Very practical shell and shellcheck

shell Scripting is a powerful tool to help programmers and system administrators complete the tedious work that takes time and effort , It is an effective way to interact with computers and manage files and system operations . Just a few lines of code , You can get the computer close to doing what you want .

Kill all scripts

#!/bin/bash
################################################################
# There are some scripts added to cron In , There are situations where the script has not finished running yet and new tasks need to be executed ,
# Causes the system load to rise , So you can write a script , Select the processes that affect the load and kill them all at once .
################################################################
ps aux|grep  Specify the process name |grep -v grep|awk '{print $2}'|xargs kill -9

from FTP Server downloads files

#!/bin/bash
if [ $# -ne 1 ]; then
    echo "Usage: $0 filename"
fi
dir=$(dirname $1)
file=$(basename $1)
ftp -n -v << EOF   # -n  automatic logon 
open 192.168.1.10  # ftp The server 
user admin password
binary   #  Set up ftp The transmission mode is binary , avoid MD5 Value is different or .tar.gz Compressed package format error 
cd $dir
get "$file"
EOF

Batch modify file name

 Example ：

# touch article_{1..3}.html
# ls
article_1.html  article_2.html  article_3.html
 Purpose ： hold article Change it to bbs

 Method 1：

for file in $(ls *html); do
    mv $file bbs_${
    file#*_}
    # mv $file $(echo $file |sed -r 's/.*(_.*)/bbs\1/')
    # mv $file $(echo $file |echo bbs_$(cut -d_ -f2)
done
 Method 2：

for file in $(find . -maxdepth 1 -name "*html"); do
     mv $file bbs_${
    file#*_}
done
 Method 3：

# rename article bbs *.html

Scan host port status

#!/bin/bash
HOST=$1
PORT="22 25 80 8080"
for PORT in $PORT; do
    if echo &>/dev/null > /dev/tcp/$HOST/$PORT; then
        echo "$PORT open"
    else
        echo "$PORT close"
    fi
done

Judge whether the user input is IP Address

 Method 1:

#!/bin/bash
function check_ip(){
    
    IP=$1
    VALID_CHECK=$(echo $IP|awk -F. '$1< =255&&$2<=255&&$3<=255&&$4<=255{print "yes"}')
    if echo $IP|grep -E "^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$">/dev/null; then
        if [ $VALID_CHECK == "yes" ]; then
            echo "$IP available."
        else
            echo "$IP not available!"
        fi
    else
        echo "Format error!"
    fi
}
check_ip 192.168.1.1
check_ip 256.1.1.1
 Method 2：

#!/bin/bash
function check_ip(){
    
    IP=$1
    if [[ $IP =~ ^[0-9]{
    1,3}\.[0-9]{
    1,3}\.[0-9]{
    1,3}\.[0-9]{
    1,3}$ ]]; then
        FIELD1=$(echo $IP|cut -d. -f1)
        FIELD2=$(echo $IP|cut -d. -f2)
        FIELD3=$(echo $IP|cut -d. -f3)
        FIELD4=$(echo $IP|cut -d. -f4)
        if [ $FIELD1 -le 255 -a $FIELD2 -le 255 -a $FIELD3 -le 255 -a $FIELD4 -le 255 ]; then
            echo "$IP available."
        else
            echo "$IP not available!"
        fi
    else
        echo "Format error!"
    fi
}
check_ip 192.168.1.1
check_ip 256.1.1.1
 Added version ：

 Add a dead cycle , If IP Exit when available , Do not use the prompt to continue , And use awk Judge .

#!/bin/bash
function check_ip(){
    
    local IP=$1
    VALID_CHECK=$(echo $IP|awk -F. '$1< =255&&$2<=255&&$3<=255&&$4<=255{print "yes"}')
    if echo $IP|grep -E "^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$" >/dev/null; then
        if [ $VALID_CHECK == "yes" ]; then
            return 0
        else
            echo "$IP not available!"
            return 1
        fi
    else
        echo "Format error! Please input again."
        return 1
    fi
}
while true; do
    read -p "Please enter IP: " IP
    check_ip $IP
    [ $? -eq 0 ] && break || continue
done

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