more refactoring and fixing, now fully functional and with a documented config

backup.cfg

@@ -1,11 +1,50 @@
-protocol=ssh # ftp, sftp, ftps, ssh or local
+#### general options ####
-remote_host=hostname.tld
+## The protocol we want to use to store our backups.
-backup_dir=relative_or_full_path
+## Can be ftp, sftp, ftps, ssh or local.
-#snap_file=/var/backup/snapshot.list
+protocol='ssh'
-#exclude_list=/usr/local/etc/backup/excludes.list
+
-compress_format=xz # gz, bz2, xz or empty for non-compressed
+## The directory store backups in, locally or remotely.
-remote_user=username
+backup_dir='relative_or_full_path'
-remote_pass=PassWd
+
-source_dirs=( '/home/user/source1:/var/backup/snapshot.list' )
+## The list of patterns to exclude from backups, for
+## more details look into tar -X option.
+#exclude_list='/usr/local/etc/backup/excludes.list' 
+
+## The compression algorithm for backups.
+## Can be gz, bz2, xz or empty (for non-compressed).
+compress_format='xz'
+
+## An array with the set of directories within it.
+## Optionally snapshot file can be added to store
+## incremental diffs (tar -g option used).
+## You'll have to deal with snapshots on your own:
+## backup.zsh only handles backups (i.e. you can remove
+## snapshot via cron on regular basis to ensure that
+## full backups are created from time to time.)
+source_dirs=( '/home/user/source1:/var/backup/snapshot.list'
+              '/etc' '/var/spool/mail:/var/backup/spool_snapshot.list' )
+
+## Use with caution, the file existance is not checked
+## on execution.
+## Since this config is sourced, I advise adding some
+## logic for that, or you can handle filename collisions
+## externally.
+#backup_filename='somebackup'
+
+#### remote options ####
+## Remote host.
+remote_host='hostname.tld'
+
+## Remote user.
+remote_user='username'
+
+## Password, due to how openssh handles security it only
+## works for *ftp* protocols; backups via ssh protocol
+## work interactively. Later versions will have support
+## for ssh keys.
+remote_pass='PassWd'
+
+## Port is optional, the defaults are hardcoded.
+#remote_port='443'
 
 # vim: ft=zsh

backup.zsh

@@ -1,6 +1,6 @@
 #!/usr/bin/env zsh
 self_name=$0
-default_cfg='/usr/local/etc/backup.cfg'
+default_cfg='/etc/backup.zsh.cfg'
 default_postfix=$(date +%F-%H%M)
 default_ftp_port='21'
 default_ssh_port='22'
@@ -12,35 +12,51 @@ function err
 
 function cfg_err
 {
-	[[ -n $1 ]] && echo "$1 is not set in configuration, but is required by $0 to work." >&2
+	[[ -n $1 ]] && echo "$1 is not set in configuration, but is required by $self_name to work." >&2
 }
 
 function usage
 {
-	echo "usage: $self_name [--help|--config]
+	echo "usage: $self_name [--help|--conf /path/to/config]
-	--help    -h - show this message
+	--help  -h   show this message
-	--config  -c - use config from the specified path
+	--conf  -c   use config from the specified path
 
-	Default config path /usr/local/etc/backup.cfg will be used if invoked without options"
+	Default config path $default_cfg will be used if invoked without options"
 }
 
