Offline exercises Chapter 11
Basic class
1. Edit a 1 Txt file, as follows
cat >>1.txt <<EOF 10.0.3.1 00:0F:AF:81:19:1F 10.0.3.2 00:0F:AF:85:6C:25 10.0.3.3 00:0F:AF:85:70:42 10.0.2.20 00:0F:AF:85:55:DE 10.0.2.21 00:0F:AF:85:6C:09 10.0.2.22 00:0F:AF:85:5C:41 10.0.0.151 00:0F:AF:85:6C:F6 10.0.0.152 00:0F:AF:83:1F:65 10.0.0.153 00:0F:AF:85:70:03 10.0.1.10 00:30:15:A2:3B:B6 10.0.1.11 00:30:15:A3:23:B7 10.0.1.12 00:30:15:A2:3A:A1 10.0.1.1 00:0F:AF:81:19:1F 10.0.2.2 00:0F:AF:85:6C:25 10.0.3.3 00:0F:AF:85:70:42 10.0.2.20 00:0F:AF:85:55:DE 10.0.1.21 00:0F:AF:85:6C:09 10.0.2.22 00:0F:AF:85:5C:41 10.0.0.151 00:0F:AF:85:6C:F6 10.0.1.152 00:0F:AF:83:1F:65 10.0.0.153 00:0F:AF:85:70:03 10.0.3.10 00:30:15:A2:3B:B6 10.0.1.11 00:30:15:A3:23:B7 10.0.3.12 00:30:15:A2:3A:A1 EOF
(1) Sort the output of the file (prompt: sort by the first character in the third column and all characters in the fourth column)
[root@Magedu ~]#
[root@Magedu ~]# awk -F '[. ]' '{print $3,$4}' 1.txt | sort -n
0 151
0 151
0 152
...
[root@Magedu ~]# #-k specifies the fields to be sorted
[root@Magedu ~]# #sort -t "." -k4.1,4.3 with '.' To separate and sort from the head of the fourth column to the end of the fourth column.
[root@Magedu ~]# sort -t "." -k3.1,3.1 -n -k4.1,4.3 -n 1.txt
10.0.0.151 00:0F:AF:85:6C:F6
10.0.0.151 00:0F:AF:85:6C:F6
10.0.0.152 00:0F:AF:83:1F:65
...
[root@Magedu ~]#
(2) Filter all letters of the file, case insensitive
[root@Magedu ~]# [root@Magedu ~]# grep -i '[a-z]' 1.txt 10.0.3.1 00:0F:AF:81:19:1F 10.0.3.2 00:0F:AF:85:6C:25 10.0.3.3 00:0F:AF:85:70:42 ... [root@Magedu ~]#
(3) Filter out lines ending with the number 3
[root@Magedu ~]# [root@Magedu ~]# grep '3$' 1.txt 10.0.0.153 00:0F:AF:85:70:03 10.0.0.153 00:0F:AF:85:70:03 [root@Magedu ~]#
2. Upload "web3_access.log" to your linux server
(1) Count the number of IP addresses of the file and sort them in positive order
[root@Magedu ~]#
[root@Magedu ~]# awk '{print $1}' web3_access.log | sort | uniq -c | sort -n
1 72.0.16.28
1 172.18.118.99
1 172.20.111.149
2 172.16.101.126
...
[root@Magedu ~]#
(2) Count the number of HTTP status return codes in the file (for example, 200404403, in the ninth column) and sort them in reverse order
[root@Magedu ~]#
[root@Magedu ~]# awk '{print $9}' web3_access.log | sort | uniq -c | sort -nr
1 91748
3 501
...
22893 206
23395 200
[root@Magedu ~]#
(3) Filter out all lines whose status return code is 200, and replace all lines whose return code is 200 with 300
[root@Magedu ~]#
[root@Magedu ~]# awk '{print $9}' web3_access.log | grep '200' | sed 's#200#300#g'
300
300
300
...
[root@Magedu ~]# #grep -o displays only the part of the matched row that matches PATTERN.
