On Windows NT+ and Windows Server 2000+:
Go to Control Panel and open the System icon (Start -> Settings -> Control Panel -> System, or just Start -> Control Panel -> System for Windows XP/2003+)
Go to the Advanced tab
Click on the 'Environment Variables' button
Look into the 'System Variables' pane
Find the Path entry (you may need to scroll to find it)
Double click on the Path entry
Enter your PHP directory at the end, including ';' before (e.g. ;C:\php)
On Windows 98/Me you need to edit the autoexec.bat file:
Open the Notepad (Start -> Run and enter notepad)
Open the C:\autoexec.bat file
Locate the line with PATH=C:\WINDOWS;C:\WINDOWS\COMMAND;….. and add: ;C:\php to the end of the line
Save the file and restart your computer
Note: Be sure to reboot after following the steps above to ensure that the PATH changes are applied.
The PHP manual used to promote the copying of files into the Windows system directory, this is because this directory (C:\Windows, C:\WINNT, etc.) is by default in the systems PATH. Copying files into the Windows system directory has long since been deprecated and may cause problems.
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