diff --git a/bookeeper/__main__.py b/bookeeper/__main__.py
index 9ef4a81..144a1a8 100644
--- a/bookeeper/__main__.py
+++ b/bookeeper/__main__.py
@@ -3,73 +3,51 @@ import sqlite3
 import sys
 
 from . import args
-from . import calc
 from . import db
 from . import parser
 from . import util
 
+from .ctx import Context
+
+
+dbconn = None
+dbcur  = None
+ctx    = None
 
 try:
+  parg = args.create()
   try:  # parsing args
-    params = args.parse(sys.argv[1:])
+    params = parg.parse_args(sys.argv[1:])
+    if params.actions is None:
+      params.actions = []
   except Exception as e:
-    args.print_help()
+    parg.print_help()
     raise Exception("failure while parsing args", e)
 
   try:  # initializing DB
     dbconn = sqlite3.connect(params.dbpath)
     dbcur  = dbconn.cursor()
     db.try_init(dbcur)
-    dbcur.execute("BEGIN;")
   except Exception as e:
     raise Exception("failure while initializing DB", e)
 
-  if not sys.stdin.isatty():
-    try:  # insert new records
-      for tx in parser.parse(sys.stdin):
-        db.apply(dbcur, tx)
+  ctx = Context(dbcur)
+  for action in enumerate(params.actions):
+    try:
+      action[1](ctx)
     except Exception as e:
-      raise Exception("failure while inserting new records", e)
-
-  try:  # writing outputs
-    calc.call(
-      calc.balancesheet,
-      params.balancesheet,
-      dbcur,
-    )
-    calc.call(
-      calc.plstatement,
-      util.get_or(params.plstatement, 0),
-      dbcur,
-      begin=util.get_or(params.plstatement, 1),
-      end  =util.get_or(params.plstatement, 2),
-    )
-    calc.call(
-      calc.balancetransition,
-      params.balancetransition,
-      dbcur,
-    )
-    calc.call(
-      calc.pltransition,
-      util.get_or(params.pltransition, 0),
-      dbcur,
-      datefmt=util.get_or(params.pltransition, 1),
-    )
-  except Exception as e:
-    raise Exception("failure while calculating output", e)
+      raise Exception(f"failure while executing {action[0]}-th action", e)
 
 except Exception as e:
   print(f"bookeeper: error: {e}", file=sys.stderr)
-  dbcur and dbcur.execute("ROLLBACK;")
-else:
-  if params.permanentize:
-    dbcur.execute("COMMIT;")
-  else:
-    dbcur.execute("ROLLBACK;")
 
 finally:
+  if ctx:
+    ctx.finalize()
+
   if dbcur:
     dbcur.close()
+
   if dbconn:
     dbconn.commit();
     dbconn.close()
diff --git a/bookeeper/args.py b/bookeeper/args.py
index 10571c0..94089d6 100644
--- a/bookeeper/args.py
+++ b/bookeeper/args.py
@@ -1,55 +1,68 @@
 import argparse
 
-_parser = argparse.ArgumentParser(
-  prog="bookeeper",
-  description="CLI app for bookkeeping",
-  epilog="developed by falsycat <me@falsy.cat>",
-)
+def create():
+  p = argparse.ArgumentParser(
+    prog="bookeeper",
+    description="CLI app for bookkeeping",
+    epilog="developed by falsycat <me@falsy.cat>",
+  )
 
-_parser.add_argument(
-  "dbpath",
-  help="path to sqlite database file",
-  nargs="?",
-  default=":memory:",
-)
+  p.add_argument(
+    "dbpath",
+    help="path to sqlite database file",
+    nargs="?",
+    default=":memory:",
+  )
 
-_parser.add_argument(
-  "-p", "--permanentize",
-  help="apply changes",
-  action="store_true",
-  dest="permanentize",
-)
+  p.add_argument(
+    "-p", "--permanentize",
+    help="apply changes",
+    nargs=1,
+    action=_PermanentizeAction,
+    dest="actions",
+  )
+  p.add_argument(
+    "-r", "--read",
+    help="reads all records from the file",
+    nargs=1,
+    action=_ReadRecordsAction,
+    dest="actions",
+  )
+  p.add_argument(
+    "-o", "--output",
+    help="changes output file for latter actions",
+    nargs=1,
+    action=_ChangeOutputAction,
+    dest="actions",
+  )
+  p.add_argument(
+    "--sql",
+    help="executes SQL command",
+    nargs=1,
+    action=_SqlAction,
+    dest="actions",
+  )
+  return p
 
-_parser.add_argument(
-  "-bs", "--balancesheet",
-  help="emit balancesheet",
-  action="store",
-  dest="balancesheet",
-)
-_parser.add_argument(
-  "-bt", "--balance-transition",
-  help="emit daily transition of balance",
-  action="store",
-  dest="balancetransition",
-)
-_parser.add_argument(
-  "-pl", "--pl-statement",
-  help="emit P/L statement (filepath, begin, end)",
-  action="store",
-  nargs="+",
-  dest="plstatement",
-)
-_parser.add_argument(
-  "-plt", "--pl-transition",
-  help="emit transition of P/L",
-  action="store",
-  nargs="+",
-  dest="pltransition",
-)
+class _PermanentizeAction(argparse.Action):
+  def __call__(self, parser, ns, values, option_string=None):
+    _push_action(ns, lambda x: x.permanentize())
 
-def print_help():
-  _parser.print_help()
+class _ReadRecordsAction(argparse.Action):
+  def __call__(self, parser, ns, values, option_string=None):
+    _push_action(ns, lambda x: x.read_records(values[0]))
 