[root@Magedu ~]# grep -o '200' web3_access.log |sed 's#200#300#g'
[root@Magedu ~]#
3. Match the line containing the root keyword in / etc/passwd (at least two methods are required, awk and grep respectively)
[root@Magedu ~]# [root@Magedu ~]# awk -p '/root/' /etc/passwd root:x:0:0:root:/root:/bin/bash operator:x:11:0:operator:/root:/sbin/nologin [root@Magedu ~]# [root@Magedu ~]# [root@Magedu ~]# grep 'root' /etc/passwd root:x:0:0:root:/root:/bin/bash operator:x:11:0:operator:/root:/sbin/nologin [root@Magedu ~]#
4. Take the ":" as the separator and take out the contents of the last column of the first row of / etc/passwd
[root@Magedu ~]#
[root@Magedu ~]# awk -F ':' '{print $NF}' /etc/passwd | awk 'NR==1'
/bin/bash
[root@Magedu ~]# awk -F ":" 'NR==1 {print $NF}' /etc/passwd
[root@Magedu ~]#
5. Take out the column with ":" as the separator and the third column (user UID) ending with 0
[root@Magedu ~]#
[root@Magedu ~]# awk -F ':' '{print $3}' /etc/passwd | grep '0$'
0
990
70
1000
[root@Magedu ~]#
6. Create new users u1 and u2. The password is redhat and belongs to the same additional group grp1. User u2 is not allowed to log in to the system
[root@Magedu ~]# [root@Magedu ~]# groupadd grp1 [root@Magedu ~]# useradd -G grp1 u1 [root@Magedu ~]# useradd -G grp1 u2 [root@Magedu ~]# usermod -s /sbin/nologin u2 [root@Magedu ~]# echo redhat | passwd --stdin u1 Change user u1 Your password. passwd: All authentication tokens have been successfully updated. [root@Magedu ~]# echo redhat | passwd --stdin u2 Change user u2 Your password. passwd: All authentication tokens have been successfully updated. [root@Magedu ~]#
7. View uid and gid information of user u1
[root@Magedu ~]# [root@Magedu ~]# id u1 uid=1007(u1) gid=1008(u1) group=1008(u1),1007(grp1) [root@Magedu ~]#
8. Create group distro with GID 2019
[root@Magedu ~]# [root@Magedu ~]# groupadd -g 2019 distro [root@Magedu ~]# [root@Magedu ~]# tail -n1 /etc/group distro:x:2019: [root@Magedu ~]#
9. Create user magedudir with ID number of 1005 and basic group of distro
[root@Magedu ~]# [root@Magedu ~]# useradd -u 1005 -g 2019 magedudir [root@Magedu ~]# [root@Magedu ~]# id magedudir uid=1005(magedudir) gid=2019(distro) group=2019(distro) [root@Magedu ~]#
10. Add a password to user mageduman. The password is mageduboyedu
[root@Magedu ~]# [root@Magedu ~]# echo mageduboyedu | passwd --stdin magedudir Change user magedudir Your password. passwd: All authentication tokens have been successfully updated. [root@Magedu ~]#
Process class
1. Use ps to view the process and explain the meaning of R, S, D, Z and T in the process status
[root@Magedu ~]# ps aux R Process running s A process is a control process, Ss Process leader, parent process S Interruptible sleep < The process runs on a high priority, S<Higher priority processes T The process is paused N The process runs on a low priority, SN Lower priority processes D Non interruptible process + The current process is running in the foreground, R+Indicates that the process is running in the foreground Z Zombie process l The process is multithreaded, Sl Indicates that the process is running as a thread
2. Install an nginx using yum and start it to view the details of the nginx process
[root@Magedu /]# [root@Magedu /]# yum install nginx Repository extras is listed more than once in the configuration Last metadata expiration check: 0:00:48 It was executed at 19:49:17 on Tuesday, July 27, 2021. Dependency resolution. ... complete! [root@Magedu /]# [root@Magedu /]# systemctl start nginx [root@Magedu /]# [root@Magedu /]# ps aux | grep nginx root 2322 0.0 0.0 46472 1140 ? Ss 17:48 0:00 nginx: master process /usr/sbin/ngin -c /etc/nginx/nginx.conf nginx 2323 0.0 0.1 48952 2248 ? S 17:48 0:00 nginx: worker process root 4650 0.0 0.0 112728 972 pts/0 S+ 19:30 0:00 grep --color=auto nginx [root@Magedu /]#
3. Open two xshell terminals to connect to the same virtual machine. One terminal enters the command "yum update", the other terminal checks the status of the yum command, the other terminal enters "yum install -y mariadb", and then checks the status of the yum command. When the yum command is completed, check the status of the yum command again.
