Align backup on USB with backup on NFS

doc/rear.8

@@ -551,7 +551,7 @@ OUTPUT_URL=nfs://server/path/
 .\}
 .RE
 .sp
-When using BACKUP=NETFS and BACKUP_PROG=tar there is an option to select BACKUP_TYPE=incremental or BACKUP_TYPE=differential to let rear make incremental or differential backups until the next full backup day e\&.g\&. via FULLBACKUPDAY="Mon" is reached or when the last full backup is too old after FULLBACKUP_OUTDATED_DAYS has passed\&. Incremental or differential backup is currently only known to work with BACKUP_URL=nfs\&. Other BACKUP_URL schemes may work but at least BACKUP_URL=usb is known not to work with incremental or differential backup\&.
+When using BACKUP=NETFS and BACKUP_PROG=tar there is an option to select BACKUP_TYPE=incremental or BACKUP_TYPE=differential to let rear make incremental or differential backups until the next full backup day e\&.g\&. via FULLBACKUPDAY="Mon" is reached or when the last full backup is too old after FULLBACKUP_OUTDATED_DAYS has passed\&. Incremental or differential backup is currently only known to work with BACKUP_URL=nfs\&. Other BACKUP_URL schemes may work but at least BACKUP_URL=usb requires USB_SUFFIX to be set to work with incremental or differential backup\&.
 .SH "CONFIGURATION"
 .sp
 To configure Relax\-and\-Recover you have to edit the configuration files in \fI/etc/rear/\fR\&. All \fI*\&.conf\fR files there are part of the configuration, but only \fIsite\&.conf\fR and \fIlocal\&.conf\fR are intended for the user configuration\&. All other configuration files hold defaults for various distributions and should not be changed\&.

doc/rear.8.adoc

@@ -388,8 +388,8 @@ e.g. via +FULLBACKUPDAY="Mon"+ is reached or when the last full backup
 is too old after FULLBACKUP_OUTDATED_DAYS has passed.
 Incremental or differential backup is currently only known to work
 with +BACKUP_URL=nfs+. Other BACKUP_URL schemes may work but
-at least +BACKUP_URL=usb+ is known not to work with incremental
-or differential backup.
+at least +BACKUP_URL=usb+ requires USB_SUFFIX to be set
+to work with incremental or differential backup.
 
 == CONFIGURATION
 To configure Relax-and-Recover you have to edit the configuration files in

doc/user-guide/03-configuration.adoc

@@ -135,8 +135,8 @@ e.g. via +FULLBACKUPDAY="Mon"+ is reached or when the last full backup
 is too old after FULLBACKUP_OUTDATED_DAYS has passed.
 Incremental or differential backup is currently only known to work
 with +BACKUP_URL=nfs+. Other BACKUP_URL schemes may work but
-at least +BACKUP_URL=usb+ is known not to work with incremental
-or differential backup.
+at least +BACKUP_URL=usb+ requires USB_SUFFIX to be set
+to work with incremental or differential backup.
 
 BACKUP=REQUESTRESTORE::
 No backup, just ask user to somehow restore the filesystems.

usr/share/rear/conf/default.conf

@@ -356,7 +356,27 @@ USB_UEFI_PART_SIZE="100"
 # resulting files that should be copied onto the USB stick
 USB_FILES=()
 
-# Number of rescue environments/backups to retain on USB
+# USB_SUFFIX specifies the last part of the backup directory on the USB medium.
+# When USB_SUFFIX is unset or empty, backup on USB works in its default mode which means
+# multiple timestamp backup directories of the form rear/HOSTNAME/YYYYMMDD.HHMM
+# plus automated rescue environments and backups cleanup via USB_RETAIN_BACKUP_NR.
+# In contrast when USB_SUFFIX is set, backup on USB works in compliance with how backup on NFS works
+# (i.e. BACKUP_URL=usb:... and BACKUP_URL=nfs:... behave compatible when USB_SUFFIX is set)
+# which means a fixed backup directory of the form rear/HOSTNAME/USB_SUFFIX on the USB medium
+# and no automated removal of backups or other stuff (regardless of USB_RETAIN_BACKUP_NR)
+# see https://github.com/rear/rear/issues/1164
+# Using multiple backups as described in doc/user-guide/11-multiple-backups.adoc
+# requires a fixed backup directory so that USB_SUFFIX must be set for multiple backups on USB
+# see https://github.com/rear/rear/issues/1160
+# Also BACKUP_TYPE incremental or differential requires a fixed backup directory
+# so that USB_SUFFIX must be set for incremental or differential backup on USB
+# see https://github.com/rear/rear/issues/1145
+USB_SUFFIX=""
+
+# Number of older rescue environments or backups to retain on USB.
+# The default USB_RETAIN_BACKUP_NR=2 means that there is at most
+# the latest (current) rescue environment or backup plus
+# the second eldest and the third eldest (three all together):
 USB_RETAIN_BACKUP_NR=2
 
