I just did at clean Drupal install to a subdirectory of my webdomain, and got the error message "No input file specified." when going to the root of my install directory, like "www.webdomain.com/subdirectory".
Specifying "install.php" like "www.webdomain.com/subdirectory/install.php"did not help either. Same error message again and again. Clearing cache. Fixing accessattributes. Renaming subdirectory. Nothing helped.
I finally found the problem:
When installing Drupal in a subdirectory, or even in the bare root at some webhosts, there could be a problem with the following Options in the default ".htaccess" file in the root of the Drupal install directory. Simply edit the ".htaccess" file and comment out the following options putting a "#" in front like this:
# Don't show directory listings for URLs which map to a directory.
#Options -Indexes
# Follow symbolic links in this directory.
#Options +FollowSymLinks
Hope this helps you too :)
Comments
PHP Apache module
Also make sure that PHP runs as Apache module (not CGI). If using Plesk, there may be a wrong default option in domain settings for that.
htaccess rewrite Base
Also, in the .htaccess, L.102 and nexts :
# Modify the RewriteBase if you are using Drupal in a subdirectory or in a
# VirtualDocumentRoot and the rewrite rules are not working properly.
# For example if your site is at http://example.com/drupal uncomment and
# modify the following line:
# RewriteBase /drupal
#
# If your site is running in a VirtualDocumentRoot at http://example.com/,
# uncomment the following line:
# RewriteBase /
You might need to uncomment on of these.
Check Your Server Settings
Another possibility may be if there are server-specific settings needed to be applied to your .htaccess
For instance, on one of my installs, CGI-PHP (cgiwrap) is how Drupal is run. When updates to core are applied, this information can get overwritten, and the "No input file specified." message will pop up.