Termux script for luhn algorithim
To implement the Luhn algorithm in a Termux environment, you can use a simple shell script (e.g., in Bash). The Luhn algorithm is used to validate a variety of identification numbers, such as credit card numbers.
Here's how to create a script in Termux that validates a number using the Luhn algorithm:
1. **Open Termux.**
2. **Create a new script file** using a text editor like `nano` or `vi`. For example, using `nano`:
```bash
nano luhn.sh
```
3. **Paste the following script** into the text editor:
```bash
#!/data/data/com.termux/files/usr/bin/bash
# Function to validate using the Luhn algorithm
luhn_check() {
local number="$1"
# Remove all non-digit characters
number=$(echo "$number" | tr -cd '0-9')
# Start from the rightmost digit
local sum=0
local n_digits=${#number}
for (( i=0; i<n_digits; i++ )); do
digit="${number:n_digits-i-1:1}"
if (( i % 2 == 1 )); then
# Double the digit
(( digit *= 2 ))
if (( digit > 9 )); then
(( digit -= 9 ))
fi
fi
(( sum += digit ))
done
# Check if the total modulo 10 is zero
if (( sum % 10 == 0 )); then
echo "Valid number"
else
echo "Invalid number"
fi
}
# Check if an argument is provided
if [ $# -ne 1 ]; then
echo "Usage: $0 <number>"
exit 1
fi
luhn_check "$1"
```
4. **Save the file** and exit the editor (for `nano`, you can do this by pressing `CTRL + X`, then `Y`, and `ENTER`).
5. **Make the script executable**:
```bash
chmod +x luhn.sh
```
6. **Run the script** by providing a number to validate:
```bash
./luhn.sh <number>
```
Replace `<number>` with the actual number you want to check.
### Example Usage
```bash
./luhn.sh 79927398713
```
You should see output indicating whether the number is valid or invalid based on the Luhn algorithm.
### Notes
- Make sure you have `bash` installed in your Termux environment. It's usually included by default.
- The script removes any non-digit characters to ensure that it only processes numbers.
- Modify the script as needed for any extra functionality or error handling according to your preferences.
Update (2025-07-31):
You can create a simple shell script in Termux to implement the Luhn algorithm, which is a straightforward checksum formula used to validate various identification numbers, such as credit card numbers. Below is how you can set up this script in Termux.
### Steps to Create the Luhn Algorithm Script
1. **Open Termux** on your Android device.
2. **Create a new shell script file**. You can use any text editor; here we will use `nano`:
```bash
nano luhn.sh
```
3. **Copy and paste the following script into the file**:
```bash
#!/bin/bash
# Function to implement the Luhn algorithm
luhn() {
local number=$1
local sum=0
local alternate=0
# Process the number from right to left
for (( i=${#number}-1; i>=0; i-- )); do
local digit=${number:$i:1}
if [[ $alternate -eq 1 ]]; then
digit=$((digit * 2))
if [[ $digit -gt 9 ]]; then
digit=$((digit - 9))
fi
fi
sum=$((sum + digit))
alternate=$((1 - alternate)) # Toggle alternate
done
# Check if the sum is a multiple of 10
if (( sum % 10 == 0 )); then
echo "Valid"
else
echo "Invalid"
fi
}
# Check if the user has provided an argument
if [[ $# -ne 1 ]]; then
echo "Usage: $0 "
exit 1
fi
# Call the luhn function with the input number
luhn "$1"
```
4. **Save the file and exit**. If you are using `nano`, press `CTRL + X`, then `Y`, and then `ENTER`.
5. **Make the script executable**:
```bash
chmod +x luhn.sh
```
6. **Run the script with a number to check its validity**:
```bash
./luhn.sh 4532015112830366
```
### Example
If you run the script with a valid number like `4532015112830366`, it should return `Valid`. If you use an invalid number, it will return `Invalid`.
### Note
Make sure to replace `4532015112830366` with the number you want to check. The script checks the provided number against the Luhn checksum and prints whether it's valid or not.
This script is a simple implementation and can be modified or extended based on your needs.
Update (2025-07-31):
Sure! The Luhn algorithm (also known as the modulus 10 algorithm) is used to validate various identification numbers, such as credit card numbers. You can run scripts in Termux in languages such as Python. Below is a simple Python script that implements the Luhn algorithm.
### Steps to Use
1. **Install Python**: If you haven't already installed Python on Termux, you can do so by running:
```bash
pkg install python
```
2. **Create the script**: You can create a new Python file using a text editor like `nano`. For example:
```bash
nano luhn.py
```
3. **Add the Luhn algorithm code**: Copy and paste the following code into the `luhn.py` file.
```python
def luhn_check(card_number):
# Reverse the card number and convert to a list of integers
digits = [int(d) for d in str(card_number)[::-1]]
# Double every second digit from the right
for i in range(1, len(digits), 2):
digits[i] *= 2
# If doubling results in a number > 9, subtract 9
if digits[i] > 9:
digits[i] -= 9
# Calculate the sum of all digits
total = sum(digits)
# Valid if total modulo 10 is 0
return total % 10 == 0
# Main function to test the Luhn algorithm
if __name__ == "__main__":
card_number = input("Enter the card number: ")
if luhn_check(card_number):
print("The card number is valid.")
else:
print("The card number is invalid.")
```
4. **Save and exit**: In `nano`, you can save and exit by pressing `CTRL + X`, then press `Y` to confirm saving, and hit `Enter`.
5. **Run the script**: You can now run the script using Python:
```bash
python luhn.py
```
6. **Input the Card Number**: When prompted, enter the card number you want to validate.
### Example Usage
```plaintext
Enter the card number: 4532015112830366
The card number is valid.
```
This script checks if the given credit card number is valid according to the Luhn algorithm, and it will inform you whether it's valid or not.