Erik Huelsmann wrote in a message to All:

 EH> Is there anybody there who can explain to me the limitations
 EH> multi-user programming will give me to file access?

I am not sure I understand what you mean by "multi-user."  OS/2
is a multi-tasking, but not a multi-user, operating system.

 EH> For example: I wanted to lock a file on multiple records,
 EH> but they were not in one sequence; they were these numbers:
 EH> 5 6 10 and 50

OS/2 handles locking by byte offset within a file.  It knows nothing about
records, which are details of organization imposed internally by your
program.

 EH> Share under WIN/OS2 would not let me lock them all. Is it so 
 EH> that I can only lock one record or subsequent area at a time?

Are you writing a native OS/2 program or a DOS/Windows program?

 EH> Any litterature on this subject would be greatly
 EH> appreciated. 

An OS/2 program can call DosSetFileLocks (or DosProtectSetFileLocks if
really paranoid), and can issue concurrent locks for multiple discontiguous
ranges. The details are available in the OS/2 Control Program Reference,
part of the OS/2 Toolkit.

Note that a common mistake is that you cannot assert overlapping lock
ranges for exclusive access.
 
-- Mike


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