shijian zhuijiadao /tmp/oldboy.txt

* /1 * * * date  >>/tmp/oldboy.txt

"/tmp/crontab.5UZIdI" 3L, 115C written
crontab: installing new crontab
"/tmp/crontab.5UZIdI":3: bad hour
errors in crontab file, can't install.
Do you want to retry the same edit?

*/1 * * * * date >>/tmp/oldboy.txt