some refactoring + support for multiple directories with and without incremental backups

backup.cfg

@@ -1,5 +1,4 @@
 protocol=ssh # ftp, sftp, ftps, ssh or local
-source_dir=/home/user/source
 remote_host=hostname.tld
 backup_dir=relative_or_full_path
 #snap_file=/var/backup/snapshot.list
@@ -7,3 +6,6 @@ backup_dir=relative_or_full_path
 compress_format=xz # gz, bz2, xz or empty for non-compressed
 remote_user=username
 remote_pass=PassWd
+source_dirs=( '/home/user/source1:/var/backup/snapshot.list' )
+
+# vim: ft=zsh

backup.zsh

@@ -1,17 +1,16 @@
 #!/usr/bin/env zsh
-set -e
 self_name=$0
+default_cfg='/usr/local/etc/backup.cfg'
+default_postfix=$(date +%F-%H%M)
 
 function err
 {
-	[[ -n $2 ]] && echo $2 >&2
-	return $1
+	[[ -n $1 ]] && echo $1 >&2
 }
 
 function cfg_err
 {
 	[[ -n $1 ]] && echo "$1 is not set in configuration, but is required by $0 to work." >&2
-	return 5
 }
 
 function usage
@@ -19,50 +18,35 @@ function usage
 	echo "usage: $self_name [--help|--config]
 	--help    -h - show this message
 	--config  -c - use config from the specified path
-	
+
 	Default config path /usr/local/etc/backup.cfg will be used if invoked without options"
 }
 
-function read_config
+# function to read the configuration file and spit out some exceptions if stuff is missing
+function apply_config
 {
 	source $cfg || err 15 'Config file does not exist'
-	[[ -z $source_dir ]] && cfg_err 'Backup source'
-	[[ -z $remote_host ]] && cfg_err 'Remote host'
-	[[ -z $protocol ]] && cfg_err 'Backup protocol'
-	[[ -z $backup_dir && $protocol != 'ssh' ]] && cfg_err 'Target directory'
+	[[ -z $source_dirs ]] && { cfg_err 'Backup source'; exit 5 }
+	[[ -z $remote_host ]] && { cfg_err 'Remote host'; exit 5 }
+	[[ -z $protocol ]] && { cfg_err 'Backup protocol'; exit 5 }
+	[[ -z $backup_dir && $protocol != 'ssh' ]] && { cfg_err 'Target directory'; exit 5 }
 	if [[ -z $local_host ]]; then
 		local_host=$HOST
 	fi
-	src_basename=${source_dir:t}
-	src_basedir=${source_dir:h}
-}
-
-function generate_fullpath
-{
-	local backup_type
-	local postfix
+	# date postfix
 	if [[ -z $outfile_postfix ]]; then
 		postfix=$default_postfix
 	else
 		postfix=$outfile_postfix
 	fi
-	if [[ -s $snap_file ]]; then
-		backup_type='incr'
-	else
-		backup_type='full'
-	fi
-	if [[ -z $backup_filename ]]; then
-		outfile="$backup_dir/${local_host}-${src_basename}_${postfix}_${backup_type}.t${compress_format:-'ar'}"
-	else
-		outfile=$backup_filename
+	if [[ -z $remote_port ]]; then
+		case $protocol in
+			('ftp'|'ftps') remote_port='21';;
+			('sftp'|'ssh') remote_port='22';;
+			('local') unset remote_port;;
+			(*) err 1 "$protocol is not a valid value for the protocol option.";;
+		esac
 	fi
-}
-
-function compress # compress to stdout
-{
-	local compress_flag
-	local exclude_option
-	local snapshot_option
 	case $compress_format in
 		('xz') compress_flag='J' ;;
 		('bz2') compress_flag='j' ;;
@@ -84,19 +68,32 @@ function compress # compress to stdout
 			err 1 "Snapshot file $snap_file cannot be written."
 		fi
 	fi
+}
+
+# generate the full backup path
+function generate_fullpath
+{
+	local backup_type
+	# increment or full backup
+	if [[ -s $snap_file ]]; then
+		backup_type='incr'
+	else
+		backup_type='full'
+	fi
+	if [[ -z $backup_filename ]]; then
+		outfile="$backup_dir/${local_host}-${src_basename}_${postfix}_${backup_type}.t${compress_format:-'ar'}"
+	else
+		outfile=$backup_filename
+	fi
+}
+
+function compress # compress to stdout
+{
 	tar cf$compress_flag - -C $src_basedir $src_basename $snapshot_option $snapshot_file $exclude_option $exclude_list --ignore-failed-read
 }
 
 function store # store to local or remote
 {
-	if [[ -z $remote_port ]]; then
-		case $protocol in
-			('ftp'|'ftps') remote_port='21';;
-			('sftp'|'ssh') remote_port='22';;
-			('local') unset remote_port;;
-			(*) err 1 "$protocol is not a valid value for the protocol option.";;
-		esac
-	fi
 	case $protocol in
 		('local') dd of=$outfile ;;
 		('ssh') ssh -p$remote_port $remote_user@$remote_host "dd of=$outfile" ;;
@@ -105,7 +102,7 @@ function store # store to local or remote
 	esac
 }
 
-function main
+function parse_opts
 {
 	while [[ -n $1 ]]; do
 		case $1 in
@@ -113,11 +110,25 @@ function main
 			('--config'|'-c') shift; opt_cfg=$1; shift;;
 		esac
 	done
-	cfg=${opt_cfg:-'/usr/local/etc/backup.cfg'}
-	default_postfix=$(date +%F-%H%M)
-	read_config
-	generate_fullpath
-	compress | store
+}
+
+function main
+{
+	parse_opts
+	if [[ -z $opt_cfg ]]; then
+		cfg=$default_cfg
+	else
+		cfg=$opt_cfg
+	fi
+	apply_config
+	for i in $source_dirs; do
+		unset src_basename src_basedir outfile
+		IFS=':' read source_dir snap_file <<< $i
+		src_basename=${source_dir:t}
+		src_basedir=${source_dir:h}
+		generate_fullpath
+		compress | store
+	done
 	return 0
 }