Because I am new to shell scripts, I can only keep counting shell scripts that are different from mobile phones. The level is limited. I hope it can help everyone. If there are mistakes, please point them out in time, and we will make progress together, (#^.^#).

1. Shell script to configure the environment

systemctl stop firewalld

systemctl disable firewalld

systemctl stop NetworkManager

systemctl disable NetworkManager

setenforce 0

sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config

cat << e > /etc/sysconfig/network-scripts/ifcfg-ens33

TYPE=Ethernet

BOOTPROTO=static

NAME=ens33

DEVICE=ens33

ONBOOT=yes

IPADDR=$1

PREFIX=24

GATEWAY=192.168.115.2

DNS1=192.168.115.2

systemctl restart network

Put this script into the terminal, and then enter the IP you want to set to successfully configure the environment and set the ip

Results view

Second, the system resource script

1. Requirements

1. Write a script to monitor system resources such as CPU usage, memory usage, disk space, etc.
2. Display the usage of system resources in real time, and provide alarm function according to the preset threshold.
3. The script should be able to run in the background and automatically update the resource status at regular intervals.
4. Provide a simple user interface (command line or graphical interface), which is convenient for users to view the current system resources.

2. Script content

#! /bin/bash
#lsq
#Monitoring script
while true
do
times=10
#Disk
disk=$(df -Th | awk '{ print $6 }' | awk 'NR==6' |cut -d "%" -f 1 )
#Memory
mem=$(free -m | grep "Mem" | awk '{ printf "%.0f", $3/$2 * 100 }') #cpu cpu=$(top -n 1 | grep "Cpu
(
s )" | awk '{ printf "%.0f",

echo "Memory usage has reached $mem %, please note" && exit 0
fi
if [ $cpu -ge $cpu1 ];then
echo "CPU usage has reached $cpu %, please note" && exit 0
fi
if [ $disk - ge $disk1 ];then
echo "The disk usage has reached $disk, please pay attention" && exit 0
fi
sleep $times
done

3. Script analysis

This is a monitoring script to monitor the disk, memory and CPU usage of the system. The following is an analysis of each part of the script:

#!/bin/bash: Specifies that the script uses the Bash interpreter.
#mpy: Comment, used to explain the purpose of the script.
while true: An infinite loop, indicating that the script will continue to execute.
dotimes=10: Set the value of a variable dotimes to 10.
disk=$(df -Th | awk '{ print $6 }' | awk 'NR==6' |cut -d "%" -f 1): Use the df command to obtain disk information, and use the awk and cut commands to extract the numerical part of the disk usage.
mem=$(free -m | grep "Mem" | awk '{ printf "%.0f", $3/$2 * 100 }'): Use the free command to obtain memory information, and then use the awk command to calculate the percentage of memory usage.
cpu=$(top -n 1 | grep "Cpu(s)" | awk '{ printf "%.0f", $2+$4 }'): Use the top command to get CPU information, and use the awk command to calculate the percentage of CPU usage.
echo "******************": Print separator lines.
echo "CPU使用率$cpu %": Print CPU usage.
echo "内存使用率$mem %": Print memory usage.
echo "磁盘使用率$disk %": Print disk usage.
echo "******************": Print separator lines.
disk1=80: Set the value of a variable disk1 to 80, indicating the threshold of disk usage.
mem1=80: Set the value of a variable mem1 to 80, indicating the threshold of memory usage.
cpu1=80: Set the value of a variable cpu1 to 80, indicating the threshold of CPU usage.
if [ "$mem" -ge "$mem1" ]; then: If the memory usage is greater than or equal to the threshold mem1, execute the following command.
echo "内存使用已到$mem %,请注意" && exit 0: Print a warning message that the memory usage reaches the threshold and exit the script.
if [ $cpu -ge $cpu1 ]; then: If the CPU usage is greater than or equal to the threshold cpu1, execute the following command.
echo "CPU使用已到$cpu %,请注意" && exit 0: Print the warning message that the CPU usage reaches the threshold and exit the script.
if [ $disk -ge $disk1 ]; then: If the disk usage is greater than or equal to the threshold disk1, execute the following command.
echo "磁盘使用已到$disk ,请注意" && exit 0: Print a warning message that the disk usage reaches the threshold and exit the script.
sleep $times: Pause script execution for a period of time specified by the variable times.
done: End the while loop.

4. Empowerment and verification

3. Script to view the total size of the current memory, the actual size used, the remaining size, and the percentage of usage

1. The first method

#!/bin/bash

Mem_all=$(free -m | awk '/Mem/ {print $2}')
Mem_used=$(free -m | awk '/Mem/ {print $3}')
Mem_free=$(free -m | awk '/Mem/ {print $4}')
Mem_usage=$(free -m | awk '/Mem/ {printf "%.0f", $3/$2 * 100}')

echo "Total current memory: $Mem_all MB"
echo "Current memory used: $Mem_used MB"
echo "Current remaining: $Mem_free MB"
echo "Current physical memory usage: $Mem_usage%"

Two, verification

3. The second method

#!/bin/bash

# Get memory information
mem_info=$(free -m | awk 'NR==2{print}')

# Get total, used and remaining memory in megabytes
total=$(echo $mem_info | awk '{print $2}')
used=$(echo $mem_info | awk '{print $3} ')
free=$(echo $mem_info | awk '{print $4}')

