TweetFollow Us on Twitter

mac in the Shell: More ftp

Volume Number: 23 (2007)
Issue Number: 09
Column Tag: Mac in the shell

More ftp

I've got a fever, and the only prescription is more ftp

by Edward Marczak

Introduction

ftp – whether we're referring to the actual protocol, or just file transfer in general – is something we all need on some basis. When I started toying with computers, I saw punch cards, but never really had to deal with them. But that was only one method of file (or more generally, data) transfer. Then we moved up to tape and floppy disk. Now, very few computers are not connected to a network of some type, and the primary reason is to transfer data in the form of files. Our cover story this month touches on several GUI-based clients, but when you read this column, those utilities get the "Mac In The Shell" treatment. We need to be able to transfer files easily from a shell!

Why?

I often create automated solutions that run on a server without a GUI. There are also plenty of times when a simple, repeated file transfer shouldn't pop up anything visually on a client machine, either. It should 'just happen' simply and reliably with no pomp and circumstance. Enter curl, ftp and wget.

Of the three, "ftp" is the oldest and most simple. wget brings further power, and curl is a veritable Swiss Army Knife of transfer agents. If one of these options can't do what you want, it's most likely not possible (or, consider a different tactic!).

ftp

ftp, the application, implements a client side version of the ftp protocol (which is detailed by Mary Norbury in this month's cover story, "FTP Clients for Mac OS X"). In simple use, you can use it interactively:

$ ftp ftp.example.com
Trying ftp.example.com...
Connected to ftp.example.com.
220 example.com FTP server ready.
Name (ftp.example.com:marczak): 
331 Password required for marczak.
Password:
230 User marczak logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> cd Public
250 CWD command successful.
ftp> ls
229 Entering Extended Passive Mode (|||50077|)
150 Opening ASCII mode data connection for '/bin/ls'.
total 1
-rw-r--r--  1 marczak  marczak      0 Nov 16  2006 .localized
drwx-wx-wx  3 marczak  marczak    102 Nov 16  2006 Drop Box
-rw-r--r--  1 marczak  marczak  43796 Jul 20 07:14 test.jpg
226 Transfer complete.
ftp> bin
200 Type set to I.
ftp> get test.jpg
local: test.jpg remote: test.jpg
229 Entering Extended Passive Mode (|||50079|)
150 Opening BINARY mode data connection for 'test.jpg' (43796 bytes).
100% |********************| 43796     121.76 MB/s    00:00    
226 Transfer complete.
43796 bytes received in 00:00 (21.79 MB/s)
ftp> quit

Any techy person over the age of 25 should recognize this immediately. They should also remember in the days before big-business-on-the-Internet that it was polite to wait until "after hours" before using ftp against a University server! In the annals of tech-history, though, one needed to be familiar with transferring files this way.

The shell-based ftp application has a good lexicon in its interpreter. It's one that has grown substantially since its inception. However, for purposes of automation, that can get clumsy. You could script it with expect. Some versions of ftp allow creating a script and having ftp simply run through the motions that the script indicates. However, the version of ftp that ships with OS X (at least in Tiger) omits this option. It does keep the macro definition option in, though.

Never fear! The parameters available to you are greatly expanded, including passing a user name and password along. This is ideal for scripting within your own scripting environment. So, if I know in advance the names of the files I need to transfer, I could script this in bash thusly:

ftp -V ftp://user:password@server.example.com/directory/file.txt

...which will download file.txt and name the local file "file.txt". Note the -V switch, which is the opposite of -v – keeping the output quiet. I can also go the other way using:

ftp -V -u ftp://user:password@server.example.com/directory/ file.txt file2.txt 

...which will upload the specified file(s) – in this case, file.txt and file2.txt – to the given directory. Don't forget the trailing slash on the target directory!

Don't miss the fact that any valid URL syntax will work, so, you can 'ftp' a file from an HTTP server, too:

$ ftp http://www.example.com/directory/cars.jpg
Requesting http://www.example.com/directory/cars.jpg
 17746      29.87 KB/s

So, good 'ol ftp provides us with some quick and easy ways to move files around. Not ideal ways, perhaps, as not only is our password sent in the clear as part of the ftp protocol (which may not be an issue for you), but also displays our password in a process listing. That's not really cool.

ftp does offer many more options, so, check the man page if you need to get in deeper.

wget

wget bills itself as the "non-interactive network downloader." So, unlike ftp, there is no interactive mode with which you can use to generally poke around. However, we're here to talk about automated use, so, we don't need no stinkin interactive mode! If you were desperate, though, you could use one of wget's more interesting features: when an ftp directory is requested, it will automatically convert the output into an html listing. That might be a little too esoteric...even for me!

