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Questions and Answers
What is the purpose of the ${10}, ${11} syntax in shell scripting?
Which special parameter holds the name of the script or shell itself?
What is the purpose of the $@ special parameter in shell scripting?
How do you access the second command-line argument in a shell script?
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What is the purpose of the $# special parameter in shell scripting?
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What is the purpose of the $? special parameter in shell scripting?
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What is the purpose of the typeset
command in shell scripting?
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What is the purpose of the $*
special parameter in shell scripting?
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What is the purpose of the unset
command in shell scripting?
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What is stored in the $0
positional parameter in shell scripting?
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What is the purpose of the export
command in shell scripting?
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What is the purpose of the read
command in shell scripting?
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What is the purpose of the $#
special parameter in a bash script?
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What is the purpose of the $@
special parameter in a bash script?
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How can you check the exit status of the last command in a bash script?
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What is the purpose of the -v
option in a bash script?
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What is the default exit status used by the exit
command if no argument is provided?
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What is the range of exit statuses in a bash script?
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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!