Programming

Hi All,

I am facing an issue... I need to replace some string in a text file while the same file is read by some other user at the same time. The other user is using it in the Read only mode. So I can't create a temporary file and write the content first and then write it back into the original file.

Please let me know if anyone have any sample code (C/C++) or any info related to this issue.

Thanks in advance!!!

Look at the mmap function as it does what you are trying to do here...one process maps a file as shared into its address space while the other process accesses it in read only mode.

This only works if the read-only user has it mapped in, not when they get it via read().

The consequences of changing data in the middle of a file while in use are unknown and potentially bad. They may just be ignored if the data's already been checked once. Catch it at the right moment and it may only see partial changes. Even with the right timing, the program may react badly to having the floor changed from underneath it. Doing this to a shell script for example will probably cause it to bomb out with syntax errors.