diff --git a/bin/cylc-cat-log b/bin/cylc-cat-log
index 3f9332f3088..c3cc3c535d6 100755
--- a/bin/cylc-cat-log
+++ b/bin/cylc-cat-log
@@ -53,15 +53,20 @@ import shlex
 from glob import glob
 from shlex import quote
 from stat import S_IRUSR
-from tempfile import mkstemp
+from tempfile import NamedTemporaryFile
 from subprocess import Popen, PIPE
 
+from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.exceptions import UserInputError
 import cylc.flow.flags
+from cylc.flow.hostuserutil import is_remote
 from cylc.flow.option_parsers import CylcOptionParser as COP
+from cylc.flow.pathutil import (
+    get_remote_suite_run_job_dir,
+    get_suite_run_job_dir,
+    get_suite_run_log_name,
+    get_suite_run_pub_db_name)
 from cylc.flow.rundb import CylcSuiteDAO
-from cylc.flow.hostuserutil import is_remote
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.task_id import TaskID
 from cylc.flow.task_job_logs import (
     JOB_LOG_OUT, JOB_LOG_ERR, JOB_LOG_OPTS, NN, JOB_LOGS_LOCAL)
@@ -149,14 +154,14 @@ def view_log(logpath, mode, tailer_tmpl, batchview_cmd=None, remote=False):
     elif not remote and mode == 'edit':
         # Copy the log to a temporary read-only file for viewing in editor.
         # Copy only BUFSIZE bytes at time, in case the file is huge.
-        outfile = mkstemp(dir=glbl_cfg().get_tmpdir())[1]
+        outfile = NamedTemporaryFile()
         with open(logpath, 'rb') as log:
-            with open(outfile, 'wb') as out:
+            data = log.read(BUFSIZE)
+            while data:
+                outfile.write(data)
                 data = log.read(BUFSIZE)
-                while data:
-                    out.write(data)
-                    data = log.read(BUFSIZE)
-        os.chmod(outfile, S_IRUSR)
+        os.chmod(outfile.name, S_IRUSR)
+        outfile.seek(0, 0)
         return outfile
     elif mode == 'cat' or (remote and mode == 'edit'):
         # Just cat file contents to stdout.
@@ -234,11 +239,7 @@ def get_task_job_attrs(suite_name, point, task, submit_num):
 
     """
     suite_dao = CylcSuiteDAO(
-        os.path.join(
-            glbl_cfg().get_derived_host_item(
-                suite_name, "suite run directory"),
-            "log", CylcSuiteDAO.DB_FILE_BASE_NAME),
-        is_public=True)
+        get_suite_run_pub_db_name(suite_name), is_public=True)
     task_job_data = suite_dao.select_task_job(point, task, submit_num)
     suite_dao.close()
     if task_job_data is None:
@@ -264,17 +265,17 @@ def tmpfile_edit(tmpfile, geditor=False):
         editor = glbl_cfg().get(['editors', 'gui'])
     else:
         editor = glbl_cfg().get(['editors', 'terminal'])
-    modtime1 = os.stat(tmpfile).st_mtime
+    modtime1 = os.stat(tmpfile.name).st_mtime
     cmd = shlex.split(editor)
-    cmd.append(tmpfile)
+    cmd.append(tmpfile.name)
     proc = Popen(cmd, stderr=PIPE)
     err = proc.communicate()[1].decode()
     ret_code = proc.wait()
     if ret_code == 0:
-        if os.stat(tmpfile).st_mtime > modtime1:
+        if os.stat(tmpfile.name).st_mtime > modtime1:
             sys.stderr.write(
                 'WARNING: you edited a TEMPORARY COPY of %s\n' % (
-                    os.path.basename(tmpfile)))
+                    os.path.basename(tmpfile.name)))
     if ret_code and err:
         sys.stderr.write(err)
 
@@ -317,7 +318,7 @@ def main():
 
     if len(args) == 1:
         # Cat suite logs, local only.
-        logpath = glbl_cfg().get_derived_host_item(suite_name, "suite log")
+        logpath = get_suite_run_log_name(suite_name)
         if options.rotation_num:
             logs = glob('%s.*' % logpath)
             logs.sort(key=os.path.getmtime, reverse=True)
@@ -392,10 +393,9 @@ def main():
         log_is_retrieved = (glbl_cfg().get_host_item('retrieve job logs', host)
                             and live_job_id is None)
         if log_is_remote and (not log_is_retrieved or options.force_remote):
-            logpath = os.path.normpath(os.path.join(
-                glbl_cfg().get_derived_host_item(
-                    suite_name, "suite job log directory", host, user),
-                point, task, options.submit_num, options.filename))
+            logpath = os.path.normpath(get_remote_suite_run_job_dir(
+                host, user,
+                suite_name, point, task, options.submit_num, options.filename))
             tail_tmpl = str(glbl_cfg().get_host_item(
                 "tail command template", host, user))
             # Reinvoke the cat-log command on the remote account.
@@ -407,31 +407,29 @@ def main():
             if batchview_cmd:
                 cmd.append('--remote-arg=%s' % quote(batchview_cmd))
             cmd.append(suite_name)
-            capture = (mode == 'edit')
+            is_edit_mode = (mode == 'edit')
             try:
                 proc = remote_cylc_cmd(
-                    cmd, user, host, capture_process=capture,
+                    cmd, user, host, capture_process=is_edit_mode,
                     manage=(mode == 'tail'))
             except KeyboardInterrupt:
                 # Ctrl-C while tailing.
                 pass
             else:
-                if capture:
+                if is_edit_mode:
                     # Write remote stdout to a temp file for viewing in editor.
                     # Only BUFSIZE bytes at a time in case huge stdout volume.
-                    out = mkstemp(dir=glbl_cfg().get_tmpdir())[1]
-                    with open(out, 'wb') as outf:
+                    out = NamedTemporaryFile()
+                    data = proc.stdout.read(BUFSIZE)
+                    while data:
+                        out.write(data)
                         data = proc.stdout.read(BUFSIZE)
-                        while data:
-                            outf.write(data)
-                            data = proc.stdout.read(BUFSIZE)
-                    os.chmod(out, S_IRUSR)
+                    os.chmod(out.name, S_IRUSR)
+                    out.seek(0, 0)
         else:
             # Local task job or local job log.
-            logpath = os.path.normpath(os.path.join(
-                glbl_cfg().get_derived_host_item(
-                    suite_name, "suite job log directory"),
-                point, task, options.submit_num, options.filename))
+            logpath = os.path.normpath(get_suite_run_job_dir(
+                suite_name, point, task, options.submit_num, options.filename))
             tail_tmpl = str(glbl_cfg().get_host_item("tail command template"))
             out = view_log(logpath, mode, tail_tmpl, batchview_cmd)
             if mode != 'edit':
diff --git a/bin/cylc-ls-checkpoints b/bin/cylc-ls-checkpoints
index 1562f6fcc4f..03fd85c26aa 100755
--- a/bin/cylc-ls-checkpoints
+++ b/bin/cylc-ls-checkpoints
@@ -30,8 +30,8 @@ if remrun():
 