 # Define the default WORKFLOW for the udev handler (empty to disable)
@@ -494,8 +514,8 @@ BACKUP_INTEGRITY_CHECK=
 # By default BACKUP_TYPE is empty which means "rear mkbackup" will create a full backup.
 # Only with BACKUP=NETFS and BACKUP_PROG=tar one can also use incremental or differential backup:
 # Incremental or differential backup is currently only known to work with BACKUP_URL=nfs://.
-# Other BACKUP_URL schemes may work but at least BACKUP_URL=usb:///... is known not to work
-# with incremental or differential backup (see https://github.com/rear/rear/issues/1145).
+# Other BACKUP_URL schemes may work and at least BACKUP_URL=usb:///... requires USB_SUFFIX to be set
+# to work with incremental or differential backup (see https://github.com/rear/rear/issues/1145).
 # Incremental or differential backup and NETFS_KEEP_OLD_BACKUP_COPY contradict each other so that
 # NETFS_KEEP_OLD_BACKUP_COPY must not be 'true' in case of incremental or differential backup
 # because NETFS_KEEP_OLD_BACKUP_COPY would move an already existing backup directory away

usr/share/rear/output/USB/Linux-i386/300_create_extlinux.sh

@@ -103,10 +103,22 @@ fi
 
 # We generate a single syslinux.cfg for the current system
 Log "Creating $USB_PREFIX/syslinux.cfg"
+# FIXME: # type -a time
+#        time is a shell keyword
+#        time is /usr/bin/time
 time=$(basename $USB_REAR_DIR)
+if test $USB_SUFFIX ; then
+    # USB_SUFFIX specifies the last part of the backup directory on the USB medium
+    # and then basename $USB_REAR_DIR can be anything so that we use it as is:
+    menu_label="$time"
+else
+    # When USB_SUFFIX is unset, empty, or contains only blanks
+    # basename $USB_REAR_DIR is a timestamp of the form YYYYMMDD.HHMM
+    menu_label="${time:0:4}-${time:4:2}-${time:6:2} ${time:9:2}:${time:11:2}"
+fi
 syslinux_write <<EOF 4>"$USB_REAR_DIR/syslinux.cfg"
 label $HOSTNAME-$time
-    menu label ${time:0:4}-${time:4:2}-${time:6:2} ${time:9:2}:${time:11:2} $usb_label_workflow
+    menu label $menu_label $usb_label_workflow
     say $HOSTNAME-$time - Recover $HOSTNAME $usb_label_workflow ($time)
     text help
 Relax-and-Recover v$VERSION - $usb_label_workflow using kernel $(uname -r) ${IPADDR:+on $IPADDR}
@@ -116,7 +128,7 @@ ${BACKUP:+BACKUP=$BACKUP} ${OUTPUT:+OUTPUT=$OUTPUT} ${BACKUP_URL:+BACKUP_URL=$BA
     append initrd=/$USB_PREFIX/initrd.cgz root=/dev/ram0 vga=normal rw $KERNEL_CMDLINE
 
 label $HOSTNAME-$time
-    menu label ${time:0:4}-${time:4:2}-${time:6:2} ${time:9:2}:${time:11:2} $usb_label_workflow - AUTOMATIC RECOVER
+    menu label $menu_label $usb_label_workflow - AUTOMATIC RECOVER
     say $HOSTNAME-$time - Recover $HOSTNAME $usb_label_workflow ($time)
     text help
 Relax-and-Recover v$VERSION - $usb_label_workflow using kernel $(uname -r) ${IPADDR:+on $IPADDR}
@@ -128,25 +140,37 @@ ${BACKUP:+BACKUP=$BACKUP} ${OUTPUT:+OUTPUT=$OUTPUT} ${BACKUP_URL:+BACKUP_URL=$BA
 EOF
 
