tl;dr

Here’s how to install yaz on Ubuntu 20.04 with PHP 7.4:

sudo apt install yaz libyaz-dev php-dev php-pear
sudo pecl install yaz

The libyaz-dev package is the important, and oft-overlooked part.

Then add the following line to /etc/php/7.4/apache2/php.ini:

extension=yaz.so

And restart apache:

sudo systemctl restart apache2

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Original post from 4 years ago follows.

Numerous sites on the internet have answered the basic question of “how do I install yaz for PHP on Ubuntu”. Which basically boils down to some flavor of:

PHP 5.x

sudo apt-get install yaz
sudo apt-get install pecl      # Ubuntu pre-16.04
sudo apt-get install php-pear  # Ubuntu 16.04 and later
sudo pecl install yaz

Then add the following line to /etc/php5/apache2/php.ini:

extension=yaz.so

PHP 7.0

sudo apt-get install yaz
sudo apt-get install php7.0-dev php7.0-pear
# might just be php-dev and php-pear on your OS (eg: Ubuntu 16.04)
sudo pecl install yaz

Then add the following line to /etc/php/7.0/apache2/php.ini:

extension=yaz.so

But wait, that fails

Sadly, the pecl install will fail with the error:

checking for yaz-config... NONE
configure: error: YAZ not found (missing NONE)
ERROR: `/tmp/pear/temp/yaz/configure --with-yaz' failed

All the search results for this error solve it by downloading the yaz source code and compiling and installing it outside the package manager, which is non-ideal.

The missing piece is that yaz-config is included with the libyaz4-dev package:

sudo apt-get install libyaz4-dev

Interestingly, this yaz install blog post does explicitly calls out the need for the -dev packages, but doesn’t include the error when you don’t have it. Hopefully this blog post will tie the two bits together for future people perplexed by this.

Updates:

• 2018-06-03: include PHP 7.0 instructions for Ubuntu 16.04.
• 2020-12-05: include PHP 7.4 instructions for Ubuntu 20.04.