 import os
 
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.option_parsers import CylcOptionParser as COP
+from cylc.flow.pathutil import get_suite_run_pub_db_name
 from cylc.flow.rundb import CylcSuiteDAO
 from cylc.flow.terminal import cli_function
 
@@ -98,12 +98,7 @@ def list_checkpoints(suite, callback):
 
 def _get_dao(suite):
     """Return the DAO (public) for suite."""
-
-    suite_log_dir = glbl_cfg().get_derived_host_item(
-        suite, 'suite log directory')
-    pub_db_path = os.path.join(os.path.dirname(suite_log_dir),
-                               CylcSuiteDAO.DB_FILE_BASE_NAME)
-    return CylcSuiteDAO(pub_db_path, is_public=True)
+    return CylcSuiteDAO(get_suite_run_pub_db_name(suite), is_public=True)
 
 
 def _write_row(title, row_idx, row):
diff --git a/bin/cylc-report-timings b/bin/cylc-report-timings
index 2653cff3c75..eaccbc02e55 100755
--- a/bin/cylc-report-timings
+++ b/bin/cylc-report-timings
@@ -58,8 +58,8 @@ import contextlib
 import os
 
 from cylc.flow.exceptions import CylcError
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.option_parsers import CylcOptionParser as COP
+from cylc.flow.pathutil import get_suite_run_pub_db_name
 from cylc.flow.rundb import CylcSuiteDAO
 from cylc.flow.terminal import cli_function
 
@@ -160,14 +160,7 @@ def format_rows(header, rows):
 
 def _get_dao(suite):
     """Return the DAO (public) for suite."""
-    suite_log_dir = glbl_cfg().get_derived_host_item(
-        suite, 'suite log directory'
-    )
-    pub_db_path = os.path.join(
-        os.path.dirname(suite_log_dir),
-        CylcSuiteDAO.DB_FILE_BASE_NAME
-    )
-    return CylcSuiteDAO(pub_db_path, is_public=True)
+    return CylcSuiteDAO(get_suite_run_pub_db_name(suite), is_public=True)
 
 
 class TimingSummary(object):
diff --git a/bin/cylc-submit b/bin/cylc-submit
index 443aa8e99e3..b798b1b0b85 100755
--- a/bin/cylc-submit
+++ b/bin/cylc-submit
@@ -39,13 +39,13 @@ import os
 from time import sleep
 
 from cylc.flow import LOG
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.config import SuiteConfig
 from cylc.flow.cycling.loader import get_point
 from cylc.flow.exceptions import UserInputError
 import cylc.flow.flags
 from cylc.flow.subprocpool import SubProcPool
 from cylc.flow.option_parsers import CylcOptionParser as COP
+from cylc.flow.pathutil import make_suite_run_tree
 from cylc.flow.suite_db_mgr import SuiteDatabaseManager
 from cylc.flow.broadcast_mgr import BroadcastMgr
 from cylc.flow.suite_srv_files_mgr import SuiteSrvFilesManager
@@ -106,7 +106,7 @@ def main():
                 taskdef, get_point(point_str).standardise(), is_startup=True))
 
     # Initialise job submit environment
-    glbl_cfg().create_cylc_run_tree(suite)
+    make_suite_run_tree(suite)
     pool = SubProcPool()
     db_mgr = SuiteDatabaseManager()
     task_job_mgr = TaskJobManager(
diff --git a/bin/cylc-view b/bin/cylc-view
index 2f5da7eaad1..63175785b9d 100755
--- a/bin/cylc-view
+++ b/bin/cylc-view
@@ -42,10 +42,10 @@ from subprocess import call
 
 from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.option_parsers import CylcOptionParser as COP
+from cylc.flow.parsec.fileparse import read_and_proc
 from cylc.flow.suite_srv_files_mgr import SuiteSrvFilesManager
 from cylc.flow.templatevars import load_template_vars
 from cylc.flow.terminal import cli_function
-from cylc.flow.parsec.fileparse import read_and_proc
 
 
 def parse_args():
@@ -119,7 +119,6 @@ def main():
     options, args = parse_args()
     suite, suiterc = SuiteSrvFilesManager().parse_suite_arg(options, args[0])
 
-    cylc_tmpdir = glbl_cfg().get_tmpdir()
     if options.geditor:
         editor = glbl_cfg().get(['editors', 'gui'])
     else:
@@ -148,7 +147,6 @@ def main():
     # write to a temporary file
     viewfile = NamedTemporaryFile(
         suffix=".suite.rc", prefix=suite.replace('/', '_') + '.',
-        dir=cylc_tmpdir
     )
     for line in lines:
         viewfile.write((line + '\n').encode())
diff --git a/cylc/flow/cfgspec/globalcfg.py b/cylc/flow/cfgspec/globalcfg.py
index 0ecb5236a2b..c8157cacab9 100644
--- a/cylc/flow/cfgspec/globalcfg.py
+++ b/cylc/flow/cfgspec/globalcfg.py
@@ -17,15 +17,11 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 """Cylc site and user configuration file spec."""
 
