overwrite: check if an existing file should be overwritten

Usage:

overwrite filename

Description:

overwrite presents the user with a dialog asking them if filename should be overwritten. A return value of 1 indicates that the file should be overwritten and a return value of 0 indicates that it should not.

The global variable NO_OVERWRITE controls whether or not the dialog box should be presented to the user. If NO_OVERWRITE is set to a non-zero value, filename will be overwritten without prompting the user.

Location:

/hhmi/nv3/hhmi/overwrite.tk