Add a new backup script

backup-tar/backup.sh

+#!/usr/bin/env bash
+
+set -e
+
+fail() {
+    echo "$1" >&2
+    exit 1
+}
+
+[[ "$1" = "full" ]] || [[ "$1" = "weekly" ]] || [[ "$1" = "daily" ]] || \
+    fail "usage: $0 [full|weekly|daily]"
+
+TARGET=backup-$HOSTNAME@antea
+LOCAL_HOME_ID=$(stat -c %d /home)
+SOURCES=$(comm -12 <(getent passwd | cut -d: -f6 | sort) <(for i in /home/*; do [[ $(stat -c %d $i) -eq $LOCAL_HOME_ID ]] && echo $i; done))
+TYPE=$1
+TIMESTAMP=$(date +"%Y-%m-%d")
+
+BACKUP_FILE=${TYPE}/${TIMESTAMP}.tar.xz
+INCFILE_TGT=${TYPE}/${TIMESTAMP}.snar
+INCFILE=${TIMESTAMP}.${TYPE}.snar
+
+INC_FILTER="."
+if [[ "$TYPE" = "weekly" ]]; then
+    INCFILE='\(full\|weekly\)'
+fi
+
+[[ -f $INCFILE ]] && fail "ERROR: backup already in progress (incremental backup file exists)"
+if [[ "$TYPE" != "full" ]]; then
+    LAST=$(ls *.snar | sort | grep $INC_FILTER | tail -n1)
+    if [[ -f "$LAST" ]]; then
+        cp --reflink=auto $LAST $INCFILE
+    fi
+fi
+
+set -x
+
+ssh $TARGET "mkdir -p $TYPE"
+tar --create --xz --xattrs --acls --listed-incremental=$INCFILE $SOURCES | ssh $TARGET "cat > $BACKUP_FILE"
+scp $INCFILE $TARGET:$INCFILE_TGT

backup-tar/init.sh

+#!/usr/bin/env bash
+set -ex
+KEY=$HOME/.ssh/id_rsa
+PUB=${KEY}.pub
+
+test -f $KEY && exit 1
+ssh-keygen -b 4096 -t rsa -N "" -f $KEY
+echo "Add the following to /backup-tar/$HOSTNAME/.ssh/authorized_keys on the backup server:"
+cat $PUB