-import atexit
 import os
 import re
-import shutil
-from tempfile import mkdtemp
 
 from cylc.flow import LOG
 from cylc.flow import __version__ as CYLC_VERSION
-from cylc.flow.exceptions import GlobalConfigError
 from cylc.flow.hostuserutil import get_user_home, is_remote_user
 from cylc.flow.network import Priv
 from cylc.flow.parsec.config import ParsecConfig
@@ -41,21 +37,21 @@
 # - default: the default value (optional).
 # - allowed_2, ...: the only other allowed values of this setting (optional).
 SPEC = {
+    # suite
     'process pool size': [VDR.V_INTEGER, 4],
     'process pool timeout': [VDR.V_INTERVAL, DurationFloat(600)],
-    'temporary directory': [VDR.V_STRING],
-    'state dump rolling archive length': [VDR.V_INTEGER, 10],
+    # client
     'disable interactive command prompts': [VDR.V_BOOLEAN, True],
-    'enable run directory housekeeping': [VDR.V_BOOLEAN],
-    'run directory rolling archive length': [VDR.V_INTEGER, 2],
-    'task host select command timeout': [VDR.V_INTERVAL, DurationFloat(10)],
-    'xtrigger function timeout': [VDR.V_INTERVAL, DurationFloat(10)],
+    # suite
+    'run directory rolling archive length': [VDR.V_INTEGER, -1],
+    # suite-task communication
     'task messaging': {
         'retry interval': [VDR.V_INTERVAL, DurationFloat(5)],
         'maximum number of tries': [VDR.V_INTEGER, 7],
         'connection timeout': [VDR.V_INTERVAL, DurationFloat(30)],
     },
 
+    # suite
     'cylc': {
         'UTC mode': [VDR.V_BOOLEAN],
         'health check interval': [VDR.V_INTERVAL, DurationFloat(600)],
@@ -82,11 +78,13 @@
         },
     },
 
+    # suite
     'suite logging': {
         'rolling archive length': [VDR.V_INTEGER, 5],
         'maximum size in bytes': [VDR.V_INTEGER, 1000000],
     },
 
+    # general
     'documentation': {
         'local': [VDR.V_STRING, ''],
         'online': [VDR.V_STRING,
@@ -94,19 +92,23 @@
         'cylc homepage': [VDR.V_STRING, 'http://cylc.github.io/'],
     },
 
+    # general
     'document viewers': {
         'html': [VDR.V_STRING, 'firefox'],
     },
 
+    # client
     'editors': {
         'terminal': [VDR.V_STRING, 'vim'],
         'gui': [VDR.V_STRING, 'gvim -f'],
     },
 
+    # client
     'monitor': {
         'sort order': [VDR.V_STRING, 'definition', 'alphanumeric'],
     },
 
+    # task
     'hosts': {
         'localhost': {
             'run directory': [VDR.V_STRING, '$HOME/cylc-run'],
@@ -175,6 +177,7 @@
         },
     },
 
+    # task
     'task events': {
         'execution timeout': [VDR.V_INTERVAL],
         'handlers': [VDR.V_STRING_LIST],
@@ -188,6 +191,7 @@
         'submission timeout': [VDR.V_INTERVAL],
     },
 
+    # client
     'test battery': {
         'remote host with shared fs': [VDR.V_STRING],
         'remote host': [VDR.V_STRING],
@@ -204,12 +208,14 @@
         },
     },
 
+    # suite
     'suite host self-identification': {
         'method': [VDR.V_STRING, 'name', 'address', 'hardwired'],
         'target': [VDR.V_STRING, 'google.com'],
         'host': [VDR.V_STRING],
     },
 
+    # suite
     'authentication': {
         # Allow owners to grant public shutdown rights at the most, not full
         # control.
@@ -220,6 +226,7 @@
                 Priv.STATE_TOTALS, Priv.READ, Priv.SHUTDOWN]])
     },
 
+    # suite
     'suite servers': {
         'run hosts': [VDR.V_SPACELESS_STRING_LIST],
         'run ports': [VDR.V_INTEGER_LIST, list(range(43001, 43101))],
@@ -258,6 +265,10 @@ def upg(cfg, descr):
     u.obsolete('8.0.0', ['suite servers', 'scan hosts'])
     u.obsolete('8.0.0', ['suite servers', 'scan ports'])
     u.obsolete('8.0.0', ['communication'])
+    u.obsolete('8.0.0', ['temporary directory'])
+    u.obsolete('8.0.0', ['task host select command timeout'])
+    u.obsolete('8.0.0', ['xtrigger function timeout'])
+    u.obsolete('8.0.0', ['enable run directory housekeeping'])
 
     u.upgrade()
 
@@ -266,9 +277,6 @@ class GlobalConfig(ParsecConfig):
     """
     Handle global (all suites) site and user configuration for cylc.
     User file values override site file values.
-
-    For all derived items - paths hardwired under the configurable top
-    levels - use the get_derived_host_item(suite,host) method.
     """
 
     _DEFAULT = None
@@ -328,49 +336,7 @@ def load(self):
                         LOG.error('bad %s %s', conf_type, fname)
                         raise
         # (OK if no flow.rc is found, just use system defaults).
-        self.transform()
-
-    def get_derived_host_item(
-            self, suite, item, host=None, owner=None, replace_home=False):
-        """Compute hardwired paths relative to the configurable top dirs."""
-
-        # suite run dir
-        srdir = os.path.join(
-            self.get_host_item('run directory', host, owner, replace_home),
-            suite)
-        # suite workspace
-        swdir = os.path.join(
-            self.get_host_item('work directory', host, owner, replace_home),
-            suite)
-
-        if item == 'suite run directory':
-            value = srdir
-
-        elif item == 'suite log directory':
-            value = os.path.join(srdir, 'log', 'suite')
-
-        elif item == 'suite log':
-            value = os.path.join(srdir, 'log', 'suite', 'log')
-
-        elif item == 'suite job log directory':
-            value = os.path.join(srdir, 'log', 'job')
-
-        elif item == 'suite config log directory':
-            value = os.path.join(srdir, 'log', 'suiterc')
-
-        elif item == 'suite work root':
-            value = swdir
-
-        elif item == 'suite work directory':
-            value = os.path.join(swdir, 'work')
-
-        elif item == 'suite share directory':
-            value = os.path.join(swdir, 'share')
-
-        else:
-            raise GlobalConfigError("Illegal derived item: " + item)
-
-        return value
+        self._transform()
 
     def get_host_item(self, item, host=None, owner=None, replace_home=False,
                       owner_home=None):
@@ -420,85 +386,7 @@ def get_host_item(self, item, host=None, owner=None, replace_home=False,
             value = 'zmq'
         return value
 