-def parse(args):
-  ret = _parser.parse_args(args)
-  return ret
+class _ChangeOutputAction(argparse.Action):
+  def __call__(self, parser, ns, values, option_string=None):
+    _push_action(ns, lambda x: x.change_output(values[0]))
+
+class _SqlAction(argparse.Action):
+  def __call__(self, parser, ns, values, option_string=None):
+    _push_action(ns, lambda x: x.sql(values[0]))
+
+def _push_action(ns, act):
+  actions = getattr(ns, "actions", None)
+  if actions is None:
+    actions = []
+    setattr(ns, "actions", actions)
+  actions.append(act)
diff --git a/bookeeper/calc.py b/bookeeper/calc.py
deleted file mode 100644
index 30ea070..0000000
--- a/bookeeper/calc.py
+++ /dev/null
@@ -1,101 +0,0 @@
-import sys
-
-def call(func, path, *args, **kwargs):
-  if path == "-":
-    func(sys.stdout, *args, **kwargs)
-  elif path is None:
-    pass
-  else:
-    with open(path, "w") as f:
-      func(f, *args, **kwargs)
-
-def balancesheet(stream, cur):
-  cur.execute("""
-    SELECT
-      entry.type,
-      entry.name,
-      SUM(journal.amount)
-    FROM journal RIGHT JOIN entry ON journal.entry=entry.id
-    WHERE entry.type in ("A","D","N")
-    GROUP BY entry.name;
-  """)
-  for row in cur:
-    print(_recover_entry_name(row[0], row[1]), row[2], file=stream, sep=",")
-
-def plstatement(stream, cur, begin=None, end=None):
-  if begin is None:
-    begin = "0000-00-00";
-  if end is None:
-    end = "9999-12-31";
-
-  cur.execute("""
-    SELECT
-      entry.type,
-      entry.name,
-      SUM(journal.amount)
-    FROM journal
-      RIGHT JOIN entry ON journal.entry=entry.id
-      RIGHT JOIN tx    ON journal.tx   =tx.id
-    WHERE
-      entry.type in ("E","R") AND tx.date BETWEEN ? AND ?
-    GROUP BY entry.name;
-  """, (begin, end))
-  for row in cur:
-    print(_recover_entry_name(row[0], row[1]), row[2], file=stream, sep=",")
-
-def balancetransition(stream, cur):
-  cur.execute("""
-    SELECT
-      date,
-      SUM(sum)
-        OVER(ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
-    FROM (
-      SELECT
-        tx.date AS date,
-        SUM(
-          CASE WHEN entry.type="A" THEN journal.amount ELSE -journal.amount END
-        ) AS sum
-      FROM journal
-        RIGHT JOIN entry ON journal.entry=entry.id
-        RIGHT JOIN tx    ON journal.tx   =tx.id
-      WHERE    entry.type in ("A","D","N")
-      GROUP BY tx.date
-    );
-  """)
-  for row in cur:
-    print(*row, file=stream, sep=",")
-
-def pltransition(stream, cur, datefmt=None):
-  if datefmt is None:
-    datefmt = "%Y-%m-%d"
-  cur.execute("""
-    WITH temp AS (
-        SELECT
-          STRFTIME(?, tx.date) AS period,
-          entry.type           AS type,
-          SUM(amount)          AS sum
-        FROM journal
-          RIGHT JOIN entry ON journal.entry=entry.id
-          RIGHT JOIN tx    ON journal.tx   =tx.id
-        WHERE    entry.type in ("E","R")
-        GROUP BY period, entry.type
-      )
-    SELECT
-      a.period AS period,
-      a.sum    AS expense,
-      IFNULL(b.sum, 0) AS revenue
-    FROM temp AS a LEFT JOIN temp AS b ON a.period=b.period AND b.type="R"
-    WHERE a.type="E";
-  """, [datefmt])
-  for row in cur:
-    print(*row, file=stream, sep=",")
-
-def _recover_entry_name(t: str, name: str):
-  m = {
-    "A": "asset",
-    "D": "debt",
-    "N": "net",
-    "E": "expense",
-    "R": "revenue",
-  }
-  return f"{m[t]}/{name}"
diff --git a/bookeeper/ctx.py b/bookeeper/ctx.py
new file mode 100644
index 0000000..8f5675f
--- /dev/null
+++ b/bookeeper/ctx.py
@@ -0,0 +1,46 @@
+import io
+import sqlite3
+import sys
+
+from . import db
+from . import parser
+
+class Context:
+  def __init__(self, dbcur: sqlite3.Cursor):
+    self.ostream = sys.stdout
+    self.dbcur   = dbcur
+    self.dbcur.execute("BEGIN;")
+
+  def finalize(self):
+    self.dbcur.execute("ROLLBACK;")
+    self.close_output()
+
+  def permanentize(self):
+    self.dbcur.execute("COMMIT;")
+    self.dbcur.execute("BEGIN;")
+
+  def read_records(self, path):
+    def parse(st):
+      for tx in parser.parse(st):
+        db.apply(self.dbcur, tx)
+
+    if path == "-":
+      parse(sys.stdin)
+    else:
+      with open(path) as f:
+        parse(f)
+
+  def change_output(self, path):
+    self.close_output()
+    if path != "-":
+      self.ostream = open(path, "w")
+
+  def close_output(self):
+    if self.ostream is not sys.stdout:
+      self.ostream.close()
+    self.ostream = sys.stdout
+
+  def sql(self, cmd: str):
+    self.dbcur.execute(cmd)
+    for row in self.dbcur:
+      print(*row, file=self.ostream)
diff --git a/bookeeper/util.py b/bookeeper/util.py
deleted file mode 100644
index 2037e4d..0000000
--- a/bookeeper/util.py
+++ /dev/null
@@ -1,5 +0,0 @@
-def get_or(a: list, idx: int, default = None):
-  try:
-    return a[idx]
-  except:
-    return default