support backup of single database or given databases

changes in localdump.sh ... and pgsql.sh (for first implementation) Other database types will follow

plugins/localdump/pgsql.sh

@@ -18,6 +18,7 @@
 # 2024-12-16  ah     v1.7  on snapshot mode it can fallback for single database to normal pg_dump of origin
 # 2024-12-17  ah     v1.8  handle env variables to disable snapshots or set times for disconnect
 # 2025-02-03  ah     v1.9  pg_dump in temp directory; dump file will be moved to backup dir
+# 2025-05-01  ah     v1.10 support backup of single database or given databases
 # ================================================================================
 
 if [ -z "$BACKUP_TARGETDIR" ]; then
@@ -38,6 +39,12 @@ fi
 # FUNCTION
 # --------------------------------------------------------------------------------
 
+# get a list of existing databases
+function pgsql.list(){
+  sSqlGetDblist="select datname from pg_database where not datistemplate and datallowconn order by datname;"
+  su ${PGUSER} -c "psql ${BACKUP_PARAMS} -At -c '$sSqlGetDblist' postgres" 2>/dev/null | grep -v "^$snapshotprefix"
+}
+
 # backup all databases
 function pgsql.backup(){
 
@@ -77,7 +84,7 @@ function pgsql.backup(){
     bUseSnapshot=0
   else
     # Detect a readonly or writeable postgres host.
-    TESTDB="imlbackup_createtest"
+    TESTDB="imlbackup_createtest_${snapshotprefix}"
     su ${PGUSER} -c "dropdb ${TESTDB}" >/dev/null 2>&1
     if su ${PGUSER} -c "psql ${BACKUP_PARAMS} -c \"CREATE DATABASE ${TESTDB};\"" >/dev/null 2>&1
     then
@@ -99,8 +106,14 @@ function pgsql.backup(){
     fi
   fi
 
-  sSqlGetDblist="select datname from pg_database where not datistemplate and datallowconn order by datname;"
-  for DATABASE in $( su ${PGUSER} -c "psql ${BACKUP_PARAMS} -At -c '$sSqlGetDblist' postgres" 2>/dev/null | grep -v "^$snapshotprefix" )
+  sDBList="$*"
+  if [ -z "$sDBList" ]; then 
+    sDBList="$( pgsql.list )"
+    echo "INFO: found databases:" 
+    sed "s#^#      - #g" <<< "$sDBList"
+  fi
+
+  for DATABASE in $sDBList
   do
     echo -n "__DB__${SERVICENAME} backup $DATABASE ... "