So you've like read some directions somewhere out there with something like

chmod the file 755  and the directory 700

First off, the chmod command .. this is Linux'ese for CHange MODe , eg; changing the mode of the file, besides permissions, it can also change something called a sticky bit .. but I'll save that for a later time.

So what about those numbers ?

There will always be 3 digits, sometimes 4, with the first being zero, like

0755  and 755

These are identical as far as chmod is concerned, so for simplicity I'll stick with the 3 digit format. 

The first number, sets the permissions of the file owner. That is most likely you, or possibly your webserver's process

The second number sets the permissions for the group members, but today this is rarely used since the typical Linux user is in a group of one.

The last number sets the permssion for everyone else, as such, its the one that will most likely cause issues if incorrect. Its also the one you should as conservative as possible with..

chmod 700 private_file.txt

Ok.. perhaps, we'll allow just members of our group to view the file content by giving them read (4) permssions

chmod 740 private_file.txt 

Ok, maybe the info isn't so private anymore.. allow anyone to read the file 

chmod 744 private_file.txt  

Perhaps allow group members to edit the file, by adding write (2) permissions ..

chmod 764 private_file.txt  

Typically, files that make up a wbesite should be 

chmod 755 

Full permissions for the file/directory owner, read and execute permissions for everyone else.

BUT.. sometimes, you need something different. Hopefully this little note will help you to determine what permissions you actually need, and how to make that change yourself.

Regards,

Dewed