How composer check php version? - php

Question

I just wondering how composer check which php to use when check for requirements. I use MacOS and in terminal type:
composer require phpunit/phpunit
the result is something like:
Problem 1
- phpunit/phpunit 5.0.4 requires php >=5.6 -> your PHP version (5.5.27) or "config.platform.php" value does not satisfy that requirement....
When I check php version:
php -v
The result is:
PHP 5.6.10 (cli) (built: Jun 12 2015 14:08:56) Copyright (c) 1997-2015
The PHP Group Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend
Technologies
with Xdebug v2.2.5, Copyright (c) 2002-2014, by Derick Rethans
Which is:
which php
php: aliased to /Applications/MAMP/bin/php/php5.6.10/bin/php
Can someone explain this. Thanks in advance!

Answer 1

Composer can tell you what version of PHP it's running on, if you specify debug verbosity -vvv.
I like to run it with the about command, since the output is relatively short.
composer -vvv about
Example output:
...
Running 1.8.5 (2019-04-09 17:46:47) with PHP 7.3.5 on Darwin / 18.6.0
...
Edit:
This has gotten more interest than I expected, so here's a version with cleaner output:
composer -vvv about 2>&1 | grep "PHP"

Answer 2

On MacOs X the default installation of php resides in /usr/bin. If you upgrade your php it will most likely be installed somewhere else (like /usr/local/php5), or if you use MAMP or something else it will be elsewhere. Just make sure that the first occurrence of php when traversing your PATH is the same as the version your webserver is using. (like have /usr/local/php5/bin before /usr/bin in your PATH). That will solve your problem.

Answer 3

If you used a package install method, such as apt-get on Ubuntu, chances are that the executable will include a "shebang" pointing to the specific php that should be used to run that specific composer file.
When using the command composer the cli will first resolve which binary to use. By running which composer you can find what binary that is.
$ which composer
/usr/bin/composer
Once you know that, you can open the file, for instance using vim: vim /usr/bin/composer (generally it takes super user access to modify binaries so you shouldn't be able to mess composer up doing that).
On the first line of the composer binary should be a shebang, possibly looking like #!/usr/bin/php that would instruct the composer executable on how it should run.
You can then call that php binary directly to verify its version:
/usr/bin/php -v

Answer 4

( sharing this here because I was looking for it an landed here but nothing satisfied me so I will share for those who land here for the same reason: )
With the following command you can check which composer packages depend on a specific php version:
composer depends php | grep 8.1
will output something like:
symfony/console v6.1.4 requires php (>=8.1)
symfony/css-selector v6.1.3 requires php (>=8.1)
symfony/deprecation-contracts v3.1.1 requires php (>=8.1)
symfony/error-handler v6.1.3 requires php (>=8.1)
symfony/event-dispatcher v6.1.0 requires php (>=8.1)
symfony/event-dispatcher-contracts v3.1.1 requires php (>=8.1)
symfony/finder v6.1.3 requires php (>=8.1)
symfony/http-foundation v6.1.4 requires php (>=8.1)
symfony/http-kernel v6.1.4 requires php (>=8.1)
symfony/mailer v6.1.4 requires php (>=8.1)
symfony/mime v6.1.4 requires php (>=8.1)
symfony/process v6.1.3 requires php (>=8.1)
symfony/routing v6.1.3 requires php (>=8.1)
symfony/service-contracts v3.1.1 requires php (>=8.1)
symfony/string v6.1.4 requires php (>=8.1)
symfony/translation v6.1.4 requires php (>=8.1)
symfony/translation-contracts v3.1.1 requires php (>=8.1)
symfony/var-dumper v6.1.3 requires php (>=8.1)