The
purpose of
ncftp
is to provide a powerful and flexible interface to the
Internet standard
File Transfer Protocol.
It is intended to replace the stock
ftp
program that comes with the system.
Although the program appears to be rather spartan,
you'll find that
ncftp
has a wealth of valuable performance and usage features.
The program was designed with an emphasis on usability,
and it does as much as it can for you automatically so you can do what
you expect to do with a file transfer program, which is transfer files
between two interconnected systems.
Some of the cooler features include progress meters, filename completion,
command-line editing, background processing, auto-resume downloads,
bookmarking, cached directory listings, host redialing,
working with firewalls and proxies,
downloading entire directory trees, etc., etc.
The
ncftp
distribution comes with the useful utility programs
ncftpget(1)
and
ncftpput(1)
which were designed to do command-line FTP.
In particular, they are very handy for shell scripts.
This version of
ncftp
no longer does command-line FTP, since
the main
ncftp
program is more of a browser-type program.
OPTIONS
The program allows you to specify a host or directory URL
on the command line. This is a synonym for running
ncftp
and then using the
open
command.
A few command-line flags are allowed with this mode:
-u XX
Use username
XX
instead of anonymous.
-p XX
Use password
XX
with the username.
-j XX
Use account
XX
in supplement to the username and password (deprecated).
-P XX
Use port number
XX
instead of the default FTP service port (21).
INTRODUCTION TO THE COMMAND SHELL
Upon running the program you are presented a command prompt
where you type commands to the
program's shell.
Usually you will want to open a remote filesystem to transfer files
to and from your local machine's filesystem.
To do that, you need to know the symbolic name of the remote system,
or its
Internet Protocol
(IP) address.
For example, a symbolic name might be ``typhoon.unl.edu,'' and its IP
address could be ``129.93.33.24.''
To open a connection to that system, you use the program's
open
command:
open typhoon.unl.edu
open 129.93.33.24
Both of these try to open the machine called typhoon at the
University of Nebraska.
Using the symbolic name is the preferred way, because IP addresses may
change without notice, while the symbolic names usually stay the same.
When you open a remote filesystem, you need to have permission.
The
FTP Protocol's
authentication system is very similar to that of
logging in to your account.
You have to give an account name, and its password for access to that
account's files.
However, most remote systems that have anything you might be interested
in don't require an account name for use.
You can often get anonymous access to a remote filesystem and exchange
files that have been made publicly accessible.
The program attempts to get anonymous permission to a remote system by
default.
What actually happens is that the program tries to use ``anonymous'' as
the account name, and when prompted for a password, uses your E-mail address
as a courtesy to the remote system's maintainer.
You can have the program try to use a specific account also.
That will be explained later.
After the
open
command completes successfully, you are connected to the remote system
and logged in.
You should now see the command prompt change to reflect the name
of the current remote directory.
To see what's in the current remote directory, you can use the program's
ls and dir
commands. The former is terse, preferring more remote files
in less screen space, and the latter is more verbose, giving detailed
information about each item in the directory.
You can use the program's
cd
command to move to other directories on the
remote system.
The cd command behaves very much like the command of the same name in the
Bourne and Korn shell.
The purpose of the program is to exchange data with other systems.
You can use the program's
get
command to copy a file from the remote system to your local system:
get README.txt
The program will display the progress of the transfer on the screen, so
you can tell how much needs to be done before the transfer finishes.
When the transfer does finish, then you can enter more commands to the
program's command shell.
You can use the program's
put
command to copy a file from your system to the remote system:
put something.tar
When you are finished using the remote system, you can open another one
or use the
quit
Before quitting, you may want to save the current FTP session's
settings for later.
You can use the
bookmark
command to save an entry into your
$HOME/.ncftp/bookmarks
file. When you use the
bookmark
command, you also specify a bookmark name, so the next time instead of
opening the full hostname you can use the name of the bookmark.