Disapointingly, wget is not installed by default under OS X Tiger. However, it's simple to install one way or another. You can grab the source from the GNU page at http://ftp.gnu.org/pub/gnu/wget/ and compile it yourself. Quentin Stafford-Fraser has a pre-compiled binary here: http://www.statusq.org/images/wget.zip. Finally, you can install wget using fink or MacPorts.

To get right down to it, like ftp, you can use any rational URL to specify your target:

$ wget ftp://emarczak:sekretpass@ftp.example.com/path/Big_File.zip
--07:23:08--  ftp://emarczak:*password*@ftp.example.com/path/Big_File.zip
           => `Big_File.zip'
Resolving ftp.example.com... 192.168.77.201
Connecting to ftp.example.com|192.168.77.201|:21... connected.
Logging in as emarczak ... Logged in!
==> SYST ... done.    ==> PWD ... done.
==> TYPE I ... done.  ==> CWD /path ... done.
==> PASV ... done.    ==> RETR Big_File.zip ... done.
Length: 10,871,922 (10M) (unauthoritative)
100%[=======================>] 10,871,922   638.53K/s    ETA 00:00
07:23:27 (601.74 KB/s) - `Big_File.zip' saved [10871922]

Also like ftp, wget will display your password in a process listing, so, use this with care! Here's where the roads diverge, though, and wget has a few more tricks up its sleeve. You can recursively download an entire ftp or http directory with the "-r" switch:

wget -r -t 5 ftp://emarczak:sekretpass@ftp.example.com/path/

I also threw in the "-t" switch, which will allows for multiple retries if some part of a file download fails. "-t" also allows for a value of "inf" causing infinite retries. Also useful here is the "-l" (ell) switch, which limits the depth of the traversal. So, to grab just the items from the top layer of the directory you specify, use "-l1".

An absolute life saver is the "-c" switch: it tells wget to continue a partial download. So, if your download bombs, or, perhaps you're on a laptop and need to run before the transfer is complete, retry the operation with the "-c" switch and pick up right from where you left off. Nice.

Wget will read a list of URLs from a file, using the "-i" switch. This is handy for scripting, of course. However, it's also a very nice way to keep your password out of a process listing. With your username and password embedded in a file, you're not using it on the command line. This list also comes in handy as a way to store your favorite sites and then recursively them locally using the "-r" switch mentioned above. In fact, toss in the "-A" switch, which will only accept certain files, and you can download only files of a certain type from a site. Next time you want all of the mov files from a given site, try this:

wget -r -l4 http://www.example.com/movies -A.mov -np

This will mirror the given site, and only transfer files ending in ".mov" on the given pages up to 4 levels deep. We also ensure that we don't follow links back up to the parent directory ("-np", or, "--no-parent").

Again, wget has many, many tricks up its sleeve. Too many to list here, but the brief introduction should convince you of its utility above the standard "ftp" application. Check out the man page for much more. (Specifically, check out the "-k" switch!).

curl

Like the other utilities mentioned here, curl will accept any valid URL as its file description. Unlike wget, curl is installed as a part of OS X. One very cool curl trick is that it dumps files to standard out unless it's told where to write them. Why is that cool?

Sometimes, you just want to view a remote document, be it an actual file – like a README or index.html file – or a directory listing. So, you could easily:

curl http://server2.example.com/instructions/how_to_do_it.txt | less

...which will get the file from the server and pipe it into less. When you quit less, there will be no file remaining to clutter up your disk. I sometimes use that with http://www.whatismyip.com, and then pipe the output to a script that simply reports back the machine's external IP address. This is also a cool way to run a remote script:

curl ftp://server.example.local/script.sh | bash

If you are interested in downloading a file, use the "-O" switch (capital O), which names the local file the same as the remote:

curl -O ftp://ftp.example.com/path/to/file/some_file.zip

This will anonymously download some_file.zip, and store it in the current working directory as some_file.zip. I also particularly like the "-L" switch (capital ell) when used with http servers as this will make curl follow http redirects.

Of course, curl will upload files, too. The "-T" switch will take care of this for you:

curl -T "pix[1-100].jpg" ftp://ftp.example.com/pictures/

I also threw in the fact that curl will respect globbing and regular expressions. So, the previous example will upload pix1.jpg, pix2.jpg...up through pix100.jpg. Clearly very handy.

