since you are using XAMPP PHP located at /opt/lampp/bin/php (version 8.2.12), you must build, install, and enable the GMP extension for this exact PHP version.
Follow these steps carefully.

ONE-COMMAND GMP INSTALL (XAMPP PHP 8.2.12)

sudo apt update && \
sudo apt install -y build-essential autoconf automake libtool pkg-config libgmp-dev re2c bison wget && \
cd /tmp && \
wget -q https://www.php.net/distributions/php-8.2.12.tar.gz && \
tar -xzf php-8.2.12.tar.gz && \
cd php-8.2.12/ext/gmp && \
/opt/lampp/bin/phpize && \
./configure --with-php-config=/opt/lampp/bin/php-config && \
make -j"$(nproc)" && \
sudo make install && \
grep -q '^extension=gmp.so' /opt/lampp/etc/php.ini || echo 'extension=gmp.so' | sudo tee -a /opt/lampp/etc/php.ini && \
sudo /opt/lampp/lampp restart && \
/opt/lampp/bin/php -m | grep -i gmp && \
/opt/lampp/bin/php -r 'echo function_exists("gmp_init") ? "GMP OK\n" : "GMP NOT OK\n";'

Step 0: Check your XAMPP PHP version

Run this command to confirm the PHP version you are using:

/opt/lampp/bin/php -v

You should see PHP 8.2.12.

Step 1: Install required build packages (Ubuntu/Debian)

These packages are required to compile the GMP extension.

sudo apt update
sudo apt install -y build-essential autoconf automake libtool pkg-config libgmp-dev re2c bison

⚠️ Important:
libgmp-dev is mandatory. Without it, GMP will not compile.

Step 2: Download PHP source code (same version: 8.2.12)

cd /tmp
wget https://www.php.net/distributions/php-8.2.12.tar.gz
tar -xzf php-8.2.12.tar.gz

This gives you the PHP source files needed to compile extensions.

Step 3: Compile GMP extension using XAMPP PHP

Go to the GMP extension directory:

cd /tmp/php-8.2.12/ext/gmp

Now run these commands using XAMPP’s phpize and php-config:

/opt/lampp/bin/phpize
./configure --with-php-config=/opt/lampp/bin/php-config
make -j"$(nproc)"
sudo make install

✅ After this, the file gmp.so will be installed in XAMPP’s PHP extension directory.

Step 4: Confirm gmp.so is installed

Run:

EXT_DIR=$(/opt/lampp/bin/php -r 'echo ini_get("extension_dir");')
echo "EXT_DIR=$EXT_DIR"
ls -l "$EXT_DIR" | grep -i gmp

Expected result:
You should see gmp.so listed.

Step 5: Enable GMP in XAMPP php.ini

Open the XAMPP PHP configuration file:

/opt/lampp/etc/php.ini

Edit it:

sudo vi /opt/lampp/etc/php.ini

Search for GMP:

• Press /gmp and hit Enter

Make sure this line exists exactly like this:

extension=gmp.so

⚠️ If you see:

extension=gmp

Change it to:

extension=gmp.so

Save and exit:

• Type :wq and press Enter

Step 6: Restart XAMPP

sudo /opt/lampp/lampp restart

Step 7: Verify GMP is enabled

Check loaded PHP modules:

/opt/lampp/bin/php -m | grep -i gmp

Expected output:

gmp

Extra check:

/opt/lampp/bin/php -r 'echo function_exists("gmp_init") ? "GMP OK\n" : "GMP NOT OK\n";'

Expected output:

GMP OK

If you get an error in Step 3

Run these commands and share the error output:

/opt/lampp/bin/phpize -v
/opt/lampp/bin/php-config --version

Also copy and paste any error messages from:

• ./configure
• make

ONE-COMMAND GMP INSTALL (XAMPP PHP 8.2.12)

sudo apt update && \
sudo apt install -y build-essential autoconf automake libtool pkg-config libgmp-dev re2c bison wget && \
cd /tmp && \
wget -q https://www.php.net/distributions/php-8.2.12.tar.gz && \
tar -xzf php-8.2.12.tar.gz && \
cd php-8.2.12/ext/gmp && \
/opt/lampp/bin/phpize && \
./configure --with-php-config=/opt/lampp/bin/php-config && \
make -j"$(nproc)" && \
sudo make install && \
grep -q '^extension=gmp.so' /opt/lampp/etc/php.ini || echo 'extension=gmp.so' | sudo tee -a /opt/lampp/etc/php.ini && \
sudo /opt/lampp/lampp restart && \
/opt/lampp/bin/php -m | grep -i gmp && \
/opt/lampp/bin/php -r 'echo function_exists("gmp_init") ? "GMP OK\n" : "GMP NOT OK\n";'

Abhishek Singh

I’m Abhishek, a DevOps, SRE, DevSecOps, and Cloud expert with a passion for sharing knowledge and real-world experiences. I’ve had the opportunity to work with Cotocus and continue to contribute to multiple platforms where I share insights across different domains:

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