-    def roll_directory(self, dir_, name, archlen=0):
-        """Create a directory after rolling back any previous instances of it.
-
-        E.g. if archlen = 2 we keep:
-            dir_, dir_.1, dir_.2. If 0 keep no old ones.
-        """
-        for i in range(archlen, -1, -1):  # archlen...0
-            if i > 0:
-                dpath = dir_ + '.' + str(i)
-            else:
-                dpath = dir_
-            if os.path.exists(dpath):
-                if i >= archlen:
-                    # remove oldest backup
-                    shutil.rmtree(dpath)
-                else:
-                    # roll others over
-                    os.rename(dpath, dir_ + '.' + str(i + 1))
-        self.create_directory(dir_, name)
-
-    @staticmethod
-    def create_directory(dir_, name):
-        """Create directory. Raise GlobalConfigError on error."""
-        try:
-            os.makedirs(dir_, exist_ok=True)
-        except OSError as exc:
-            LOG.exception(exc)
-            raise GlobalConfigError(
-                'Failed to create directory "' + name + '"')
-
-    def create_cylc_run_tree(self, suite):
-        """Create all top-level cylc-run output dirs on the suite host."""
-        cfg = self.get()
-        item = 'suite run directory'
-        idir = self.get_derived_host_item(suite, item)
-        LOG.debug('creating %s: %s', item, idir)
-        if cfg['enable run directory housekeeping']:
-            self.roll_directory(
-                idir, item, cfg['run directory rolling archive length'])
-
-        for item in [
-                'suite log directory',
-                'suite job log directory',
-                'suite config log directory',
-                'suite work directory',
-                'suite share directory']:
-            idir = self.get_derived_host_item(suite, item)
-            LOG.debug('creating %s: %s', item, idir)
-            self.create_directory(idir, item)
-
-        item = 'temporary directory'
-        value = cfg[item]
-        if value:
-            self.create_directory(value, item)
-
-    def get_tmpdir(self):
-        """Make a new temporary directory and arrange for it to be
-        deleted automatically when we're finished with it. Call this
-        explicitly just before use to ensure the directory is not
-        deleted by other processes before it is needed. THIS IS
-        CURRENTLY ONLY USED BY A FEW CYLC COMMANDS. If cylc suites
-        ever need it this must be called AFTER FORKING TO DAEMON MODE or
-        atexit() will delete the directory when the initial process
-        exits after forking."""
-
-        cfg = self.get()
-        tdir = cfg['temporary directory']
-        if tdir:
-            tdir = os.path.expandvars(tdir)
-            tmpdir = mkdtemp(prefix="cylc-", dir=os.path.expandvars(tdir))
-        else:
-            tmpdir = mkdtemp(prefix="cylc-")
-        # self-cleanup
-        atexit.register(lambda: shutil.rmtree(tmpdir))
-        # now replace the original item to allow direct access
-        cfg['temporary directory'] = tmpdir
-        return tmpdir
-
-    def transform(self):
+    def _transform(self):
         """Transform various settings.
 
         Host item values of None default to modified localhost values.
diff --git a/cylc/flow/config.py b/cylc/flow/config.py
index 6e7d181d6fa..0a92554623f 100644
--- a/cylc/flow/config.py
+++ b/cylc/flow/config.py
@@ -56,6 +56,12 @@
 from cylc.flow.cycling.iso8601 import ingest_time
 import cylc.flow.flags
 from cylc.flow.graphnode import GraphNodeParser
+from cylc.flow.pathutil import (
+    get_suite_run_dir,
+    get_suite_run_log_dir,
+    get_suite_run_share_dir,
+    get_suite_run_work_dir,
+)
 from cylc.flow.print_tree import print_tree
 from cylc.flow.subprocctx import SubFuncContext
 from cylc.flow.subprocpool import get_func
@@ -119,14 +125,10 @@ def __init__(self, suite, fpath, template_vars=None,
         self.suite = suite  # suite name
         self.fpath = fpath  # suite definition
         self.fdir = os.path.dirname(fpath)
-        self.run_dir = run_dir or glbl_cfg().get_derived_host_item(
-            self.suite, 'suite run directory')
-        self.log_dir = log_dir or glbl_cfg().get_derived_host_item(
-            self.suite, 'suite log directory')
-        self.work_dir = work_dir or glbl_cfg().get_derived_host_item(
-            self.suite, 'suite work directory')
-        self.share_dir = share_dir or glbl_cfg().get_derived_host_item(
-            self.suite, 'suite share directory')
+        self.run_dir = run_dir or get_suite_run_dir(self.suite)
+        self.log_dir = log_dir or get_suite_run_log_dir(self.suite)
+        self.share_dir = share_dir or get_suite_run_share_dir(self.suite)
+        self.work_dir = work_dir or get_suite_run_work_dir(self.suite)
         self.owner = owner
         self.run_mode = run_mode
         self.strict = strict
diff --git a/cylc/flow/daemonize.py b/cylc/flow/daemonize.py
index 31cef52ab5b..4f81fce4fe9 100644
--- a/cylc/flow/daemonize.py
+++ b/cylc/flow/daemonize.py
@@ -22,7 +22,7 @@
 import sys
 from time import sleep, time
 