 # Clean up older images of a given system, but keep USB_RETAIN_BACKUP_NR
-# entries for backup and rescue
-backup_count=${USB_RETAIN_BACKUP_NR:-2}
-rescue_count=${USB_RETAIN_BACKUP_NR:-2}
-for rear_run in $(ls -dt $BUILD_DIR/outputfs/rear/$HOSTNAME/*); do
-    backup_name=$rear_run/${BACKUP_PROG_ARCHIVE}${BACKUP_PROG_SUFFIX}${BACKUP_PROG_COMPRESS_SUFFIX}
-    if [[ -e $backup_name ]] ; then
-        backup_count=$((backup_count - 1))
-        if (( backup_count < 0 )); then
-            Log "Remove older backup directory $rear_run"
-            rm -rf $v $rear_run >&8
-        fi
-    else
-        rescue_count=$((rescue_count - 1))
-        if (( rescue_count < 0 )); then
-            Log "Remove older rescue directory $rear_run"
-            rm -rf $v $rear_run >&8
+# entries for backup and rescue when backup on USB works in default mode.
+# When USB_SUFFIX is set the compliance mode is used where
+# backup on USB works in compliance with backup on NFS which means
+# a fixed backup directory and no automated removal of backups or other stuff
+# see https://github.com/rear/rear/issues/1164
+# Use plain $USB_SUFFIX and not "$USB_SUFFIX" because when USB_SUFFIX contains only blanks
+# test "$USB_SUFFIX" would result true because test " " results true:
+if ! test $USB_SUFFIX ; then
+    backup_count=${USB_RETAIN_BACKUP_NR:-2}
+    rescue_count=${USB_RETAIN_BACKUP_NR:-2}
+    for rear_run in $(ls -dt $BUILD_DIR/outputfs/rear/$HOSTNAME/*); do
+        # This fails when the backup archive name is not
+        # ${BACKUP_PROG_ARCHIVE}${BACKUP_PROG_SUFFIX}${BACKUP_PROG_COMPRESS_SUFFIX}
+        # so that in particular it would fail for incremental/differential backups
+        # but incremental/differential backups on USB require USB_SUFFIX to be set:
+        backup_name=$rear_run/${BACKUP_PROG_ARCHIVE}${BACKUP_PROG_SUFFIX}${BACKUP_PROG_COMPRESS_SUFFIX}
+        if [[ -e $backup_name ]] ; then
+            backup_count=$((backup_count - 1))
+            if (( backup_count < 0 )); then
+                Log "Remove older backup directory $rear_run"
+                rm -rf $v $rear_run >&8
+            fi
+        else
+            rescue_count=$((rescue_count - 1))
+            if (( rescue_count < 0 )); then
+                Log "Remove older rescue directory $rear_run"
+                rm -rf $v $rear_run >&8
+            fi
         fi
-    fi
-done
+    done
+fi
 
 # We generate a ReaR syslinux.cfg based on existing ReaR syslinux.cfg files.
 Log "Creating /rear/syslinux.cfg"
@@ -163,6 +187,9 @@ EOF
     # TODO: Sort systems by name, but also sort timestamps in reverse order
     for file in $(cd $BUILD_DIR/outputfs; find rear/*/* -name syslinux.cfg); do
         dir=$(dirname $file)
+        # FIXME: # type -a time
+        #        time is a shell keyword
+        #        time is /usr/bin/time
         time=$(basename $dir)
         system=$(basename $(dirname $dir))
 