A bookmark acts just like one for your web browser, so it saves the
remote directory you were in, the account name you used, etc., and other
information it learned so that the next time you use the bookmark it should
require as little effort from you as possible.
COMMAND REFERENCE
help
The first command to know is
help.
If you just type
help
from the command shell, the program prints the names of all of the supported
commands.
From there, you can get specific help for a command by typing the command
after, for example:
help open
prints information about the
open
command.
ascii
This command sets the transfer type to ASCII text.
This is useful for text-only transfers because the concept of
text files differs between operating systems.
For example on UNIX, a text file denotes line breaks with the
linefeed character, while on MS-DOS a line break is denoted by
both a carriage return character and a line feed character.
Therefore, for data transfers that you consider the data as text
you can use
ascii
to ensure that both the remote system and local system translate
accordingly.
The default transfer type that
ncftp
uses is not ASCII, but straight binary.
bgget and bgput
These commands correspond to the
get and put
commands explained below, except that they do the job in the background.
Normally when you do a
get
then the program does the download immediately, and does not return
control to you until the download completes.
The background transfers are nice because you can continue browsing
the remote filesystem and even open other systems.
In fact, they are done by a daemon process, so even if you log off
your UNIX host the daemon should still do your transfers.
The daemon will also automatically continue to retry the transfers
until they finish.
To tell when background jobs have finished, you have to examine the
$HOME/.ncftp/spool/log
file, or run the
jobs
command from within
NcFTP.
Both the
bgget and bgput
commands allow you to schedule when to do the transfers.
They take a ``-@'' parameter, whose argument is a date
of the form YYYYMMDDhhmmss
(four digit year, month, day, hour, minute, second).
For example, to schedule a download at 3 AM on November 6,
you could try:
This command tells
ncftp
to immediately start the background transfers you've requested, which
simply runs a copy of the
ncftpbatch
program which is responsible for the background jobs.
Normally the program will start the background job as soon as you close
the current site, open a new site, or quit the program.
The reason for this is because since so many users still use slow
dialup links that starting the transfers would slow things to a crawl,
making it difficult to browse the remote system.
An added bonus of starting the background job when you close the site
is that
ncftp
can pass off that open connection to the
ncftpbatch
program.
That is nice when the site is always busy, so that the background job
doesn't have to wait and get re-logged on to do its job.
binary
Sets the transfer type to raw binary, so that
no translation is done on the data transferred.
This is the default anyway, since most files are in binary.
bookmark
Saves the current session settings for later use.
This is useful to save the remote system and remote working directory
so you can quickly resume where you left off some other time.
The bookmark data is stored in your
$HOME/.ncftp/bookmarks
file.
bookmarks
Lists the contents of your
$HOME/.ncftp/bookmarks
file in a human-readable format.
You can use this command to recall the bookmark name of a previously
saved bookmark, so that you can use the
open
command with it.
cat
Acts like the ``/bin/cat''
UNIX
command, only for remote files.
This downloads the file you specify and dumps it directly to the
screen.
You will probably find the
page
command more useful, since that lets you view the file one screen
at a time instead of printing the entire file at once.
cd
Changes the working directory on the remote host.
Use this command to move to different areas on the remote server.
If you just opened a new site, you might be in the root directory.
Perhaps there was a directory called ``/pub/news/comp.sources.d''
that someone told you about.
From the root directory, you could:
cd pub
cd news
cd comp.sources.d
or, more concisely,
cd /pub/news/comp.sources.d
Then, commands such as
get, put, and ls
could be used to refer to items in that directory.
Some shells in the
UNIX
environment have a feature I like, which is switching to the previous
directory.
Like those shells, you can do:
cd -
to change to the last directory you were in.
chmod
Acts like the ``/bin/chmod''
UNIX
command, only for remote files.
However, this is not a standard command, so remote FTP servers
may not support it.
close
Disconnects you from the remote server.
The program does this for you automatically when needed, so you can simply
open other sites or quit the program without worrying about closing the
connection by hand.
debug
This command is mostly for internal testing.