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
+from cylc.flow.pathutil import get_suite_run_log_name
 
 
 SUITE_SCAN_INFO_TMPL = r"""
@@ -53,9 +53,9 @@ def daemonize(server):
     http://code.activestate.com/recipes/66012-fork-a-daemon-process-on-unix/
 
     """
-    logpath = glbl_cfg().get_derived_host_item(server.suite, 'suite log')
+    logfname = get_suite_run_log_name(server.suite)
     try:
-        old_log_mtime = os.stat(logpath).st_mtime
+        old_log_mtime = os.stat(logfname).st_mtime
     except OSError:
         old_log_mtime = None
     # fork 1
@@ -75,11 +75,11 @@ def daemonize(server):
                     #  LOG-PREFIX Suite server program: url=URL, pid=PID
                     # Otherwise, something has gone wrong, print the suite log
                     # and exit with an error.
-                    log_stat = os.stat(logpath)
+                    log_stat = os.stat(logfname)
                     if (log_stat.st_mtime == old_log_mtime or
                             log_stat.st_size == 0):
                         continue
-                    for line in open(logpath):
+                    for line in open(logfname):
                         if server.START_MESSAGE_PREFIX in line:
                             suite_url, suite_pid = (
                                 item.rsplit("=", 1)[-1]
@@ -88,7 +88,7 @@ def daemonize(server):
                         elif ' ERROR -' in line or ' CRITICAL -' in line:
                             # ERROR and CRITICAL before suite starts
                             try:
-                                sys.stderr.write(open(logpath).read())
+                                sys.stderr.write(open(logfname).read())
                                 sys.exit(1)
                             except IOError:
                                 sys.exit("Suite server program exited")
diff --git a/cylc/flow/etc/job.sh b/cylc/flow/etc/job.sh
index c7c7261e9dc..ae11ead17ec 100644
--- a/cylc/flow/etc/job.sh
+++ b/cylc/flow/etc/job.sh
@@ -121,8 +121,7 @@ cylc__job__main() {
     # System paths:
     # * suite directory (installed run-dir first).
     export PATH="${CYLC_SUITE_RUN_DIR}/bin:${CYLC_SUITE_DEF_PATH}/bin:${PATH}"
-    export
-    PYTHONPATH="${CYLC_SUITE_RUN_DIR}/lib/python:${CYLC_SUITE_DEF_PATH}/lib/python:${PYTHONPATH:-}"
+    export PYTHONPATH="${CYLC_SUITE_RUN_DIR}/lib/python:${CYLC_SUITE_DEF_PATH}/lib/python:${PYTHONPATH:-}"
     # Create share and work directories
     mkdir -p "${CYLC_SUITE_SHARE_DIR}" || true
     mkdir -p "$(dirname "${CYLC_TASK_WORK_DIR}")" || true
diff --git a/cylc/flow/exceptions.py b/cylc/flow/exceptions.py
index ec963ae7025..31bd6b49201 100644
--- a/cylc/flow/exceptions.py
+++ b/cylc/flow/exceptions.py
@@ -55,10 +55,6 @@ class SuiteConfigError(CylcConfigError):
     """Exception for configuration errors in a Cylc suite configuration."""
 
 
-class GlobalConfigError(CylcConfigError):
-    """Exception for configuration errors in a Cylc global configuration."""
-
-
 class GraphParseError(SuiteConfigError):
     """Exception for errors in Cylc suite graphing."""
 
diff --git a/cylc/flow/job_file.py b/cylc/flow/job_file.py
index 4037551a94c..540774e9a25 100644
--- a/cylc/flow/job_file.py
+++ b/cylc/flow/job_file.py
@@ -26,6 +26,9 @@
 from cylc.flow.batch_sys_manager import BatchSysManager
 from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 import cylc.flow.flags
+from cylc.flow.pathutil import (
+    get_remote_suite_run_dir,
+    get_remote_suite_work_dir)
 
 
 class JobFileWriter(object):
@@ -56,7 +59,8 @@ def write(self, local_job_file_path, job_conf, check_syntax=True):
         # variables: NEXT_CYCLE=$( cylc cycle-point --offset-hours=6 )
 
         tmp_name = local_job_file_path + '.tmp'
-        run_d = self._get_derived_host_item(job_conf, 'suite run directory')
+        run_d = get_remote_suite_run_dir(
+            job_conf['host'], job_conf['owner'], job_conf['suite_name'])
         try:
             with open(tmp_name, 'w') as handle:
                 self._write_header(handle, job_conf)
@@ -116,12 +120,6 @@ def _check_script_value(value):
                     return True
         return False
 
-    @staticmethod
-    def _get_derived_host_item(job_conf, key):
-        """Return derived host item from glbl_cfg()."""
-        return glbl_cfg().get_derived_host_item(
-            job_conf['suite_name'], key, job_conf["host"], job_conf["owner"])
-
     @staticmethod
     def _get_host_item(job_conf, key):
         """Return host item from glbl_cfg()."""
@@ -194,7 +192,8 @@ def _write_environment_1(self, handle, job_conf, run_d):
 
         handle.write('\n')
         # override and write task-host-specific suite variables
-        work_d = self._get_derived_host_item(job_conf, 'suite work root')
+        work_d = get_remote_suite_work_dir(
+            job_conf["host"], job_conf["owner"], job_conf['suite_name'])
         handle.write('\n    export CYLC_SUITE_RUN_DIR="%s"' % run_d)
         if work_d != run_d:
             # Note: not an environment variable, but used by job.sh
diff --git a/cylc/flow/loggingutil.py b/cylc/flow/loggingutil.py
index 08da1727390..7dfb7947b41 100644
--- a/cylc/flow/loggingutil.py
+++ b/cylc/flow/loggingutil.py
@@ -31,6 +31,7 @@
 
 
 from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
+from cylc.flow.pathutil import get_suite_run_log_name
 from cylc.flow.wallclock import (
     get_current_time_string, get_time_string_from_unix_time)
 