 # 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'
+	function test_remote_settings
+	{
+		if [[ -z $remote_host ]]; then
+			cfg_err 'remote_host'
+			return 5
+		fi
+		if [[ -z $remote_user ]]; then
+			cfg_err 'remote_user'
+			return 5
+		fi
+		if [[ -z $remote_pass ]]; then
+			cfg_err 'remote_pass'
+			return 5
+		fi
+		if [[ -n $port && ! $port =~ ^[0-9]+$ ]]; then
+			err 'Remote port is not a numeric value.'
+			return 5
+		fi
+	}
+	source $cfg || { err "Config file $cfg is unreadable or does not exist"; return 15 }
 	if [[ -z $source_dirs ]]; then
-		cfg_err 'Backup source'
+		cfg_err 'source_dirs'
-		exit 5
+		return 5
-	fi
-	if [[ -z $remote_host ]]; then
-		cfg_err 'Remote host'
-		exit 5
 	fi
 	if [[ -z $backup_dir && $protocol != 'ssh' ]]; then
-		cfg_err 'Target directory'
+		cfg_err 'backup_dir'
-		exit 5
+		return 5
 	fi
 	if [[ -z $local_host ]]; then
+		err 'local_host is not set, using hostname.'
 		local_host=$HOST
 	fi
 	# date postfix
@@ -50,20 +66,17 @@ function apply_config
 		postfix=$outfile_postfix
 	fi
 	case $protocol in
-		('ftp'|'ftps') port=${remote_port:-$default_ftp_port};;
+		('ftp'|'ftps') port=${remote_port:-$default_ftp_port}; test_remote_settings; return $?;;
-		('sftp'|'ssh') port=${remote_port:-$default_ssh_port};;
+		('sftp'|'ssh') port=${remote_port:-$default_ssh_port}; test_remote_settings; return $?;;
 		('local') unset remote_port;;
-		(*) cfg_err 'Backup protocol'; exit 5;;
+		(*) cfg_err 'protocol'; return 5;;
 	esac
-	if [[ ! $remote_port =~ ^[0-9]+$ ]]; then
-		err 'Remote port is not a numeric value.'
-	fi
 	case $compress_format in
 		('xz') compress_flag='J' ;;
 		('bz2') compress_flag='j' ;;
 		('gz') compress_flag='z' ;;
 		('') unset compress_flag; unset compress_format ;;
-		(*) err "$compress_format is not a valid value for the compression format option."; exit 5;;
+		(*) err "$compress_format is not a valid value for the compression format option."; return 5;;
 	esac
 	if [[ -n $exclude_list ]]; then
 		if [[ -r $exclude_list ]]; then
@@ -72,13 +85,6 @@ function apply_config
 			err "Exclusion list $exclude_list is either unreadable or does not exist."
 		fi
 	fi
-	if [[ -n $snap_file ]]; then
-		if printf '' >> $snap_file; then
-			snapshot_option='-g'
-		else
-			err "Snapshot file $snap_file cannot be written."
-		fi
-	fi
 }
 
 # generate the full backup path
@@ -86,7 +92,7 @@ function generate_fullpath
 {
 	local backup_type
 	# increment or full backup
-	if [[ -s $snap_file ]]; then
+	if [[ -s $snapshot_file ]]; then
 		backup_type='incr'
 	else
 		backup_type='full'
@@ -100,7 +106,14 @@ function generate_fullpath
 
 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
+	if [[ -n $snapshot_file ]]; then
+		if printf '' >> $snapshot_file; then
+			snapshot_option='-g'
+		else
+			err "Snapshot file $snapshot_file cannot be written."
+		fi
+	fi
+	tar -c$compress_flag $snapshot_option $snapshot_file $exclude_option $exclude_list --ignore-failed-read -C $src_basedir $src_basename
 }
 
 function store # store to local or remote
@@ -116,27 +129,28 @@ function parse_opts
 {
 	while [[ -n $1 ]]; do
 		case $1 in
-			('--help'|'-h') usage; return 0;;
+			('--help'|'-h') usage; exit 0;;
-			('--config'|'-c') shift; opt_cfg=$1; shift;;
+			('--conf'|'-c') shift; opt_cfg=$1; shift;;
+			('') opt_cfg=$default_cfg;;
+			(*) err "unknown parameter $1"; exit 127;;
 		esac
 	done
 }
 
 function main
 {
-	parse_opts
+	parse_opts $@
-	if [[ -z $opt_cfg ]]; then
+	cfg=${opt_cfg:-$default_cfg}
-		cfg=$default_cfg
-	else
-		cfg=$opt_cfg
-	fi
 	apply_config
+	local apply_config_returns=$?
+	[[ $apply_config_returns -ne 0 ]] && return $apply_config_returns
 	for i in $source_dirs; do
 		unset src_basename src_basedir outfile
-		IFS=':' read source_dir snap_file <<< $i
+		IFS=':' read source_dir snapshot_file <<< $i
 		src_basename=${source_dir:t}
 		src_basedir=${source_dir:h}
 		generate_fullpath
+		echo "Creating a backup of $source_dir. Using protocol $protocol to store it in $outfile."
 		compress | store
 	done
 	return 0