You could type
debug 1
to turn debugging mode on.
Then you could see all messages between the program and the remote
server, and things that are only printed in debugging mode.
However, this information is also available in the
$HOME/.ncftp/trace
file, which is created each time you run
ncftp.
If you need to report a bug, send a
trace
file if you can.
dir
Prints a detailed directory listing.
It tries to behave like
UNIX's
``/bin/ls -l'' command.
If the remote server seems to be a
UNIX
host, you can also use the same flags you would with
ls, for instance
dir -rt
would try to act like
/bin/ls -lrt
would on
UNIX.
get
Copies files from the current working directory on the
remote host to your machine's current working directory.
To place a copy of ``README'' and ``README.too''
in your local directory, you could try:
get README README.too
You could also accomplish that by using a wildcard expression,
such as:
get README*
This command is similar to the behavior of other FTP programs'
mget
command.
To retrieve a remote file but give it a different name on your
host, you can use the ``-z'' flag.
This example shows how to download a file called
ReadMe.txt
but name it locally as
README:
get -z ReadMe.txt README
The program tries to ``resume'' downloads by default.
This means that if the remote FTP server lost the connection
and was only able to send 490 kilobytes of a 500 kilobyte
file, you could reconnect to the FTP server and do another
get
on the same file name and it would get the last 10 kilobytes,
instead of retrieving the entire file again.
There are some occasions where you may not want that behavior.
To turn it off you can use the ``-f'' flag.
There are also times where you want to append to an existing
file.
You can do this by using the ``-A'' flag, for example
get -A log.11
would append to a file named ``log.11'' if it existed locally.
Another thing you can do is delete a remote file after you
download it.
This can be useful when a remote host expects a file to be
removed when it has been retrieved.
Use the double-D flag, such as ``get -DD'' to do this.
The
get
command lets you retrieve entire directory trees, too.
Although it may not work with some remote systems, you can
try ``get -R'' with a directory to download the directory
and its contents.
jobs
Views the list of currently executing
NcFTP
background tasks.
This actually just runs
ncftpbatch -l
for you.
lcd
The
lcd
command is the first of a few ``l'' commands that work with the local host.
This changes the current working directory on the local host.
If you want to download files into a different local directory, you could
use
lcd
to change to that directory and then do your downloads.
lchmod
Runs ``/bin/chmod'' on the local host.
lls
Another local command that comes in handy is the
lls
command, which runs ``/bin/ls'' on the local host and displays the results
in the program's window.
You can use the same flags with
lls
as you would in your command shell, so you can do things like:
lcd ~/doc
lls -lrt p*.txt
lmkdir
Runs ``/bin/mkdir'' on the local host.
lookup
The program also has a built-in interface to the name service via
the
lookup
command.
This means you can lookup entries for remote hosts, like:
You can also give
IP
addresses, so this would work too:
lookup 129.93.33.24
prints:
typhoon.unl.edu 129.93.33.24
lpage
Views a local file one page at a time, with your preferred
$PAGER program.
lpwd
Prints the current local directory.
Use this command when you forget where you are on your local machine.
lrename
Runs ``/bin/mv'' on the local host.
lrm
Runs ``/bin/rm'' on the local host.
lrmdir
Runs ``/bin/rmdir'' on the local host.
ls
Prints a directory listing from the remote system.
It tries to behave like
UNIX's
``/bin/ls -CF'' command.
If the remote server seems to be a
UNIX
host, you can also use the same flags you would with
ls, for instance
ls -rt
would try to act like
/bin/ls -CFrt
would on
UNIX.
ncftp
has a powerful built-in system for dealing with directory listings.
It tries to cache each one, so if you list the same directory, odds
are it will display instantly.
Behind the scenes,
ncftp
always tries a long listing, and then reformats it as it needs to.
