Ns returnfile

ns_returnfile 200 "application/zip" $filepath
ns_returnfile 200 [ns_guesstype $file] $filepath

Caveat programmor

ns_returnfile uses fastpath caching internally, and fastpath caching may fail to distinguish between two files on the same filesystem which have the same inode, mtime, and size (serving one file in lieu of the other). This can happen if a file is generated, returned to the user, and then deleted. For example, in the following sample code the second call to ns_returnfile will return /var/tmp/myfile rather than /var/tmp/myotherfile:

set file [open "/var/tmp/myfile" "w"]
puts $file "ABC123"
close $file
ns_returnfile 200 text/plain "/var/tmp/myfile"
ns_unlink -nocomplain "/var/tmp/myfile"

set file [open "/var/tmp/myotherfile" "w"]
puts $file "XYZ987"
close $file
ns_returnfile 200 text/plain "/var/tmp/myotherfile"
ns_unlink -nocomplain "/var/tmp/myotherfile"

When returning "dynamic" file data like this, a safer practice would be to use ns_return or ns_returnfp instead (since they don't use fastpath caching). For example:

set fd [open $myfile]
ns_return 200 [ns_guesstype $myfile] [read $fd]
close $fd

Want to name the file returned as well?

ns_set update [ns_conn outputheaders] content-disposition "attachment; filename=1.abc" -