@@ -77,8 +78,7 @@ class TimestampRotatingFileHandler(logging.FileHandler):
     MIN_BYTES = 1024
 
     def __init__(self, suite, no_detach=False):
-        logging.FileHandler.__init__(
-            self, glbl_cfg().get_derived_host_item(suite, 'suite log'))
+        logging.FileHandler.__init__(self, get_suite_run_log_name(suite))
         self.no_detach = no_detach
         self.stamp = None
         self.formatter = CylcLogFormatter()
diff --git a/cylc/flow/pathutil.py b/cylc/flow/pathutil.py
new file mode 100644
index 00000000000..678b294995f
--- /dev/null
+++ b/cylc/flow/pathutil.py
@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+
+# THIS FILE IS PART OF THE CYLC SUITE ENGINE.
+# Copyright (C) 2008-2019 NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Functions to return paths to common suite files and directories."""
+
+import os
+from shutil import rmtree
+
+
+from cylc.flow import LOG
+from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
+
+
+def get_remote_suite_run_dir(host, owner, suite, *args):
+    """Return remote suite run directory, join any extra args."""
+    return os.path.join(
+        glbl_cfg().get_host_item('run directory', host, owner), suite, *args)
+
+
+def get_remote_suite_run_job_dir(host, owner, suite, *args):
+    """Return remote suite run directory, join any extra args."""
+    return get_remote_suite_run_dir(
+        host, owner, suite, 'log', 'job', *args)
+
+
+def get_remote_suite_work_dir(host, owner, suite, *args):
+    """Return remote suite work directory root, join any extra args."""
+    return os.path.join(
+        glbl_cfg().get_host_item('work directory', host, owner),
+        suite,
+        *args)
+
+
+def get_suite_run_dir(suite, *args):
+    """Return local suite run directory, join any extra args."""
+    return os.path.join(
+        glbl_cfg().get_host_item('run directory'), suite, *args)
+
+
+def get_suite_run_job_dir(suite, *args):
+    """Return suite run job (log) directory, join any extra args."""
+    return get_suite_run_dir(suite, 'log', 'job', *args)
+
+
+def get_suite_run_log_dir(suite, *args):
+    """Return suite run log directory, join any extra args."""
+    return get_suite_run_dir(suite, 'log', 'suite', *args)
+
+
+def get_suite_run_log_name(suite):
+    """Return suite run log file path."""
+    return get_suite_run_dir(suite, 'log', 'suite', 'log')
+
+
+def get_suite_run_rc_dir(suite, *args):
+    """Return suite run suite.rc log directory, join any extra args."""
+    return get_suite_run_dir(suite, 'log', 'suiterc', *args)
+
+
+def get_suite_run_pub_db_name(suite):
+    """Return suite run public database file path."""
+    return get_suite_run_dir(suite, 'log', 'db')
+
+
+def get_suite_run_share_dir(suite, *args):
+    """Return local suite work/share directory, join any extra args."""
+    return os.path.join(
+        glbl_cfg().get_host_item('work directory'), suite, 'share', *args)
+
+
+def get_suite_run_work_dir(suite, *args):
+    """Return local suite work/work directory, join any extra args."""
+    return os.path.join(
+        glbl_cfg().get_host_item('work directory'), suite, 'work', *args)
+
+
+def make_suite_run_tree(suite):
+    """Create all top-level cylc-run output dirs on the suite host."""
+    cfg = glbl_cfg().get()
+    # Roll archive
+    archlen = cfg['run directory rolling archive length']
+    dir_ = get_suite_run_dir(suite)
+    for i in range(archlen, -1, -1):  # archlen...0
+        if i > 0:
+            dpath = dir_ + '.' + str(i)
+        else:
+            dpath = dir_
+        if os.path.exists(dpath):
+            if i >= archlen:
+                # remove oldest backup
+                rmtree(dpath)
+            else:
+                # roll others over
+                os.rename(dpath, dir_ + '.' + str(i + 1))
+    # Create
+    for dir_ in (
+        get_suite_run_dir(suite),
+        get_suite_run_log_dir(suite),
+        get_suite_run_job_dir(suite),
+        get_suite_run_rc_dir(suite),
+        get_suite_run_share_dir(suite),
+        get_suite_run_work_dir(suite),
+    ):
+        if dir_:
+            os.makedirs(dir_, exist_ok=True)
+            LOG.debug('%s: directory created', dir_)
diff --git a/cylc/flow/scheduler.py b/cylc/flow/scheduler.py
index fdc4489018d..088b09838e7 100644
--- a/cylc/flow/scheduler.py
+++ b/cylc/flow/scheduler.py
@@ -48,6 +48,14 @@
     ReferenceLogFileHandler
 from cylc.flow.log_diagnosis import LogSpec
 from cylc.flow.network.server import SuiteRuntimeServer
+from cylc.flow.pathutil import (
+    get_suite_run_dir,
+    get_suite_run_log_dir,
+    get_suite_run_rc_dir,
+    get_suite_run_share_dir,
+    get_suite_run_work_dir,
+    make_suite_run_tree,
+)
 from cylc.flow.profiler import Profiler
 from cylc.flow.state_summary_mgr import StateSummaryMgr
 from cylc.flow.subprocpool import SubProcPool
@@ -145,14 +153,10 @@ def __init__(self, is_restart, options, args):
         # For user-defined batch system handlers
         sys.path.append(os.path.join(self.suite_dir, 'python'))
         sys.path.append(os.path.join(self.suite_dir, 'lib', 'python'))
-        self.suite_run_dir = glbl_cfg().get_derived_host_item(
-            self.suite, 'suite run directory')
-        self.suite_work_dir = glbl_cfg().get_derived_host_item(
-            self.suite, 'suite work directory')
-        self.suite_share_dir = glbl_cfg().get_derived_host_item(
-            self.suite, 'suite share directory')
-        self.suite_log_dir = glbl_cfg().get_derived_host_item(
-            self.suite, 'suite log directory')
+        self.suite_run_dir = get_suite_run_dir(self.suite)
+        self.suite_work_dir = get_suite_run_work_dir(self.suite)
+        self.suite_share_dir = get_suite_run_share_dir(self.suite)
+        self.suite_log_dir = get_suite_run_log_dir(self.suite)
 
         self.config = None
 
@@ -240,7 +244,7 @@ def start(self):
         """Start the server."""
         self._start_print_blurb()
 
