UNIX for Dummies Questions & Answers

I have a program (written by me, for educational purposes) called "analyzer".

The program takes a parameter, a filename, and does some statistics on it (for example, word's number, line's number, ... ) at regular intervals.

My teacher told me that if the file is edited while the "analyzer" is on, the program may not be aware of the changes, because some editors using x-server (as gedit) create a new i-node and a new session for the file, different from the i-node the "analyzer" is using.

Can someone explain this step, please?
Thank you in advance for your attention.

P.S. I'm sorry if my English is not accurate.

Hurricane,

Changing a file while a process is running is always a dicey situation.

One situation can be demonstrated by moving or copying a file. If you move it, that file will retain it's "INode" or it's number, it will just reside in a different directory. If you copy it, you're actually creating a new file, with a new number.

Processes identify files by number. If you were to move a file while it is being saved, it will still save correctly to the new location, because you're still using the same number.

This is the situation.

I wrote a very simple and small program that closes its standard output and redirects it on a file.

Another program (called "analyzer" in the previous post) does some statistics, as words' number, characters' number, ...

If I edit the file from the first process, the second process (the "analyzer") updates its statistics, while if I edit the file from editors (as TextEdit, or nano, ...), the "analyzer" doesn't update its results as long as the edited file is not explicitly saved.

Why?

Hurricane:

Most (since I don't know all of them, I cannot say "all") editors copy the file to be editted into memory, which is what you edit. The memory copy is written back to the file, replacing it's contents, when you save.

Also, one tiny clarification:
A file will retain its inode only if the move is within the same filesystem.

Ludwig, thank you for the clarification.