[root@Magedu /]# [root@Magedu /]# yum update -y Plug in loaded: fastestmirror, langpacks Loading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.aliyun.com ... [root@Magedu /]# [root@Magedu /]# [root@Magedu /]# ps aux |grep yum root 2549 105 8.5 497324 159988 pts/1 R+ 05:46 0:07 /usr/bin/python /usr/bin/yum update -y root 2552 0.0 0.0 112728 972 pts/0 R+ 05:46 0:00 grep --color=auto yum [root@Magedu /]# [root@Magedu /]# [root@Magedu /]# ps aux |grep yum root 2557 0.0 0.0 112728 972 pts/0 S+ 05:46 0:00 grep --color=auto yum [root@Magedu /]# ------------------------------------------------------------ [root@Magedu /]# [root@Magedu /]# yum install -y mariadb Plug in loaded: fastestmirror, langpacks Loading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.aliyun.com ... [root@Magedu /]# [root@Magedu /]# [root@Magedu /]# ps aux |grep yum root 2655 98.0 5.6 434552 104944 pts/0 R+ 05:52 0:01 /usr/bin/python /usr/bin/yum install -y mariadb root 2658 0.0 0.0 112728 972 pts/1 S+ 05:52 0:00 grep --color=auto yum [root@Magedu /]# [root@Magedu /]# [root@Magedu /]# ps aux |grep yum root 2660 0.0 0.0 112728 972 pts/0 S+ 05:52 0:00 grep --color=auto yum [root@Magedu /]#
4. Use "vim test.c" to edit the code as follows
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[])
{
pid_t pid;
pid = fork();
if (pid == 0) {
int iPid = (int)getpid();
fprintf(stderr,"I am child,%d\n",iPid);
sleep(1);
fprintf(stderr, "Child exits\n");
return EXIT_SUCCESS;
}
int iPid = (int)getpid();
fprintf(stderr,"I am parent,%d\n",iPid);
fprintf(stderr, "sleep....\n");
sleep(600);
fprintf(stderr, "parent exits\n");
return EXIT_SUCCESS;
}
Then use "gcc test.c" to compile this code. A.out file will be generated in the current directory. Use ". / a.out" to execute the file (if there is no gcc command, use yum to install)
(1) Open a new terminal and use the top command to check the process status and whether there is a zombie process
[root@Magedu ~]# [root@Magedu ~]# gcc test.c [root@Magedu ~]# [root@Magedu ~]# ./a.out I am parent,2813 sleep.... I am child,2814 Child exits [root@Magedu ~]# [root@Magedu ~]# top ... PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2898 root 20 0 162028 2332 1588 R 0.3 0.1 0:00.06 top 2868 root 20 0 0 0 0 Z 0.0 0.0 0:00.00 a.out 2867 root 20 0 4212 348 276 S 0.0 0.0 0:00.00 a.out 2838 root 20 0 123264 736 508 S 0.0 0.0 0:00.00 anacron ... [root@Magedu ~]#
(2) Use the ps command to view the status of the zombie process
[root@Magedu ~]# [root@Magedu ~]# ps aux | grep out root 2867 0.0 0.0 4212 348 pts/1 S+ 06:02 0:00 ./a.out root 2868 0.0 0.0 0 0 pts/1 Z+ 06:02 0:00 [a.out] <defunct> root 2884 0.0 0.0 112728 972 pts/0 S+ 06:03 0:00 grep --color=auto out [root@Magedu ~]#
(3) Use the kill command to try to terminate the zombie process (do not use the - 9 parameter to force termination), and then check the status of the process to see if it can be terminated
[root@Magedu ~]# [root@Magedu ~]# ps -ef |grep out root 4869 4788 0 19:37 pts/0 00:00:00 ./a.out root 4870 4869 0 19:37 pts/0 00:00:00 [a.out] <defunct> root 4872 4705 0 19:37 pts/2 00:00:00 grep --color=auto out [root@Magedu ~]# [root@Magedu ~]# kill 4870 [root@Magedu ~]# [root@Magedu ~]# ps -ef |grep out root 4869 4788 0 19:37 pts/0 00:00:00 ./a.out root 4870 4869 0 19:37 pts/0 00:00:00 [a.out] <defunct> root 4874 4705 0 19:37 pts/2 00:00:00 grep --color=auto out [root@Magedu ~]#
