What is a reliable way to automate FTP upload of 'the newest file in directory X'?

Question

I have this folder full of files.

Once per day, I want the newest of the files to be FTPed automatically to a file server.

Answer 1

Make a short script, get the filename via this line:

newestfilename=`ls -t $dir| head -1`

(assuming $dir is the directory you're interested in), then feed $filename to your FTP command, and of course, cron this script to run once a day.

If you have ncftp, you can use the following command to ftp the file:

ncftpput -Uftpuser -Pftppasswd ftphost /remote/path $dir/$newestfilename

Without ncftp, this may work:

ftp -u ftp://username:passwd@ftp.example.com/path/to/remote_file $dir/$newestfilename

Answer 2

Locating the newest file

The easiest way to find the newest file in a directory is to use zsh and its glob qualifiers om to sort by modification time and [1] to pick the most recent match.

upload /path/to/dir/*(om[1])

There's no good, portable method. The only portable method is to use ls -t to list files by date and parse the result, but parsing ls is fraught with dangers. Do this only if you're sure that your file names contain no newlines or non-printable characters.

upload "$(ls -t /path/to/dir | head -n 1)"

FTP upload

For the upload, there are many tools. A commonly installed one is curl.

curl -T /path/to/local/file ftp://ftp.example.com/remote/dir

Another approach is to mount the remote directory as a filesystem, for example with curlftpfs.

mkdir ftp.example.com
curlftpfs ftp.example.com ftp.example.com
cp -p /path/to/local/file ftp.example.com/remote/dir/

Automating the task

Add a crontab entry to perform the task every day. Run crontab -e and add a line like this:

SHELL=/bin/zsh
42 3 * * * curl -T /path/to/dir/*(om[1]) ftp://ftp.example.com/remote/dir