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Setting Environment Variables in Linux Linux offers two approaches for configuring environment variables: temporary and permanent. Temporary Configuration Variables set this way disappear when the terminal closes. Use the export command directly: export APP_VAR="Hello World" export PATH=$PATH:/opt/myapp/bin Alternatively, assign firs ...

Terminal Interaction and Directory Navigation Adjusting the terminal font size can be done quickly using Ctrl + Shift + +. To toggle between the current working directory and the previous one, use cd -. For instance, if you navigate from /var/log to /etc/nginx using cd /etc/nginx, running cd - will instantly return you to /var/log. Executing it ...

Shell Functions Defining Functions Functions in shell scripts encapsulate reusable blocks of code. There are two common syntax styles: # Style 1: Using the function keyword function my_function { commands } # Style 2: Bash-compatible parentheses syntax my_function() { commands } Inspecting Defined Functions The declare builtin provide ...

The Shell acts as the interface between the Linux kernel and the user, serving as the primary mechanism for system management and communication. Depending on the initialization method, a Shell session operates in one of four distinct modes, defined by two criteria: authentication status (Login or Non-login) and interactivity (Interactive or Non ...

Effective system administration relies on robust monitoring scripts. This guide explores best practices for implementing service health checks and automated recovery using Bash conditional logic. 1. System Resource Monitoring To monitor system memory and alert administartors, we can leverage the free utility. The following script checks if avai ...

Most community-contributed GMT plotting scripts are written as Linux bash scripts, which can be challenging for Windows users unfamiliar with bash syntax. This guide explains how to adapt bash scripts for use on Windows by converting them to batch (.bat) files. The core differences between bash and batch scripts are straightforward: Comments: ...

Positional Parameters Positional parameters allow scripts to accept command-line arguments: $0 - Name of the currently executing script $n - nth argument passed to the script (use braces for n > 10, e.g., ${10}) $# - Number of arguments passed to the script $* - All arguments as a single string $@ - All arguments as separate string ...

Conditional Expression Syntax Bash supports four syntax forms for condition testing: Syntax Description test expression Uses the test command [ expression ] Single brackets, functionally identical to test [[ expression ]] Double brackets, enhanced version of the above ((expression)) Double parentheses, typically used with if statem ...

Arithmetic Operations Script files must begin with #!/bin/bash. Comment are denoted by #. Code should be properly indented with whitespace. Arithmetic operations support: +, -, *, /, **, %. Evaluation methods: # Method 1 let VAR=arithmetic-expression # Method 2 VAR=$[arithmetic-expression] # Method 3 VAR=$((arithmetic-expression)) # Method 4 ...

Script Structure and Execution Shell scripts require a shebang line at the beginning to specify the interpreter: #!/bin/bash #!/usr/bin/python3 Comments use the # symbol and are single-line only. To execute a script: chmod +x script.sh ./script.sh Input and Output Reading input with read: read input_var read -p "Enter value: " pro ...