shell script equals sign

What line of output does shell script determine if a string is equal to 3 or 99?

You can use if-elif-else syntax to write multiple conditional statements.

1, first of all, to understand the basic usage of if-else, if condition + then operation + else operation + fi closure, written as follows:

2, if-elif-else syntax of the specific format – if single-conditional multi-branching, written as follows:

3, Example – if single-conditional multi-branching, the output of this example is: a is less than b.

4. Example-if multi-conditional multi-branching, the output of this example is: a is equal to b,or a is less than 10.

Please teach shell script variable how to equal more than one value

1, linuxshell in the general definition of the variable format: var = value. where var is the name of the variable, = is the assignment, value is the value assigned to the variable. For example, the following variable definition.

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a=12;

b=”helloworld”

2. Note that the first character of a variable name cannot be a number, but it can be an underscore. The following example is an illegal variable name.

3. To use the value of a variable, put a $ sign in front of the variable. For example, the following example:

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123=123/// This is the wrong variable name

_123=123/// This is legal.

Shell Programming (Quick Start and Hands-On Tips)

Shell programming is a way of writing scripts that allow the user to execute a series of commands from the command line.A shell is a command line interpreter that interprets commands entered by the user and translates them into a language that the computer understands.Shell programming is a script programming language that uses Shell scripts to write programs.

Why Learn Shell Programming

Shell programming is a very useful skill that can help you automate tasks on a Unix or Linux system.Shell programming allows you to write simple scripts to perform repetitive tasks, which can save a great deal of time and effort.Shell programming also allows you to write efficient scripts to work with data and files, which can be very useful for data analysis and processing.

Basics of Shell Programming

The basics of Shell programming include the Shell scripting language, variables, conditional statements, looping statements, functions, and arrays.

Shell Scripting Language

The Shell Scripting Language is an interpreted language that does not require a compiler, but is executed directly from the command line.Shell scripts usually end with a .sh extension, such as script.sh. The Shell Scripting Language has many commands and operators available to help you with a variety of tasks.

Variables

In Shell programming, variables are a way to store values. Variables can store various types of data, including numbers, strings, and arrays. In Shell programming, variables are often referenced using the $ symbol, such as $variable.The value of a variable can be set by an assignment statement, such as variable=”hello”.

Conditional Statements

Conditional statements are a way of executing different commands based on conditions. In Shell programming, conditional statements are usually implemented using the if-then-else construct. For example, if the variable x is equal to 1, the following code can be used:

if[$x-eq1]

then

echo “xisequalto1”

else

echo “xisnotequalto1”

fi

loop statement

A looping statement is a way of repeating a command. In Shell programming, loop statements are usually implemented using a for or while structure. For example, the following code will print the numbers 1 through 10:

foriin{1..10}

do

echo$i

done

Functions

Functions are a way of encapsulating a set of commands together. In Shell programming, functions are usually defined using a function name and a list of arguments. For example, the following code defines a function named hello:

hello(){

echo “Hello,$1!”

}

The function can be called using the following code:

hello “world”

array

An array is a way to store multiple values. In Shell programming, arrays are often defined and referenced using parentheses. For example, the following code defines an array called fruits:

fruits=(“apple” “banana” “orange”)

The elements of this array can be referenced using the following code:

echo${fruits[0]}犑 Blossom Carp Apple

Shell Programming Hands-On Tips

Besides the basics, here are some Shell programming hands-on tips that can help you get better at using Shell programming.

Command Line Parameters

Command Line Parameters are the parameters that are passed to a Shell script on the command line. In Shell programming, you can use variables such as $1, $2, etc. to refer to these parameters. For example, the following code will print the first parameter passed to the script:

echo$1

Redirection and piping

Redirection and piping are two ways to redirect the output of a command to a file or other command. In Shell programming, you can use the > and > > operators to redirect output to a file. For example, the following code will redirect the output of a command to a file:

ls>files.txt

Command substitution

Command substitution is a way to use the output of a command as a variable value. In Shell programming, command substitution can be implemented using the $() or “ operators. For example, the following code takes the output of a command as a variable value:

files=$(ls)

Error Handling

Error handling is a way of dealing with command execution errors. In Shell programming, you can use the set-e command to set a script to exit on an error. For example, the following code would set a script to exit on an error:

set-e

Debugging

Debugging is a way of finding and fixing script errors. In Shell programming, you can use the set-x command to set a script to output the results of the execution of each command. For example, the following code would set the script to output the results of each command’s execution:

set-x