So even if your first listing of a directory was a regular ``ls''
which displayed the files in columns, your next listing could be
``ls -lrt'' and
ncftp
would still use the cached directory listing to quickly display the
information for you!
mkdir
Creates a new directory on the remote host.
For many public archives, you won't have the proper access permissions to
do that.
open
Establishes an FTP control connection to a remote host.
By default,
ncftp
logs in anonymously to the remote host.
You may want to use a specific user account when you log in,
so you can use the ``-u'' flag to specify which user.
This example shows how to
open
the host ``bowser.nintendo.co.jp''
using the username ``mario:''
open -u mario bowser.nintendo.co.jp
Here is a list of options available for use with the
open
command:
-u XX
Use username
XX
instead of anonymous.
-p XX
Use password
XX
with the username.
-j XX
Use account
XX
in supplement to the username and password (deprecated).
-P XX
Use port number
XX
instead of the default FTP service port (21).
page
Browses a remote file one page at a time, using your $PAGER program.
This is useful for reading README's on the remote host without downloading
them first.
pdir and pls
These commands are equivalent to
dir and ls
respectively, only they feed their output to your pager.
These commands are useful if the directory listing scrolls off your screen.
put
Copies files from the
local host to the remote machine's current working directory.
To place a copy of ``xx.zip'' and ``yy.zip''
in the remote directory, you could try:
put xx.zip yy.zip
You could also accomplish that by using a wildcard expression,
such as:
put *.zip
This command is similar to the behavior of other FTP programs'
mput
command.
To send a remote file but give it a different name on your
host, you can use the ``-z'' flag.
This example shows how to upload a file called
``ncftpd-2.0.6.tar.gz''
but name it remotely as
``NFTPD206.TGZ:''
put -z ncftpd-2.0.6.tar.gz NFTPD206.TGZ
The program
does not
try to ``resume'' uploads by default.
If you do want to resume an upload, use the ``-z'' flag.
There are also times where you want to append to an existing
remote file.
You can do this by using the ``-A'' flag, for example
put -A log11.txt
would append to a file named ``log11.txt'' if it existed
on the remote server.
Another thing you can do is delete a local file after you
upload it.
Use the double-D flag, such as ``put -DD'' to do this.
The
put
command lets you send entire directory trees, too.
It should work on all remote systems, so you can
try ``put -R'' with a directory to upload the directory
and its contents.
pwd
Prints the current remote working directory.
A portion of the pathname is also displayed in the
shell's prompt.
quit
Of course, when you finish using the program, type
quit
to end the program
(You could also use
bye, exit, or ^D).
quote
This can be used to send a direct
FTP Protocol
command to the remote server.
Generally this isn't too useful to the average user.
rename
If you need to change the name of a remote file, you can use the
rename
command, like:
rename SPHYGMTR.TAR sphygmomanometer-2.3.1.tar
rhelp
Sends a help request to the remote server.
The list of
FTP Protocol
commands is often printed, and sometimes some other information that is
actually useful, like how to reach the site administrator.
Depending on the remote server, you may be able to give a parameter to
the server also, like:
rhelp NLST
One server responded:
Syntax: NLST [ <sp> path-name ]
rm
If you need to delete a remote file you can try the
rm
command.
Much of the time this won't work because you won't have the proper
access permissions.
This command doesn't accept any flags, so you can't nuke a whole tree
by using ``-rf'' flags like you can on
UNIX.
rmdir
Similarly, the
rmdir
command removes a directory.
Depending on the remote server, you may be able to remove a non-empty
directory, so be careful.
set
This lets you configure some program variables, which are saved
between runs in the
$HOME/.ncftp/prefs
file.
The basic syntax is:
set <option> <value>
For example, to change the value you use for the anonymous password, you
might do:
See the next section for a list of things you change.
show
This lets you display program variables.
You can do ``show all'' to display all of them,
or give a variable name to just display that one, such as:
show anon-password
site
One obscure command you may have to use someday is
site.
The
FTP Protocol
allows for ``site specific'' commands.
