if条件测试语句

1.vim mkcdrom.sh
2.#!/bin/bash
DIR="/media/cdrom"
if [ ! -e $DIR ]
then
mkdir -p $DIR
fi
3.
4.vim chkhost.sh
5.#!/bin/bash
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
6.
7.vim chkscore.sh
8.#!/bin/bash
read -p "Enter your score（0-100）：" GRADE
if [ $GRADE -ge 85 ] && [ $GRADE -le 100 ] ; then
echo "$GRADE is Excellent"
elif [ $GRADE -ge 70 ] && [ $GRADE -le 84 ] ; then
echo "$GRADE is Pass"
else
echo "$GRADE is Fail"
fi
9.