linux命令行下查看扩展是否开启

使用 php -m 命令

$ php -m 
[PHP Modules]
bcmath
Core
ctype
curl
date
dom
ereg
fileinfo
filter
gd
hash
iconv
json
libxml
mbstring
mysql
mysqli
mysqlnd
openssl
pcre
PDO
pdo_sqlite
Phar
posix
Reflection
session
SimpleXML
SPL
sqlite3
standard
tokenizer
xdebug
xml
xmlreader
xmlwriter
zip
zlib

[Zend Modules]
Xdebug

查看具体哪个扩展可以结合grep，如查看gd

$ php -m | grep -i gd
gd

phpinfo浏览器查看php扩展库

<?php
phpinfo();

页面显示的每一个表格的标题，即是已经安装的扩展。

get_loaded_extensions获取开启的所有PHP扩展

<?php
print_r(get_loaded_extensions());

Array
(
    [0] => Core
    [1] => date
    [2] => ereg
    [3] => libxml
    [4] => openssl
    [5] => pcre
    [6] => sqlite3
    [7] => zlib
    [8] => bcmath
    [9] => ctype
    [10] => curl
    [11] => dom
    [12] => fileinfo
    [13] => filter
    [14] => gd
    [15] => hash
    [16] => json
    [17] => mbstring
    [18] => SPL
    [19] => session
    [20] => standard
    [21] => mysqlnd
    [22] => PDO
    [23] => pdo_sqlite
    [24] => Phar
    [25] => posix
    [26] => Reflection
    [27] => mysqli
    [28] => SimpleXML
    [29] => mysql
    [30] => tokenizer
    [31] => xml
    [32] => xmlreader
    [33] => xmlwriter
    [34] => zip
    [35] => cgi-fcgi
    [36] => iconv
    [37] => xdebug
)

extension_loaded判断php扩展是否加载

<?php
var_dump(extension_loaded('gd'));
// 输出true 或者 false