These ``site'' commands vary of course, such as:
site chmod 644 README
Actually,
ncftp's chmod
command really does the above.
Try doing one of these to see what the remote server supports, if any:
rhelp SITE
site help
type
You may need to change transfer types during the course of a session with
a server.
You can use the
type
command to do this. Try one of these:
type ascii
type binary
type image
The
ascii
command is equivalent to ``type a'', and the
binary
command is equivalent to ``type i'' and ``type b''.
umask
Sets the process'
umask
on the remote server, if it has any concept of a umask, i.e.:
umask 077
However, this is not a standard command, so remote FTP servers
may not support it.
version
This command dumps some information about the particular edition of the
program you are using, and how it was installed on your system.
VARIABLE REFERENCE
anon-password
Specifies what to use for the password when logging in anonymously.
Internet convention has been to use your E-mail address as a
courtesy to the site administrator.
If you change this, be aware that some sites require (i.e. they
check for) valid E-mail addresses.
auto-resume
NcFTP
3 now prompts the user by default when you try to download
a file that already exists locally, or upload a file that
already exists remotely.
Older versions of the program automatically guessed whether to overwrite
the existing file or attempt to resume where it left off,
but sometimes the program would guess wrong.
If you would prefer that the program always guess which
action to take, set this variable to
yes,
otherwise, leave it set to
no
and the program will prompt you for which action to take.
autosave-bookmark-changes
With the advent of version 3 of
NcFTP,
the program treats bookmarks more like they would with your
web browser, which means that once you bookmark the site,
the remote directory is static.
If you set this variable to
yes,
then the program will automatically update the bookmark's
starting remote directory with the directory you were in
when you closed the site.
This behavior would be more like that of
NcFTP
version 2.
confirm-close
By default the program will ask you when a site you haven't
bookmarked is about to be closed.
To turn this prompt off, you can set this variable to
no.
connect-timeout
Previous versions of the program used a single timeout value for everything.
You can now have different values for different operations.
However, you probably do not need to change these from the defaults
unless you have special requirements.
The
connect-timeout
variable controls how long to wait, in seconds, for a connection establishment
to complete before considering it hopeless.
You can choose to not use a timeout at all by setting this to -1.
control-timeout
This is the timer used when
ncftp
sends an FTP command over the control connection to the remote server.
If the server hasn't replied in that many seconds, it considers the session
lost.
logsize
This is controls how large the transfer log
($HOME/.ncftp/log) can grow to, in kilobytes.
The default is 200, for 200kB;
if you don't want a log, set this to 0.
pager
This is the external program to use to view a text file, and is
more
by default.
passive
This controls
ncftp's
behavior for data connections, and can be set to one of
on, off, or the default, optional.
When passive mode is on,
ncftp
uses the
FTP command primitive
PASV
to have the client establish data connections to the server.
The default FTP protocol behavior is to use the FTP command primitive
PORT
which has the server establish data connections to the client.
The default setting for this variable,
optional,
allows
ncftp
to choose whichever method it deems necessary.
progress-meter
You can change how the program reports file transfer status.
Select from meter
2, 1, or 0.
redial-delay
When a host is busy or unavailable, the program waits
this number of seconds before trying again.
The smallest you can set this is to 10 seconds --
so if you were planning on being inconsiderate,
think again.
save-passwords
If you set this variable to
yes,
the program will save passwords along with the bookmarks you save.
While this makes non-anonymous logins more convenient, this can
be very dangerous since your account information is now sitting
in the
$HOME/.ncftp/bookmarks
file.
The passwords aren't in clear text, but it is still trivial to
decode them if someone wants to make a modest effort.
so-bufsize
If your operating system supports TCP Large Windows,
you can try setting this variable to the number of bytes to
set the TCP/IP socket buffer to. This option won't be of
much use unless the remote server also supports large window
sizes and is pre-configured with them enabled.
xfer-timeout
This timer controls how long to wait for data blocks to complete.
