Shell Programming and Scripting

hi all,
problem 1.) i want to change the content of the file and save with the same name i get the solution like do a sed on that file and mv to same location. IS there any alternative solution of this???

problem 2) in this senario multiple scripts using a single file each script changes the content of the file will this work i mean whn one script chnaging the content and another script also comes into picture will second script wait for first script to relase the file whether second script wait or fail???????

and if problem 1 is doing its action like SED and MOV what heppen when second script comes in to action same time

Most scripts do not/cannot lock a file (depending on the OS). Your scripts will fail.
I cannot predict what will happen, but chances are you won't like it.

You best bet is to create a "traffic cop file" - a lock file. If every script abides nicely by the directions provided by the lock file then everything will be fine. Each script has to read and then update the lock file when it starts and when it ends. It has to do that even if it ends with an error or some kind trappable signal - you have to have trap statements.