Function handle_list_command 

pub fn handle_list_command(
    source: Option<&str>,
    query: Option<&str>,
    format: &str,
    sort: &str,
    names_only: bool,
    limit: Option<usize>,
    stats: bool,
) -> Result<()>

Handles the list command to display environment variables with various formatting options.

Arguments

• source - Optional filter by source (system, user, process, shell)
• query - Optional search query to filter variables
• format - Output format (table, json, simple, compact)
• sort - Sort order (name, value, source)
• names_only - Whether to display only variable names
• limit - Optional limit on number of variables to display
• stats - Whether to display statistics

Errors

Returns an error if:

• Environment variables cannot be loaded
• Invalid source type is provided
• JSON serialization fails