Don't set this too low or else your transfers will timeout without
completing.
FIREWALL AND PROXY CONFIGURATION
You may find that your network administrator has placed a firewall
between your machine and the Internet, and that you cannot reach
external hosts.
The answer may be as simple as setting
ncftp
to use
passive
mode only, which you can do from a
ncftp
command prompt like this:
set passive on
The reason for this is because many firewalls do not allow incoming
connections to the site, but do allow users to establish outgoing
connections.
A passive data connection is established by the client to the server,
whereas the default is for the server to establish the connection to the
client, which firewalls may object to.
Of course, you now may have problems with sites whose
primitive FTP servers do not support passive mode.
Otherwise, if you know you need to have
ncftp
communicate directly with a firewall or proxy, you can try
editing the separate
$HOME/.ncftp/firewall
configuration file.
This file is created automatically the first time you run the
program, and contains all the information you need to get
the program to work in this setup.
The basics of this process are configuring a firewall (proxy)
host to go through, a user account and password for authentication
on the firewall, and which type of firewall method to use.
You can also setup an exclusion list, so that
ncftp
does not use the firewall for hosts on the local network.
FILES
$HOME/.ncftp/bookmarks
Saves bookmark and host information.
$HOME/.ncftp/firewall
Firewall access configuration file.
$HOME/.ncftp/prefs
Program preferences.
$HOME/.ncftp/trace
Debugging output for entire program run.
$HOME/.ncftp/v3init
Used to tell if this version of the program has run before.
$HOME/.ncftp/spool/
Directory where background jobs are stored in the form of
spool configuration files.
$HOME/.ncftp/spool/log
Information for background data transfer processes.
ENVIRONMENT
PATH
User's search path, used to find the
ncftpbatch
program, pager, and some other system utilities.
PAGER
Program to use to view text files one page at a time.
TERM
If the program was compiled with support for
GNU Readline
it will need to know how to manipulate the terminal correctly for
line-editing, etc.
The pager program will also take advantage of this setting.
HOME
By default, the program writes its configuration data in a
.ncftp
subdirectory of the
HOME
directory.
NCFTPDIR
If set, the program will use this directory instead of
$HOME/.ncftp.
This variable is optional except for those users whose home directory is
the root directory.
COLUMNS
Both the built-in
ls
command and the external
ls
command need this to determine how many screen columns the terminal has.
BUGS
There are no such sites named
bowser.nintendo.co.jp
or
sphygmomanometer.unl.edu.
Auto-resume should check the file timestamps instead of relying upon
just the file sizes, but it is difficult to do this reliably within
FTP.
Directory caching and recursive downloads depend on
UNIX-like
behavior of the remote host.
Thanks to everyone who uses the program.
Your support is what drives me to improve the program!
I thank Dale Botkin and Tim Russell at my former ISP,
Probe Technology.
Ideas and some code contributed by my partner, Phil Dietz.
Thanks to Brad Mittelstedt and Chris Tjon, for driving and refining
the development of the backbone of this project,
LibNcFTP.
I'd like to thank my former system administrators, most notably Charles Daniel,
for making testing on a variety of platforms possible, letting me have
some extra disk space, and for maintaining the UNL FTP site.
For testing versions 1 and 2 above and beyond the call of duty,
I am especially grateful to:
Phil Dietz,
Kok Hon Yin, and
Andrey A. Chernov ([email protected]).
Thanks to Tim MacKenzie ([email protected]) for the
original filename completion code for version 2.3.0 and 2.4.2.
Thanks to DaviD W. Sanderson ([email protected]), for helping me out with
the man page.
Thanks to those of you at UNL who appreciate my work.
Thanks to Red Hat Software for honoring my licensing agreement, but more
importantly, thanks for providing a solid and affordable development platform.
APOLOGIES
To the users, for not being able to respond personally to most of your
inquiries.
To Phil, for things not being the way they should be.
