Linux_5/ Vim, Shell（上）

		适用情况
1	if	分支、多分支	if else fi
2	for	范围	for do done
3	while	条件	while true do exit 0 done
4	case	判断	case ) ;; );; *)   esac

 

 

1, 接收用户参数

#!/bin/bash
#test
echo "Name of this shell is $0"
echo "Num of pare is $#"
echo "They are $*"
echo "1: $1, 2: $2"

 

2, if else

#!/bin/bash
#ping
ping -c 3 -i 0.2 -W 3 $1 &> /dev/null
if [ $? -eq 0 ]; then
        echo "Host $1 is on-line"
else
        echo "Host $1 is off-line"
fi

3, if elif else

#!/bin/bash
read -p "Enter the cord you get: " GRADE
if [ $GRADE -gt 85 ] && [ $GRADE -le 100 ]; then
        echo "$GRADE is Perfect"
elif [ $GRADE -gt 70 ] && [ $GRADE -le 85 ]; then
        echo "$GRADE is Good"
else
        echo "$GRADE is Failed"
fi

4

4.1, for

#!/bin/bash
#for
read -p "Enter the password for new users: " PW
for UN in `cat /root/user.txt`
do
        id $UN &> /dev/null
        #
        if [ $? -eq 0 ]; then
                echo
                echo "User $UN exists"
                echo
        else
                useradd $UN
                echo
                echo "$PW" | passwd --stdin $UN
                echo
                #
                id $UN &> /dev/null
                if [ $? -eq 0 ]; then
                        echo
                        echo "User $UN is created"
                        echo
                else
                        echo
                        echo "User $UN is not created"
                        echo
                fi
                #
        fi
        #
done

4.2, for

#!/bin/bash
#for
for UN in $(cat /root/user.txt)
do
        id $UN &> /dev/null
        #
        if [ $? -eq 0 ]; then
                userdel -r $UN
        else
                echo "User $UN does not exist"

        fi
        #
done

4.3 for

#!/bin/bash
#for
for HN in `cat /root/ip.txt`
do
        ping -c 3 -i 0.2 -W 5 $HN &> /dev/null
        #
        if [ $? -eq 0 ]; then
                echo "Host $HN is on-line"
        else
                echo "Host $HN is off-line"

        fi
        #

done

 

5, while

#!/bin/bash
#while
PRC=$(expr $RANDOM % 1000 )
TMS=0

while true
do
        read -p "Enter the price you guess: " GUS
        let TMS++
        #
        if [ $GUS -eq $PRC ]; then
                echo
                echo "Congradulations! The real price is $PRC, you tried $TMS times"
                echo
                exit 0
        elif [ $GUS -lt $PRC ]; then
                echo
                echo "LOW"
                echo
        else
                echo
                echo "HIGH"
                echo
        fi
        #

done

 

6, case