(4) Kill the parent process of the zombie process and check whether the process is terminated
[root@Magedu ~]# [root@Magedu ~]# ps -ef |grep out root 4852 4788 0 19:36 pts/0 00:00:00 ./a.out root 4853 4852 0 19:36 pts/0 00:00:00 [a.out] <defunct> root 4855 4705 0 19:37 pts/2 00:00:00 grep --color=auto out [root@Magedu ~]# [root@Magedu ~]# kill 4852 [root@Magedu ~]# [root@Magedu ~]# ps -ef |grep out root 4866 4705 0 19:37 pts/2 00:00:00 grep --color=auto out [root@Magedu ~]#
5. Enter the top command to explain the meaning represented by each line and column of the first six lines (not an empty line)
[root@Magedu ~]# [root@Magedu ~]# top top - 06:04:37 up 44 min, 2 users, load average: 0.00, 0.01, 0.05 Tasks: 169 total, 1 running, 167 sleeping, 0 stopped, 1 zombie %Cpu(s): 0.0 us, 0.2 sy, 0.0 ni, 99.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 1863104 total, 392584 free, 418152 used, 1052368 buff/cache KiB Swap: 2097148 total, 2097148 free, 0 used. 1275348 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 root 20 0 191240 4320 2640 S 0.0 0.2 0:03.76 systemd ... [root@Magedu ~]# #The first line top - 06:04:37 up 44 min, 2 users, load average: 0.00, 0.01, 0.05 Task queue information, the same as uptime The execution result of the command. 06:04:37 Current time up 44 min System running time in the format of:Points 2 users Number of currently logged in users load average: 0.00, 0.01, 0.05 System load, that is, the average length of the task queue. The three values are the average values from 1 minute, 5 minutes and 15 minutes ago to now. #Tasks in the second line: 169 total, 1 running, 167 sleeping, 0 stopped, 1 zombie 169 total Total number of processes 1 running Number of running processes 167 sleeping Number of sleep processes 0 stopped Number of processes stopped 1 zombie Number of zombie processes. #The third line% CPU (s): 0.0 us, 0.2 sy, 0.0 Ni, 99.8 ID, 0.0 WA, 0.0 Hi, 0.0 Si, 0.0 st 0.0 us User space occupation CPU Percentage 0.2 sy Kernel space occupation CPU Percentage 0.0 ni Occupied by processes with changed priority in user process space CPU Percentage 99.8 id free CPU Percentage 0.0 wa Waiting for input and output CPU Percentage of time 0.0 hi Hard interrupt( Hardware IRQ)occupy CPU Percentage of 0.0 si Soft interrupt( Software Interrupts)occupy CPU Percentage of 0.0 st #Line 4 KIB MEM: 1863104 total, 392584 free, 418152 used, 1052368 buff / cache KiB Mem:1863104 total Total physical memory 392584 free Total free memory 418152 used Total physical memory used 1052368 buff/cache The amount of memory used as the kernel cache. #Line 5 KIB swap: 2097148 total, 2097148 free, 0 used 1275348 avail Mem KiB Swap:2097148 total Total exchange area 2097148 free Total free swap area 0 used. Total number of exchange areas used 1275348 avail Mem Represents the amount of physical memory available for the next allocation of the process cached Mem Total number of swap buffers. #Line 6 PID user PR Ni virt res SHR s% CPU% MEM time + command PID process ID, USER User name of the process owner PR Priority NI nice Value. Negative values indicate high priority, positive values indicate low priority VIRT The total amount