usr/share/rear/prep/NETFS/default/070_set_backup_archive.sh

@@ -52,10 +52,15 @@ if ! test "NETFS" = "$BACKUP" -a "tar" = "$BACKUP_PROG" ; then
     Error "BACKUP_TYPE incremental or differential only works with BACKUP=NETFS and BACKUP_PROG=tar"
 fi
 # Incremental or differential backup is currently only known to work with BACKUP_URL=nfs://.
-# Other BACKUP_URL schemes may work but at least BACKUP_URL=usb:///... is known not to work
-# with incremental or differential backup (see https://github.com/rear/rear/issues/1145):
+# Other BACKUP_URL schemes may work and at least BACKUP_URL=usb:///... needs special setup
+# to work with incremental or differential backup (see https://github.com/rear/rear/issues/1145):
 if test "usb" = "$scheme" ; then
-    Error "BACKUP_TYPE incremental or differential does not work with BACKUP_URL=usb:///..."
+    # When USB_SUFFIX is set the compliance mode is used where
+    # backup on USB works in compliance with backup on NFS which means
+    # a fixed backup directory where incremental or differential backups work.
+    # Use plain $USB_SUFFIX and not "$USB_SUFFIX" because when USB_SUFFIX contains only blanks
+    # test "$USB_SUFFIX" would result true because test " " results true:
+    test $USB_SUFFIX || Error "BACKUP_TYPE incremental or differential requires USB_SUFFIX for BACKUP_URL=usb"
 fi
 # Incremental or differential backup and keeping old backup contradict each other (mutual exclusive)
 # so that NETFS_KEEP_OLD_BACKUP_COPY must not be 'true' in case of incremental or differential backup:

usr/share/rear/prep/USB/default/060_set_usb_device.sh

@@ -9,7 +9,24 @@ if [[ -z "$USB_DEVICE" ]] && [[ "$OUTPUT_URL" ]]; then
     esac
 fi
 
-USB_PREFIX="rear/$HOSTNAME/$(date +%Y%m%d.%H%M)"
+# Set USB_PREFIX:
+# Use plain $USB_SUFFIX and not "$USB_SUFFIX" because when USB_SUFFIX contains only blanks
+# test "$USB_SUFFIX" would result true because test " " results true:
+if test $USB_SUFFIX ; then
+    # When USB_SUFFIX is set the compliance mode is used which means
+    USB_PREFIX="rear/$HOSTNAME/$USB_SUFFIX"
+    # which results that backup on USB works in compliance with backup on NFS
+    # which means a fixed backup directory and no automated backups cleanup
+    # see https://github.com/rear/rear/issues/1164
+else
+    # When USB_SUFFIX is unset, empty, or contains only blanks
+    # the default mode for backup on USB is used which means
+    USB_PREFIX="rear/$HOSTNAME/$( date +%Y%m%d.%H%M )"
+    # which results multiple timestamp backup directories
+    # plus automated backups cleanup via USB_RETAIN_BACKUP_NR
+fi
+
+test "$USB_PREFIX" || USB_PREFIX="rear/$HOSTNAME/$(date +%Y%m%d.%H%M)"
 
 ### Change NETFS_PREFIX to USB_PREFIX if our backup URL is on USB
 if [[ "$BACKUP_URL" ]] ; then

usr/share/rear/verify/USB/NETFS/default/540_choose_backup_archive.sh

@@ -1,10 +1,27 @@
 
-scheme=$(url_scheme "$BACKUP_URL")
-if [[ "$scheme" != "usb" ]] ; then
-    return
-fi
+# In case of backup on USB let the user choose which backup will be restored.
 
-# Detect all backups on the USB device
+scheme=$( url_scheme "$BACKUP_URL" )
+# Skip if not backup on USB:
+test "usb" = "$scheme" || return
+
+# When USB_SUFFIX is set the compliance mode is used where
+# backup on USB works in compliance with backup on NFS which means
+# a fixed backup directory where the user cannot choose the backup
+# because what there is in the fixed backup directory will be restored
+# via RESTORE_ARCHIVES in usr/share/rear/prep/NETFS/default/070_set_backup_archive.sh
+# Use plain $USB_SUFFIX and not "$USB_SUFFIX" because when USB_SUFFIX contains only blanks
+# test "$USB_SUFFIX" would result true because test " " results true:
+test $USB_SUFFIX && return
+
+# Detect all backups on the USB device.
+# FIXME: This fails when the backup archive name is not
+# ${BACKUP_PROG_ARCHIVE}${BACKUP_PROG_SUFFIX}${BACKUP_PROG_COMPRESS_SUFFIX}
+# so that in particular it fails for incremental/differential backups
+# but incremental/differential backups usually require several backup archives
+# to be restored (one full backup plus one differential or several incremental backups)
+# cf. RESTORE_ARCHIVES in usr/share/rear/prep/NETFS/default/070_set_backup_archive.sh
+# and the code below only works for one single backup archive:
 backups=()
 backup_times=()
 for rear_run in $BUILD_DIR/outputfs/rear/$HOSTNAME/* ;do