# Calculate memory usage
usage_percent=$(echo "scale=2; $used / $total * 100" | bc)

# Print information
echo "Total physical memory: ${total}MB"
echo "Used memory: ${used}MB"
echo "Remaining memory: ${free}MB"
echo "Memory usage: ${usage_percent}% "

4. Verification

4. View the real-time traffic script of the network card

1. Edit script

#!/bin/bash
NIC=ens33
echo -e " In ------ Out"
while true; do
OLD_IN=$(awk '$0~"'$NIC'"{print $2}' /proc/net/dev)
OLD_OUT=$(awk '$0~"'$NIC'"{print $10}' /proc/net/dev)
sleep 1
NEW_IN=$(awk '$0~"'$NIC'"{print $2}' /proc/net/dev)
NEW_OUT=$(awk '$0~"'$NIC'"{print $10}' /proc/net/dev)
IN=$(printf "%.1f%s" "$((($NEW_IN-$OLD_IN)/1024))" "KB/s")
OUT=$(printf "%.1f%s" "$((($NEW_OUT-$OLD_OUT)/1024))" "KB/s")
echo "$IN $OUT"
sleep 1
done

2. Verification results

5. Change the suffix of all files with the suffix ".sh" in the current directory (including subdirectories) to ".shell", and then delete the second line of each file.

First look at the suffix files in the directory

1. Write a script

#!/bin/bash

ALL_SH_FILE=$(find . -type f -name "*.sh")

for file in ${ALL_SH_FILE[*]}

filename=$(echo $file | awk -F'.sh' '{print $1}')

new_filename="${filename}.shell"

mv "$file" "$new_filename"

sed -i '2d' "$new_filename"

done

Two, verification

6. Statistically visit the top ten IPs

1. First simulate the creation of IP and write scripts

vim /makeiplog.sh

#!/bin/bash
for i in {1..30};do
host=$[$RANDOM % 10]
host1=$[$RANDOM % 10]

echo "192.168.$host1.$host" >> /root/ip.log
done

Empower and activate

Second, verify the ip generation result

Enter vim ip.log to view

input the command

awk '{a[$1]++}END{print "UV:",length(a);for(v in a)print v,a[v]}' ip.log |sort -k2 -nr |head -10

Show results

awk '{a[$1]++}END{print "UV:",length(a);for(v in a)print v,a[v]}' ip.log |sort -k2

display in ascending order

7. Disk usage detection script

1. First lsblk to check the disk situation

echo fdisk.sh create

Second, enter the script

#!/bin/bash
# Intercept IP
IP=`ifconfig eth0 |awk -F " " 'NR==2{print $2}'`
# Define the usage rate and convert it to a number
SPACE=`df -Ph |awk '{ print int($5)}'`
for i in $SPACE
do
if [ $i -ge 80 ]
then
echo "The disk usage of $IP has exceeded 80%, please deal with it in time"
fi
done

Authorize and verify the result

If you change the script content to 90, it will prompt more than 90% during verification

./fdisk.sh verify

8. Back up the current date file

1. Write a script

#!/bin/bash
#一月前
historyTime=$(date "+%Y-%m-%d %H" -d '1 month ago')
echo ${historyTime}
historyTimeStamp=$(date -d "$historyTime" +%s)
echo ${historyTimeStamp}
#一周前
date_this_month=`date +%Y%m01`
#一天前
date_today=`date -d '1 day ago' +%Y%m%d`

It's a Bash script, and here's an explanation of each part:

historyTime=$(date "+%Y-%m-%d %H" -d '1 month ago'): Get the date and time one month ago and store it in a variable historyTime. dateThe options of the command -dare used to specify the date, "+%Y-%m-%d %H"indicating that the output format is year-month-day-hour.
echo ${historyTime}: Print historyTimethe value of the variable, which is the date and time one month ago.
historyTimeStamp=$(date -d "$historyTime" +%s): historyTimeConvert the variable into a timestamp format and store it in the variable historyTimeStamp. dateOptions to the command -dare used to specify a date, +%swhich represents the output timestamp.
echo ${historyTimeStamp}: Print historyTimeStampthe value of the variable, which is the timestamp one month ago.
date_this_month=date +%Y%m01``: Get the year and month of the current month, and add "01" at the end to indicate the first day of the current month. The result is stored in a variable date_this_month.
date_today=date -d '1 day ago' +%Y%m%d``: Get yesterday's date and store it in a variable in the format of year, month, and date_todayday .

The purpose of this script is to get the date and time before January and convert it into a timestamp format. Then, get the date of the first day of the month and yesterday's date.

2. Script result verification

root@localhost ~]# ./jiaoben.sh
2023-07-29 21
1690635600

Shell scripts are simple and commonly used (due to limited level, update from time to time!)

1. Shell script to configure the environment

Second, the system resource script

1. Requirements

2. Script content

3. Script analysis

4. Empowerment and verification

3. Script to view the total size of the current memory, the actual size used, the remaining size, and the percentage of usage

1. The first method

Two, verification

3. The second method

4. Verification

4. View the real-time traffic script of the network card

1. Edit script

2. Verification results

5. Change the suffix of all files with the suffix ".sh" in the current directory (including subdirectories) to ".shell", and then delete the second line of each file.

1. Write a script

Two, verification

6. Statistically visit the top ten IPs

1. First simulate the creation of IP and write scripts

Second, verify the ip generation result

7. Disk usage detection script

1. First lsblk to check the disk situation

Second, enter the script

8. Back up the current date file

1. Write a script

2. Script result verification

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