清单6-2。valint,检查有效整数 valint() #@ USAGE: valint INTEGER case ${1#-} in ## Leading hyphen removed to accept negative numbers *[!0-9]*) false;; ## the string contains a non-digit character *) true ;; ## the whole number, and nothing but the number esac 如果函数体用括...
After you run the function test cases, then you could restore the server from the backup, and you would be ready for the next round of testing. 6. Check for input parameters and environment variables It is a good idea to validate the input parameters and to check if the necessary environm...
可以使用read命令来实现。read命令用于从标准输入读取用户输入的值,并将其赋给一个变量。 具体用法如下: ``` read variable_name ``` 其中,variable_name是...
The += operator allows you to add or append the righthand side of the assignment to an existing value. Integer variables treat the righthand side as an expression, which is evaluated and added to the value. Arrays add the new elements to the array. For example: $ name=Arnold $ name+=...
intvar=123 # Assigning integer value. echo $intvar intvar=12.3 #Trying to store string type value to an integer variable echo $intvar declare -r rovar=281 rovar=212 # Trying to change the readonly variable. From the below execution, you can notice the error message when you assign inval...
Variables SET by the shell and variables USED by the shellThe following variables are set by the shell: BASH Expands to the full file name used to invoke this instance of bash. BASH_ARGC An array variable whose values are the number of parameters in each frame of the current bash ...
Used as an input parameter that you can add when running script. exit [0-255] Used to exit the script and return the number from 0 to 255. $ Used for parameters and variables. () Used for running commands in a subshell. $() Used to save the output of commands. (()) Used ...
Two integer values will be taken from the user and printed the result of addition. #!/bin/bash echo "Enter first number" read x echo "Enter second number" read y (( sum=x+y )) echo "The result of addition=$sum" Run the file with bash command. $ bash add_numbers.sh You can ...
/Integer division (without decimal) %Modulus division (only remainder) **Exponentiation (a to the power b) Here's an example of performing summation and subtraction in bash script: #!/bin/bash read -p "Enter first number: " num1 read -p "Enter second number: " num2 sum=$(($num1+...
Declare local variables 'num1' and 'num2' to store the arguments passed to the function. Calculate the sum of 'num1' and 'num2' and store it in the 'sum' variable. Use echo to output the value of sum. Finally test the "add()" function by calling it with two numbers and storing...