COM584 Class Test #1 Week #3 Notes - created from Mind Map

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File Permissions

Shell Scripts

Exit Status Codes

- Sent to the shell when a program or command is quite.

Notations

Symbolic: Uses criteria such as categories and operators to change file permissions.

Example: chmod u+x file4

Numeric: Uses numbers from 0-7 to represent file permissions.

Example: chmod 774 file4

Compiler: A program that translate source code into executable program.

Interpreters: Accepts and parses instruction, the converts into executable instructions, then executes.

Variables

Environment: A placeholder for data that can change - gets its value automatically from the OS startup or shell being used.

E.G Home / Path

Shell: A placeholder for data that can change - value is assigned in a shell script.

Direct Assignment: Specify the variable's value in the command. Value outputted via echo command.

echo $var Fearghal

Prompt Method: User is asked to enter a value for the variable.

Positional Parameters: Parameter passed as argument to command.

Successful Commands: Exit Status Code = 0

Failed Commands: Exit Status Code > 0