Both upload and download can be resumed using the "-C -" switch (capital C followed by a hyphen). The hyphen tells curl to figure out where to resume from automatically. This does require server-side support in the form of telling the server at which byte to start appending at (the SIZE command for upload) or which byte to start the transfer from (ftp resume or HTTP 1.1 for downloads).

If you're an all-OS X shop, you'll be happy to hear that curl supports Kerberos. You can get your initial ticket the usual way (kinit), and then tell curl to use that authentication via the "--krb" switch.

curl --krb private ftp://krb4site.com -u username:boguspw

If this uses Kerberos, why did I still supply a name and password? This is a bit of a hack, but with no password, curl will still want to prompt you for one. However, if you supply one, but use Kerberos, it'll just ignore the password you supply – so use a bogus password as this will appear in process listings.

Conclusion

Being able to script data transfer is an important part of every system administrator's toolkit. While good 'old ftp will do the job in many cases, wget and curl give you much more flexibility. Both utilities have overlap in functionality, but curl goes deeper in many cases. Case in point: when I said that curl accepts any valid URL syntax, try TELNET://, dict:// and even LDAP:// (although, you'll currently need to build your own curl for LDAP support as the Apple supplied version isn't linked correctly with the LDAP framework).

Of course, there are other file transfer options available to you, including scp, sftp, ditto and rsync, to name a few. However, I focused mainly on ftp options here, as ftp is alive and well, but sometimes overlooked. While perhaps a deceiving name, sftp is not true ftp, but file transfer over ssh, requiring no ftp server at all. Of course, over "hostile" networks, you should use no less that an encrypted solution. However, with the right internal setup, and in certain other cases, ftp can be the perfect solution.

Media of the month: the ftp RFC: http://www.faqs.org/rfcs/rfc959.html. If you want to get deeper into ftp and understand why it behaves the way it does, this RFC is the way to go.

Please practice this in a test environment and then press it into real-world use where appropriate. Until next month, I think you'll find this a great tool in your automation arsenal.


Ed Marczak owns and operates Radiotope, a technology consulting company that guides companies to use what they have as efficiently as possible. He is also the Executive Editor of MacTech Magazine, a husband and father of two. His spare time is spent editing MacTech Magazine and enjoying his family. He finds keeping it all running smoothly good practice. Improve your practice at http://www.radiotope.com.

 
AAPL
$117.60
Apple Inc.
-1.03
MSFT
$47.47
Microsoft Corpora
-0.12
GOOG
$541.08
Google Inc.
+1.81

MacTech Search:
Community Search:

Software Updates via MacUpdate

MacUpdate Desktop 6.0.3 - Discover and i...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
SteerMouse 4.2.2 - Powerful third-party...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
iMazing 1.1 - Complete iOS device manage...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
PopChar X 7.0 - Floating window shows av...
PopChar X helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to access any font's special characters. Expanded... Read more
Carbon Copy Cloner 4.0.3 - Easy-to-use b...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
ForeverSave 2.1.3 - Universal auto-save...
ForeverSave auto-saves all documents you're working on while simultaneously doing backup versioning in the background. Lost data can be quickly restored at any time. Losing data, caused by... Read more
Voila 3.8.1 - Capture, annotate, organiz...
Voila is a screen-capture, recording, and annotation tool that is a full-featured replacement for Mac's screen-capture and screen-recording capabilities. It has a large and robust set of editing,... Read more
SyncTwoFolders 2.0.6 - Syncs two user-sp...
SyncTwoFolders simply synchronizes two folders. It supports synchronization across mounted network drives and it is a possibility to run a simulation showing in a log what will be done. Please visit... Read more
Duplicate Annihilator 5.1.1 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator detects... Read more
HandBrake 0.10.0 - Versatile video encod...
HandBrake is a tool for converting video from nearly any format to a selection of modern, widely supported codecs. Supported Sources: VIDEO_TS folder, DVD image or real DVD (unencrypted -- CSS is... Read more