of virtual memory used by the process, in kb. VIRT=SWAP+RES, RES The size of physical memory used by the process and not swapped out, unit kb. RES=CODE+DATA, SHR Shared memory size in kb, S Process status. D=Non interruptible sleep state R=function S=sleep T=track/stop it Z=Zombie process %CPU Last updated to now CPU Percentage of time occupied %MEM Percentage of physical memory used by the process TIME+ Used by the process CPU Total time in 1/100 Seconds COMMAND Command name/Command line. #------------Supplement------------ Listing meaning PID process id PPID Parent process id RUSER Real user name UID User of the process owner id USER User name of the process owner GROUP Group name of the process owner TTY The name of the terminal that started the process. Processes that are not started from the terminal are displayed as ? PR priority NI nice Value. Negative values indicate high priority and positive values indicate low priority P Last used CPU，Only in many CPU Meaningful in the environment %CPU Last updated to now CPU Time occupancy percentage TIME Used by the process CPU Total time in seconds TIME+ Used by the process CPU Total time in 1/100 second %MEM Percentage of physical memory used by the process VIRT The total amount of virtual memory used by the process, in kb. VIRT=SWAP+RES SWAP The size, unit, of the virtual memory used by the process kb RES The size of physical memory used by the process and not swapped out, unit kb. RES=CODE+DATA CODE Physical memory occupied by executable code, unit kb DATA Parts other than executable code(Data segment+Stack)Amount of physical memory occupied, in kb SHR Shared memory size in kb nFLT Number of page errors nDRT The number of pages that have been modified since the last write. S Process status. D=Non interruptible sleep state R=function S=sleep T=track/stop it Z=Zombie process COMMAND Command name/command line WCHAN If the process is sleeping, the system function name in sleep is displayed Flags Task flag
6. Open two terminals, enter the top command in one terminal, and the other terminal terminates the process to see the effect
[root@Magedu ~]#
[root@Magedu ~]# top
top - 21:39:26 up 16:34, 3 users, load average: 0.03, 0.02, 0.05
...
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1 root 20 0 125880 4180 2472 S 0.3 0.2 0:13.00 systemd
...
Killed
[root@Magedu ~]#
----------------------------------------------------------------------
[root@Magedu ~]# ps -ef | grep top
root 71164 59828 0 21:39 pts/5 00:00:00 top
root 71203 71112 0 21:39 pts/1 00:00:00 grep --color=auto top
[root@Magedu ~]#
[root@Magedu ~]# kill -9 71164
[root@Magedu ~]#
7. Enter the following command in linux "(while:; do uptime; sleep 1; done) &", open a new terminal to view the status of the process and try to terminate the process
[root@Magedu ~]# [root@Magedu ~]# ps aux | grep sleep root 3319 0.0 0.0 107956 612 ? S 06:17 0:00 sleep 60 root 3406 0.0 0.0 107956 612 pts/0 S 06:18 0:00 sleep 1 root 3408 0.0 0.0 112728 972 pts/1 S+ 06:18 0:00 grep --color=auto sleep [root@Magedu ~]# [root@Magedu ~]# pkill -9 -t pts/0 [root@Magedu ~]# [root@Magedu ~]# ps aux | grep sleep root 3319 0.0 0.0 107956 612 ? S 06:17 0:00 sleep 60 root 3434 0.0 0.0 112728 968 pts/1 S+ 06:18 0:00 grep --color=auto sleep [root@Magedu ~]#