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lucapericlp/quick_remove.sh

Last active July 27, 2025 17:57
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  1. lucapericlp renamed this gist Jul 27, 2025. 1 changed file with 0 additions and 0 deletions.
    0 gistfile1.txt → quick_remove.sh
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  2. lucapericlp created this gist Jul 27, 2025.
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    #!/bin/bash

    # A script to terminate an EC2 instance and remove its local SSH config entry.

    # --- Configuration ---
    SSH_CONFIG_FILE="$HOME/.ssh/config"

    # Exit script if any command fails.
    set -e

    # --- 1. Get SSH Alias from Command Line ---
    if [ -z "$1" ]; then
    echo "❌ Error: No SSH alias provided."
    echo "Usage: $0 <ssh-alias>"
    exit 1
    fi

    SSH_ALIAS="$1"

    # --- 2. Find Instance ID from SSH Config ---
    echo "🔎 Searching for '$SSH_ALIAS' in $SSH_CONFIG_FILE..."

    # Find the line number of the "Host" directive for the given alias.
    # We use `head -n 1` to ensure we only act on the first match if there are duplicates.
    HOST_LINE_NUM=$(grep -n "Host $SSH_ALIAS" "$SSH_CONFIG_FILE" | head -n 1 | cut -d: -f1)

    if [ -z "$HOST_LINE_NUM" ]; then
    echo "❌ Error: Could not find an SSH entry for alias '$SSH_ALIAS' in $SSH_CONFIG_FILE."
    exit 1
    fi

    # The launch script places a comment with the Instance ID on the line directly above the "Host" line.
    COMMENT_LINE_NUM=$((HOST_LINE_NUM - 1))

    # Extract the Instance ID from that comment line using sed and awk.
    INSTANCE_ID=$(sed -n "${COMMENT_LINE_NUM}p" "$SSH_CONFIG_FILE" | awk '{print $6}')

    # Validate that we found a plausible instance ID.
    if [[ -z "$INSTANCE_ID" || ! "$INSTANCE_ID" =~ ^i- ]]; then
    echo "❌ Error: Could not parse a valid Instance ID for alias '$SSH_ALIAS'."
    echo "Please check the formatting in $SSH_CONFIG_FILE around line $HOST_LINE_NUM."
    exit 1
    fi

    echo "✅ Found Instance ID: $INSTANCE_ID"

    # --- 3. Confirm and Terminate Instance ---
    read -p "Are you sure you want to terminate instance $INSTANCE_ID? [y/N] " confirm
    # This regex checks for 'y' or 'Y'.
    if [[ ! "$confirm" =~ ^[yY] ]]; then
    echo "Termination cancelled."
    exit 0
    fi

    echo "🗑️ Terminating instance $INSTANCE_ID..."
    # Redirect stdout to /dev/null to keep the output clean.
    aws ec2 terminate-instances --instance-ids "$INSTANCE_ID" --output text > /dev/null

    echo "⏳ Waiting for instance to fully terminate..."
    aws ec2 wait instance-terminated --instance-ids "$INSTANCE_ID"
    echo "✅ Instance terminated."

    # --- 4. Clean up SSH Config ---
    echo "🧹 Cleaning up SSH config entry..."

    # The block created by the launch script is 10 lines total, plus a preceding blank line.
    # This makes it hard to remove robustly without line numbers.
    # The block starts with a blank line, then a comment, then the "Host" line.
    # So, the block to delete starts 2 lines *before* our HOST_LINE_NUM.
    START_DELETE=$((HOST_LINE_NUM - 2))
    # The block ends 7 lines *after* our HOST_LINE_NUM.
    END_DELETE=$((HOST_LINE_NUM + 7))

    # Use sed to delete the line range. The `-i.bak` option creates a backup and
    # is compatible with both Linux (GNU) and macOS (BSD) versions of sed.
    sed -i.bak "${START_DELETE},${END_DELETE}d" "$SSH_CONFIG_FILE"

    echo "✅ SSH config entry removed. Original config saved to ${SSH_CONFIG_FILE}.bak"

    # --- 5. Final Output ---
    echo "--------------------------------------------------"
    echo "✅ Success! Instance '$INSTANCE_ID' has been terminated and config cleaned up."
    echo "--------------------------------------------------"