I have been using the NetBSD ftpd server for some time specifically because of the on-the-fly conversion capability. Usually that is for gunziping files before transmission, but I have a more critical need - I use it to process data for anonymous users.
However, it seems that curl inquires about the size of the file before "get"ing it, and ftpd replies "550 <filename> not a plain file" when a file is subject to conversion, which is apparently treated as a fatal error by curl, and curl does not attempt to "get" the file. Here is a portion of the --verbose output from curl:
> TYPE I < 200 Type set to I. > SIZE NBERStostad.txm35 < 550 NBERStostad.txm35: not a plain file. * The file does not existAccording to this post (https://curl.se/mail/lib-2004-10/0035.html), if the SIZE command did not exist, curl would still work. It appears that existing and providing a specific error message is the getting in the way. I am not sure why curl bothers to issue the SIZE command when the --max-filesize option is left unspecified. It seems unnecessary.
Is there any way around this? The conversion feature is the primary reason for my using NetBSD.
Daniel Feenberg http://taxsim.nber.org/