Several questions here....
The most fundamental is "what is inode?" - you need to understand this if you want to use the filesystem functions in PHP.
The inode system (simply and not necessarily accurately explained) is the fundamental makeup of the Unix filesystem.
<SOAPBOX me="on"> You may well be aware of "other" filesystems that call the Primary master hard drive things like "C", these systems treat each file as a file and each directory as a directory and arrange things nicely on the disk to fit this. Great but not very efficient because if I move a file on this file system and then rename it no detail whatsoever will remain about the file from before and the operating system will physically shove it across the disk to it's new home.
In Unix everything has an inode - think of it as a reference number and all files are just stored in a big lump. Now imagine there's a table of data and the columns are Inode, path, filename. Once a file is created its added to the table and given an inode - the inode will not change, I can rename the file and all that happens is the filename entry in the data table changes for that inode, if I move the file it doesn't really get shoved across the disk - the path for the inode changes in the table. .... and of course the inode is still the same, so you can do all manner of things to a file even move it and rename it and still find it by its inode number. This is one of the many reasons why Windows is crap and Unix is good if you want to do more than just draw pretty pictures and send bulky HTML emails.
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The php manual explains the difference between created and modified times for files and using the functions themselves. It also explains that not all Unix based systems treat these things the same and you didn't explain which Unix you were using - is it HPUX, Sco, a Linux derivative?????
