How to use ftp in combination with .netrc

After answering a number of questions regarding automatic FTP on Unix-systems and the involvement of .netrc in it, I created this little guide.

Permissions and location of the .netrc

The .netrc should be in your home-directory and the permissions on the file should be unreadable for everybody except the owner:

[~] edwin@k7>ls -al .netrc
-rw-------  1 edwin  wheel  246 Aug 27 16:14 .netrc

You can set to these settings with chmod 600 .netrc.

Layout of the .netrc

Machine definitions

The first part of the .netrc is filled up with host-definitions:

machine ftp.freebsd.org
	login anonymous
	password [email protected]

machine myownmachine
	login myusername
	password mypassword

What it is saying now is nothing more than "If you connect to ftp.freebsd.org, login as anonymous and use [email protected] as password." and "If you connect to myownmachine, login as myusername and use mypassword as password.".

Macro definitions

This part of the .netrc consists of macros which can be used to perform automated tasks:

macdef uploadtest
	cd /pub/tests
	bin
	put filename.tar.gz
	quit

macdef dailyupload
	cd /pub/tests
	bin
	put daily-$1.tar.gz
	quit

Keep in mind that there should be an empty line after the last macdef statement. If you don't do this, ftp will complain about it.

The first one is saying "Go to the /pub/tests directory, switch to binary mode, put a file there and quit it". The second one is saying the same, except that the name of the file is based on a parameter on the macro-call (see Usage of the .netrc for more about this).

Usage of the .netrc

Macros can be called from both inside ftp:

[~] edwin@k7>ftp myownmachine
ftp: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
220 myownmachine FTP server (Version 6.00LS) ready.
331 Password required for myusername.
230 User myusername logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> $ uploadtest
cd temp
250 CWD command successful.
put filename.tar.gz
local: filename.tar.gz remote: filename.tar.gz
150 Opening BINARY mode data connection for 'filename.tar.gz'
100% |**************************************************|  1103       00:00 ETA
226 Transfer complete.
1103 bytes sent in 0.01 seconds (215.00 KB/s)
quit
221 Goodbye.

...or from on the command-line:

[~] edwin@k7>echo "\$ uploadtest" | ftp myownmachine
ftp: connect to address ::1: Connection refused
Trying 127.0.0.1...
100% |**************************************************|  1103       00:00 ETA

There is not much information here, because ftp doesn't expect a terminal here. If you use ftp -v, there will be more output.

An example with arguments is

[~] edwin@k7>echo "\$ dailyupload `date +'%Y%m%d'`"
$ dailyupload 20010827
[~] edwin@k7>echo "\$ dailyupload `date +'%Y%m%d'`" | ftp myownmachine
ftp: connect to address ::1: Connection refused
Trying 127.0.0.1...
100% |**************************************************|  1103       00:00 ETA

It will upload the file daily-20010827.tar.gz.

Debugging of ftp-sessions

What can go wrong

The only problems I've encountered are

• People forgetting to add an empty line after the last macdef statement.
• People with incorrect permissions on the .netrc-file.

Debugging

• If you are running the macro via the commandline, use the -v option to see more output.
• If you run ftp with the -d option you will get all commands send to the ftpd.