This is a backup script around rsync, it pulls files from 
a remote server in the local machine through ssh. 

USAGE:
transfer [ [ -r REMOTE ] [ -l LOCAL ] [ -s SUBJECT ] 
  [ -p PREFIX ] [ -b BASE ] [ -d ] ] | [ -v ] | [ -h ] 

OPTIONS:
  -r: remote hostname, default: localhost
  -l: local hostname, default: localhost (for metadata only)
  -s: subject, a grouping for backups, e.g. apache, 
      default: files
  -b: base destination, default: /var/backups/hosts.d/
      you can't use a relative path with this parameter
  -p: prefix for all source paths
  -d: debug, set echo on the shell
  -v: version, print version number
  -h: help, print this message

By default backups are stored in /var/backups/hosts.d/

Inside for every different remote, a folder will
be kept.

A subject parameter intended to specify either a service
or otherwise know set of files further distinguishes the 
contents.

e.g. /var/backups/hosts.d/example.net/vhosts

Inside this folder even further distinction is made, 3 
different folders establish the status of the copies:

tmp: meanwhile a copy is being made
err: if the script is interrupted or the transmission fails
ok: when the script finishes successfully

The final distinction is the date the copy was run. 
A symbolic link is present on the ok folder 
pointing to the last copy.

A copy holds various plain text files with info on
when and how was the backup made, including the remote and 
local hostnames, the start, and finish time, size of the
archive, status, etc. 

Finally along with the metadata the data.d folder holds the 
actual files, keeping the full original path, file 
permissions, etc.

When possible the last ok copy of the same particular set of
files is used for hardlinking, saving space.

transfer takes input from stdin, one folder/file per line, 
currently if you need null terminated paths, you can set a wrapper 
around rsync, presetting the -0 parameter, the same goes for 
excluding files.

EXAMPLE:

transfer -r example.net -s apache <<EOF_APACHE
/var/www/
/srv/www/
/etc/apache2/
EOF_APACHE

ENVIRONMENT:

RSYNC: name of the rsync executable or a wrapper
DATEFMT: date format used for backup directories

Changing default values:

REMOTE: -r, LOCAL: -l, SUBJECT: -s, DEST_BASE: -b, PREFIX: -p

Parameters take precedence.