UNIX for Dummies Questions & Answers

Hi folks, can you help me decipher this?

I know that ftp will accept input from all commands until it encounters EOF again but I don't quite make sense of what the entirety of the script is really trying to achieve.

Many thanks.

Code:

ftp -n someserver << EOF | head -20
user username@server password
ascii
ls -lt
EOF 
exit

It is called a here document - like typing the stuff live into ftp, but the script does the "typing".

The "<<EOF" and "EOF", mark the boundaries of the here doc. << EOF is the start, EOF (in absolutely the first column) marks the end.

"EOF" can be almost anything that is not a variable or a command, old stinkers like me use an exclamation point: !

EOF is sort of a de facto standard for that. You could use FARKLE or AuntMartha
if you wanted to.

In summary the script tries to display a directory list of the most recent 20 files from the remote server.

The script is showing the first 20 lines (head -20) of the output of a simple ftp session which displays a directory listing from the remote system.
The ftp session logs in with username and password changes the file transfer mode to "ascii" (not "binary") and asks the remote system for a directory list. Whether this directory list will actually come out in descending date order (ls -tr) is a matter of implementation of ftp on the servers involved.
The "ascii" command is pointless in this context but a good reminder to positively set ascii/binary when actually moving files.

The script could be improved by placing a ftp "quit" command as the last ftp command before the "EOF".