Look up the function to Get and Set File permissions. This will allow you to lock the file when you start and unlock it when your finished. =o)
Here's the sample from the help file:
The Set Permissions function includes a permissions input that allows you to control access to files and directories that you create. To define the permissions you want to set, you can wire the permissions output of the Get Permissions function to the permissions input of the Set Permissions function, or you can wire a constant or a control.
The 9 bits that the permissions parameter uses are divided into three sets: user, group, and others. Each set is divided into three permission categories: read, write, and execute. Read determines if members of a set can read a file or directory. Write determines if members of a set can write data to a file or directory. Execute determines if members of a set can execute the file. A 1 in the bit grants permission.
For example, the following illustration shows how to grant a user permission to read from, write to, and execute a file, and deny permission from the other two sets.
Octal format shortens each three-bit group within the parameter to a single octal value. (Windows) For example, to make a file read-only, enter the octal value 200, which corresponds to the binary representation 10000000. (Linux) To grant users read, write, and execute permissions, enter the octal value 700, which corresponds to the binary value 111000000.
