try to play around with the nmap command...
something along the lines nmap $1 $1.txt
quoting for the FTP man page
nmap [inpattern outpattern]
Set or unset the filename mapping mechanism. If no arguments are
specified, the filename mapping mechanism is unset. If arguments are
specified, remote filenames are mapped during mput commands and put
commands issued without a specified remote target filename. If argu-
ments are specified, local filenames are mapped during mget commands
and get commands issued without a specified local target filename.
This command is useful when connecting to a non-UNIX remote computer
with different file naming conventions or practices. The mapping
follows the pattern set by inpattern and outpattern. [Inpattern] is
a template for incoming filenames (which may have already been pro-
cessed according to the ntrans and case settings). Variable templat-
ing is accomplished by including the sequences `$1', `$2', ..., `$9'
in inpattern. Use `\' to prevent this special treatment of the `$'
character. All other characters are treated literally, and are used
to determine the nmap [inpattern] variable values. For example,
given inpattern $1.$2 and the remote file name "mydata.data", $1
would have the value "mydata", and $2 would have the value "data".
The outpattern determines the resulting mapped filename. The
sequences `$1', `$2', ...., `$9' are replaced by any value resulting
from the inpattern template. The sequence `$0' is replace by the
original filename. Additionally, the sequence `[seq1, seq2]' is
replaced by [seq1] if seq1 is not a null string; otherwise it is
replaced by seq2. For example, the command
nmap $1.$2.$3 [$1,$2].[$2,file]
would yield the output filename "myfile.data" for input filenames
"myfile.data" and "myfile.data.old", "myfile.file" for the input
filename "myfile", and "myfile.myfile" for the input filename
".myfile". Spaces may be included in outpattern, as in the example:
`nmap $1 sed "s/ *$//" > $1' . Use the `\' character to prevent
special treatment of the `$','[',']', and `,' characters.