-        glbl_cfg().create_cylc_run_tree(self.suite)
+        make_suite_run_tree(self.suite)
 
         if self.is_restart:
             self.suite_db_mgr.restart_upgrade()
@@ -983,8 +987,6 @@ def load_suiterc(self, is_reload=False):
         )
         self.suiterc_update_time = time()
         # Dump the loaded suiterc for future reference.
-        cfg_logdir = glbl_cfg().get_derived_host_item(
-            self.suite, 'suite config log directory')
         time_str = get_current_time_string(
             override_use_utc=True, use_basic_format=True,
             display_sub_seconds=False
@@ -995,8 +997,8 @@ def load_suiterc(self, is_reload=False):
             load_type = "restart"
         else:
             load_type = "run"
-        base_name = "%s-%s.rc" % (time_str, load_type)
-        file_name = os.path.join(cfg_logdir, base_name)
+        file_name = get_suite_run_rc_dir(
+            self.suite, f"{time_str}-{load_type}.rc")
         with open(file_name, "wb") as handle:
             handle.write(b"# cylc-version: %s\n" % CYLC_VERSION.encode())
             printcfg(self.config.cfg, none_str=None, handle=handle)
diff --git a/cylc/flow/scheduler_cli.py b/cylc/flow/scheduler_cli.py
index 2c60eeb093f..3bbe0b2f3af 100755
--- a/cylc/flow/scheduler_cli.py
+++ b/cylc/flow/scheduler_cli.py
@@ -20,11 +20,11 @@
 import os
 import sys
 
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 import cylc.flow.flags
 from cylc.flow.host_appointer import HostAppointer, EmptyHostList
 from cylc.flow.hostuserutil import is_remote_host
 from cylc.flow.option_parsers import CylcOptionParser as COP
+from cylc.flow.pathutil import get_suite_run_dir
 from cylc.flow.remote import remrun, remote_cylc_cmd
 from cylc.flow.scheduler import Scheduler
 from cylc.flow.suite_srv_files_mgr import (
@@ -123,9 +123,7 @@ def main(is_restart=False):
         SuiteSrvFilesManager().get_suite_source_dir(args[0], options.owner)
     except SuiteServiceFileError:
         # Source path is assumed to be the run directory
-        SuiteSrvFilesManager().register(
-            args[0],
-            glbl_cfg().get_derived_host_item(args[0], 'suite run directory'))
+        SuiteSrvFilesManager().register(args[0], get_suite_run_dir(args[0]))
 
     try:
         scheduler = Scheduler(is_restart, options, args)
diff --git a/cylc/flow/suite_srv_files_mgr.py b/cylc/flow/suite_srv_files_mgr.py
index 3b7ff3c029d..3b5e09f2e8f 100644
--- a/cylc/flow/suite_srv_files_mgr.py
+++ b/cylc/flow/suite_srv_files_mgr.py
@@ -26,6 +26,7 @@
 from cylc.flow import LOG
 from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.exceptions import SuiteServiceFileError
+from cylc.flow.pathutil import get_remote_suite_run_dir, get_suite_run_dir
 from cylc.flow.pkg_resources import extract_pkg_resources
 import cylc.flow.flags
 from cylc.flow.hostuserutil import (
@@ -345,8 +346,7 @@ def get_suite_srv_dir(self, reg, suite_owner=None):
         run_d = os.getenv("CYLC_SUITE_RUN_DIR")
         if (not run_d or os.getenv("CYLC_SUITE_NAME") != reg or
                 os.getenv("CYLC_SUITE_OWNER") != suite_owner):
-            run_d = glbl_cfg().get_derived_host_item(
-                reg, 'suite run directory')
+            run_d = get_suite_run_dir(reg)
         return os.path.join(run_d, self.DIR_BASE_SRV)
 
     def list_suites(self, regfilter=None):
@@ -615,9 +615,7 @@ def _load_remote_item(self, item, reg, owner, host):
         if item == self.FILE_BASE_CONTACT and not is_remote_host(host):
             # Attempt to read suite contact file via the local filesystem.
             path = r'%(run_d)s/%(srv_base)s' % {
-                'run_d': glbl_cfg().get_derived_host_item(
-                    reg, 'suite run directory', 'localhost', owner,
-                    replace_home=False),
+                'run_d': get_remote_suite_run_dir('localhost', owner, reg),
                 'srv_base': self.DIR_BASE_SRV,
             }
             content = self._load_local_item(item, path)
@@ -632,8 +630,7 @@ def _load_remote_item(self, item, reg, owner, host):
             r'''cat "%(run_d)s/%(srv_base)s/%(item)s"'''
         ) % {
             'prefix': prefix,
-            'run_d': glbl_cfg().get_derived_host_item(
-                reg, 'suite run directory', host, owner),
+            'run_d': get_remote_suite_run_dir(host, owner, reg),
             'srv_base': self.DIR_BASE_SRV,
             'item': item
         }
diff --git a/cylc/flow/task_events_mgr.py b/cylc/flow/task_events_mgr.py
index ffb3bcac551..c159a0c9e3f 100644
--- a/cylc/flow/task_events_mgr.py
+++ b/cylc/flow/task_events_mgr.py
@@ -39,6 +39,9 @@
 from cylc.flow import LOG
 from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.hostuserutil import get_host, get_user
+from cylc.flow.pathutil import (
+    get_remote_suite_run_job_dir,
+    get_suite_run_job_dir)
 from cylc.flow.subprocctx import SubProcContext
 from cylc.flow.task_action_timer import TaskActionTimer
 from cylc.flow.task_job_logs import (
@@ -577,11 +580,11 @@ def _process_job_logs_retrieval(self, schd_ctx, ctx, id_keys):
         cmd += ["--include=%s" % (include) for include in sorted(includes)]
         cmd.append("--exclude=/**")  # exclude everything else
         # Remote source
-        cmd.append(ctx.user_at_host + ":" + glbl_cfg().get_derived_host_item(
-            schd_ctx.suite, "suite job log directory", s_host, s_user) + "/")
+        cmd.append("%s:%s/" % (
+            ctx.user_at_host,
+            get_remote_suite_run_job_dir(s_host, s_user, schd_ctx.suite)))
         # Local target
-        cmd.append(glbl_cfg().get_derived_host_item(
-            schd_ctx.suite, "suite job log directory") + "/")
+        cmd.append(get_suite_run_job_dir(schd_ctx.suite) + "/")
         self.proc_pool.put_command(
             SubProcContext(ctx, cmd, env=dict(os.environ), id_keys=id_keys),
             self._job_logs_retrieval_callback, [schd_ctx])
diff --git a/cylc/flow/task_job_logs.py b/cylc/flow/task_job_logs.py
index 7a034f8f9f7..5b4760ae2ac 100644
--- a/cylc/flow/task_job_logs.py
+++ b/cylc/flow/task_job_logs.py
@@ -18,7 +18,7 @@
 """Define task job log filenames and option names."""
 
