Bash Shell Scripting Basics

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Questions and Answers

What is the purpose of the ${10}, ${11} syntax in shell scripting?

To represent the exit code of the last command

To access the command-line arguments beyond the ninth (correct)

To represent all command-line arguments as a single string

To access the script name and shell name

Which special parameter holds the name of the script or shell itself?

$0 (correct)

What is the purpose of the $@ special parameter in shell scripting?

To represent the exit code of the last command

To represent all command-line arguments as separate strings (correct)

To hold the name of the script or shell itself

To access the command-line arguments beyond the ninth

How do you access the second command-line argument in a shell script?

Using the $2 variable Signup and view all the answers

What is the purpose of the $# special parameter in shell scripting?

To represent the number of command-line arguments Signup and view all the answers

What is the purpose of the $? special parameter in shell scripting?

To represent the exit code of the last command Signup and view all the answers

What is the purpose of the `typeset` command in shell scripting?

To define or change the properties of a variable Signup and view all the answers

What is the purpose of the `$*` special parameter in shell scripting?

To get all arguments as a single string Signup and view all the answers

What is the purpose of the `unset` command in shell scripting?

To delete a variable Signup and view all the answers

What is stored in the `$0` positional parameter in shell scripting?

The name of the script itself Signup and view all the answers

What is the purpose of the `export` command in shell scripting?

To export a variable to the environment Signup and view all the answers

What is the purpose of the `read` command in shell scripting?

To read input from the user and store it in a variable Signup and view all the answers

What is the purpose of the `$#` special parameter in a bash script?

To store the number of arguments Signup and view all the answers

What is the purpose of the `$@` special parameter in a bash script?

To store all command-line arguments as a list Signup and view all the answers

How can you check the exit status of the last command in a bash script?

Using the <code>$?</code> variable Signup and view all the answers

What is the purpose of the `-v` option in a bash script?

To specify the verbosity level of the script Signup and view all the answers

What is the default exit status used by the `exit` command if no argument is provided?

The exit status of the last command Signup and view all the answers

What is the range of exit statuses in a bash script?

0-255 Signup and view all the answers

Study Notes

Positional Parameters

Positional parameters are used to access arguments passed to a shell script
The first nine arguments can be accessed using $1, $2, ..., $9
Arguments beyond the ninth can be accessed using ${10}, ${11}, and so on

Special Parameters

Special parameters are predefined variables that hold special meanings and values in a script
$0: holds the name of the script or shell itself
$1, $2, $3...: represent the command-line arguments passed to the script
$#: represents the number of command-line arguments passed to the script
$*: represents all the command-line arguments passed to the script as a single string
$@: represents all the command-line arguments passed to the script as separate strings
$?: holds the exit code of the last command executed in the script

Command Line Arguments

Command line arguments refer to the values passed to a shell script or program when it is executed in the command line
Command line arguments are stored in special variables called positional parameters
The first argument is stored in $1, the second argument in $2, and so on
$0 stores the name of the script or program itself

Control Flow and Conditional Statements

The if statement is used to check conditions and execute commands based on the outcome
The -n option is used to check if a string is not null
The == operator is used to check for string equality

Exit and Exit Status of a Command

Every command that is executed returns an exit status
The exit status is an integer value that indicates whether the command has executed successfully or encountered an error
The exit status can be checked using the $? variable in the shell
The exit status ranges from 0 to 255, with 0 indicating successful execution and any non-zero value indicating an error
The exit command is used to terminate the execution of a shell script or a command

Variable Commands

read command: used to read input from the user and store it in a variable
export command: used to export a variable to the environment
typeset command: used to define or change the properties of a variable
unset command: used to delete a variable

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Description

Learn about accessing arguments in bash shell scripts. Understand how to use positional parameters and their syntax in shell scripting. Test your knowledge with this quiz!