1.read读取方式：

[root@www scripts]# vim read_1.sh 
  #!/bin/bash
  # Filename: read_1.sh
  # Describe: Integer arithmetic
  # Author: Lijun
  # Date: 2015-08-24
  # Version: 1.0.1
   
  read -p "Please input two nums: " a b                  
   
  if [ -z $a ] || [ -z $b ]
  then
    echo "Please input two nums again."
    exit 1
  fi
   
  expr $a + 1 > /dev/null 2>&1
  RETVAL1=$?
  expr $b + 1 > /dev/null 2>&1
  RETVAL2=$?
   
  if [ $RETVAL1 -ne 0 ] || [ $RETVAL2 -ne 0 ]
  then
    echo "Please input two nums(must be integer)."
    exit 2
  else
    echo "a+b=$(( $a + $b ))"
    echo "a-b=$(( $a - $b ))"
    echo "a*b=$(( $a * $b ))"
    echo "a/b=$(( $a / $b ))"
    echo "a%b=$(( $a % $b ))"
    exit 0
  fi


2.脚本传参的方式：
[root@www scripts]# vim read_2.sh  
  #!/bin/bash                                   
  # Filename: read_2.sh                         
  # Describe: Integer arithmetic                
  # Author: Lijun                               
  # Date: 2015-08-24                            
  # Version: 1.0.2                              
                                            
  a=$1                                       
  b=$2                                       
  #判断参数个数                                   
  if [ $# -ne 2 ]                               
  then                                       
      echo "Usage: sh `basename $0` {NUM1 NUM2}"             
      exit 1                                  
  fi          
  #判断a,b是不是整数  
  expr $a + 1 > /dev/null 2>&1                  
  RETVAL1=$?                                    
  expr $b + 1 > /dev/null 2>&1                  
  RETVAL2=$?                                  
    
  if [ $RETVAL1 -ne 0 ] || [ $RETVAL2 -ne 0 ]   
  then                                       
    echo "Please input two integers(must be integer)."
    exit 2                                  
  else
    echo "a+b=$(( $a + $b ))"                 
    echo "a-b=$(( $a - $b ))"                 
    echo "a*b=$(( $a * $b ))"                 
    echo "a/b=$(( $a / $b ))"                 
    echo "a%b=$(( $a % $b ))"                 
    exit 0                                  
  fi

                                         

3. 

[root@www scripts]# vim read_3.sh 
  #!/bin/bash                                      
  # Filename: read_3.sh                            
  # Describe: Integer arithmetic                   
  # Author: Lijun                                
  # Date: 2015-08-24                               
  # Version: 1.0.3                                
                                           
  read -p "Please input two nums: " a b            
                                           
  if [ -z $a ] || [ -z $b ]                        
  then                                       
    echo "Please input two nums again."          
    exit 1                                  
  fi                                        
  #整数判断的另一种方法                              
 echo $a |egrep -o "[^0-9]{1,}" > /dev/null || echo $b |egrep -o "[^0-9]{1,}" > /dev/null &&\
  echo "Please input two nums(must be integer)."|| {             
  echo "a+b=$(( $a + $b  ))"                       
  echo "a-b=$(( $a - $b  ))"                       
  echo "a*b=$(( $a * $b  ))"                       
  echo "a/b=$(( $a / $b  ))"                       
  echo "a%b=$(( $a % $b  ))"                       
  }
4.
[root@oldjun-study scripts]# vim read_4.sh 
#!/bin/bash
# Filename: read_4.sh                            
# Describe: Integer arithmetic                   
# Author: Lijun                                
# Date: 2015-08-26                               
# Version: 1.0.4  
      
read -p "pls input two nums: " a b

#通过字符串的长度，来判断参数的个数（变量为空或没声明，值为0，即参数个数为0）
if [ ${#a} -eq 0 ] || [ ${#b} -eq 0 ]
then 
    echo "a or b is null,pls input two nums again!"
    exit 1
fi
expr $a + 1 > /dev/null 2>&1
RETVAL1=$?
expr $b + 1 > /dev/null 2>&1
RETVAL2=$?
if [ $RETVAL1 -ne 0  ] || [ $RETVAL2 -ne 0  ]
then
    echo "Please input two nums(must be integer)."
    exit 2
else
    echo "a+b=$(( $a + $b  ))"
    echo "a-b=$(( $a - $b  ))"
    echo "a*b=$(( $a * $b  ))"
    echo "a/b=$(( $a / $b  ))"
    echo "a%b=$(( $a % $b  ))"
    exit 0
fi