Latest Forum Discussions

See All

Screeny (Utilities)
Screeny 1.0 Device: iOS iPhone Category: Utilities Price: $.99, Version: 1.0 (iTunes) Description: Screeny is an utility app that helps you save space consumed by screenshots. It screens your camera roll and helps you to filter and... | Read more »
Tilt to Live Bundle Set to Arrive This T...
Tilt to Live Bundle Set to Arrive This Thanksgiving Posted by Ellis Spice on November 25th, 2014 [ permalink ] One Man Left has unveiled an upcoming Tilt to Live bundle, allowing players to get the series for a di | Read more »
BattleLore: Command (Entertainment)
BattleLore: Command 1.0 Device: iOS Universal Category: Entertainment Price: $9.99, Version: 1.0 (iTunes) Description: ***NOTE: Compatible with iPad 2/iPad mini, iPod touch 5 and up and iPhone 4S and up – WILL NOT RUN ON EARLIER... | Read more »
Weather Or Not Review
Weather Or Not Review By Jennifer Allen on November 25th, 2014 Our Rating: :: STYLISH WEATHER REPORTINGiPhone App - Designed for the iPhone, compatible with the iPad Check the weather quickly and conveniently with Weather or Not... | Read more »
The All-New Football Manager Handheld 20...
The All-New Football Manager Handheld 2015 is Available Now Posted by Jessica Fisher on November 25th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Six iOS Games to Get You Ready for Thank...
Image Source: Friends Wiki At this point in the month, you or at least a few people you know are probably getting ready to scramble around (or are already scrambling around) for Thanksgiving Dinner. It’s a hectic day of precise oven utilization, but... | Read more »
Call of Duty: Heroes: Tips, Tricks, and...
Hello Heroes: What’d we think of Call of Duty‘s take on Clash of Clans? Check out our Call of Duty: Heroes review to find out! Just downloaded Call of Duty: Heroes and need some handy tips and tricks on how to get ahead of the rest? As we often do,... | Read more »
Call of Duty: Heroes Review
Call of Duty: Heroes Review By Jennifer Allen on November 25th, 2014 Our Rating: :: CLASH OF FRANCHISESUniversal App - Designed for iPhone and iPad Mix Clash of Clans with Call of Duty, and this is what you get.   | Read more »
Slider Review
Slider Review By Jordan Minor on November 25th, 2014 Our Rating: :: SLIDE TO PLAYUniversal App - Designed for iPhone and iPad Slider has all the excitement of unlocking your phone screen.   | Read more »
oh my giraffe (Games)
oh my giraffe 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Eat fruits while being chased by lions. Cut the vines to send fruit plummeting onto the lions. Don't worry, your flexible... | Read more »

Price Scanner via MacPrices.net

Early Black Friday MacBook Pro sale: 15-inch...
 Best Buy has posted early Black Friday prices on 15″ Retina MacBook Pros, with models on sale for $300 off MSRP on their online store for a limited time. Choose free local store pickup (if available... Read more
A9 Chips Already?
It’s barely more than a couple of months since Apple got the first A8 systems-on-chip into consumer hands, but rumor and news focus is already turning to the next-generation A9 SoC. Apple Daily... Read more
NewerTech Announces NuGuard KXs Impact X-Orbi...
NewerTech has announced updates to its family of Impact X-Orbing Screen Armor bringing military grade, triple layer protection to Apple’s new iPhone 6 and 6 Plus. Like all models in the NuGuard KXs... Read more
13-inch 1.4GHz MacBook Air on sale for $889,...
 B&H Photo has the 13″ 1.4GHz/128GB MacBook Air on sale for $889 including free shipping plus NY tax only. Their price is $110 off MSRP. B&H will also include free copies of Parallels Desktop... Read more
Save up to $300 on Macs and iPads with your A...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
Apple refurbished Mac Pros available for up t...
The Apple Store is offering Apple Certified Refurbished Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more
Jumptuit Launches One-Tap Windows 8.1 iTunes...
Jumptuit has launched Windows 8.1 support for One-Tap iTunes Sync. with which Windows 8.1 users can now easily sync their iTunes libraries with Microsoft OneDrive. Jumptuit provides easy access from... Read more
Apple restocks refurbished 13-inch 2014 Retin...
The Apple Store has restocked Apple Certified Refurbished 2014 13″ 2.6GHz Retina MacBook Pros for up to $230 off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
CEA Study Finds More People Recycling Electro...
A new study by the Consumer Electronics Association (CEA) finds that electronics recycling receives the continued and growing support of consumers. According to the CEA,s Recycling and Reuse Study,... Read more
15″ 2.2GHz Retina MacBook Pro on sale for $17...
 B&H Photo has the 2014 15″ 2.2GHz Retina MacBook Pro on sale today for $1749. Shipping is free, and B&H charges NY sales tax only. B&H will also include free copies of Parallels Desktop... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.