Let’s break down what this script does in detail. The script is named mvg.sh, authored by GJS (homelab-alpha), and its purpose is to create a function called mvg that moves a file or directory to a specified destination and then enters the destination directory. The script also ensures the source and destination are valid and provides functionality to add metadata to itself if it’s missing.

Here’s a detailed explanation:

Script Metadata

  • Filename: mvg.sh
  • Author: GJS (homelab-alpha)
  • Date: May 26, 2024
  • Version: 1.0.1
  • Description: This script moves a file or directory to a specified destination and then enters the destination directory.
  • RAW Script: mvg.sh

Function: mvg

The function mvg is the core of the script. Here’s a step-by-step breakdown of what it does:


Argument Check 

if [ $# -ne 2 ]; then
  echo "Usage: mvg source destination"
  return 1
fi

The script first checks if the number of arguments provided is exactly two (the source and the destination). If not, it prints a usage message and exits the function with a status of 1.


Variable Assignment 

local source="$1"
local destination="$2"

The script assigns the first argument to source and the second argument to destination.


Source Existence Check 

if [ ! -e "$source" ]; then
  echo "Source does not exist: $source"
  return 1
fi

It checks if the source exists using the -e flag. If the source doesn’t exist, it prints an error message and exits the function with a status of 1.


Destination Validity Check 

if [ ! -d "$destination" ]; then
  echo "Destination is not a directory: $destination"
  return 1
fi

It checks if the destination exists and is a directory using the -d flag. If the destination is not a directory, it prints an error message and exits the function with a status of 1.


Move and Enter Directory 

mv "$source" "$destination" && cd "$destination/$(basename "$source")" || exit

If both checks pass, the script moves the source to the destination using the mv command. Then, it tries to change the directory to the new location of the moved source using cd. If either of these commands fails, it exits the script.


Script Metadata Management

The script also includes functionality to add metadata descriptions and usage examples if they are missing from the script.

Add Description 

description=$(grep -c "# Description:" "$0")
if [ "$description" -eq 0 ]; then
  sed -i '2i# Description: This script moves a file or directory to a specified destination and then enters the destination directory.' "$0"
fi

It checks if the description line is present in the script using grep. If not, it inserts the description after the second line using sed.


Add Usage Example 

usage_example=$(grep -c "# Example usage:" "$0")
if [ "$usage_example" -eq 0 ]; then
  sed -i '4i# Example usage: ./mvg.sh source_file.txt destination_directory/' "$0"
fi

It checks if the usage example line is present in the script using grep. If not, it inserts the usage example after the fourth line using sed.


Conclusion

This script is a useful tool for moving files or directories to a new location and ensuring the working directory is updated to the new location, while also maintaining its own documentation.

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Last updated 01 Sep 2024, 10:22 CEST . history