 import os
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
+from cylc.flow.pathutil import get_suite_run_job_dir
 
 # Task job log filenames.
 JOB_LOG_JOB = "job"
@@ -56,7 +56,7 @@ def get_task_job_id(point, name, submit_num=None):
 def get_task_job_log(suite, point, name, submit_num=None, suffix=None):
     """Return the full job log path."""
     args = [
-        glbl_cfg().get_derived_host_item(suite, "suite job log directory"),
+        get_suite_run_job_dir(suite),
         get_task_job_id(point, name, submit_num)]
     if suffix is not None:
         args.append(suffix)
diff --git a/cylc/flow/task_job_mgr.py b/cylc/flow/task_job_mgr.py
index fd4f7912c49..640dc996e64 100644
--- a/cylc/flow/task_job_mgr.py
+++ b/cylc/flow/task_job_mgr.py
@@ -37,17 +37,17 @@
 
 from cylc.flow import LOG
 from cylc.flow.batch_sys_manager import JobPollContext
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.hostuserutil import get_host, is_remote_host, is_remote_user
 from cylc.flow.job_file import JobFileWriter
-from cylc.flow.task_job_logs import (
-    JOB_LOG_JOB, get_task_job_log, get_task_job_job_log,
-    get_task_job_activity_log, get_task_job_id, NN)
+from cylc.flow.pathutil import get_remote_suite_run_job_dir
 from cylc.flow.subprocpool import SubProcPool
 from cylc.flow.subprocctx import SubProcContext
 from cylc.flow.task_action_timer import TaskActionTimer
 from cylc.flow.task_events_mgr import TaskEventsManager, log_task_job_activity
 from cylc.flow.task_message import FAIL_MESSAGE_PREFIX
+from cylc.flow.task_job_logs import (
+    JOB_LOG_JOB, get_task_job_log, get_task_job_job_log,
+    get_task_job_activity_log, get_task_job_id, NN)
 from cylc.flow.task_outputs import (
     TASK_OUTPUT_SUBMITTED, TASK_OUTPUT_STARTED, TASK_OUTPUT_SUCCEEDED,
     TASK_OUTPUT_FAILED)
@@ -282,8 +282,7 @@ def submit_task_jobs(self, suite, itasks, is_simulation=False):
             if remote_mode:
                 cmd.append('--remote-mode')
             cmd.append('--')
-            cmd.append(glbl_cfg().get_derived_host_item(
-                suite, 'suite job log directory', host, owner))
+            cmd.append(get_remote_suite_run_job_dir(host, owner, suite))
             # Chop itasks into a series of shorter lists if it's very big
             # to prevent overloading of stdout and stderr pipes.
             itasks = sorted(itasks, key=lambda itask: itask.identity)
@@ -651,8 +650,7 @@ def _run_job_cmd(self, cmd_key, suite, itasks, callback):
             if is_remote_user(owner):
                 cmd.append("--user=%s" % (owner))
             cmd.append("--")
-            cmd.append(glbl_cfg().get_derived_host_item(
-                suite, "suite job log directory", host, owner))
+            cmd.append(get_remote_suite_run_job_dir(host, owner, suite))
             job_log_dirs = []
             for itask in sorted(itasks, key=lambda itask: itask.identity):
                 job_log_dirs.append(get_task_job_id(
@@ -852,11 +850,8 @@ def _prep_submit_task_job_impl(self, suite, itask, rtconfig):
         self._create_job_log_path(suite, itask)
         job_d = get_task_job_id(
             itask.point, itask.tdef.name, itask.submit_num)
-        job_file_path = os.path.join(
-            glbl_cfg().get_derived_host_item(
-                suite, "suite job log directory",
-                itask.task_host, itask.task_owner),
-            job_d, JOB_LOG_JOB)
+        job_file_path = get_remote_suite_run_job_dir(
+            itask.task_host, itask.task_owner, suite, job_d, JOB_LOG_JOB)
         return {
             'batch_system_name': rtconfig['job']['batch system'],
             'batch_submit_command_template': (
diff --git a/cylc/flow/task_message.py b/cylc/flow/task_message.py
index f55ebd81ec4..bc79694a001 100644
--- a/cylc/flow/task_message.py
+++ b/cylc/flow/task_message.py
@@ -28,9 +28,9 @@
 import sys
 
 
-from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 import cylc.flow.flags
 from cylc.flow.network.client import SuiteRuntimeClient
+from cylc.flow.pathutil import get_suite_run_job_dir
 from cylc.flow.task_outputs import TASK_OUTPUT_STARTED, TASK_OUTPUT_SUCCEEDED
 from cylc.flow.wallclock import get_current_time_string
 
@@ -93,9 +93,7 @@ def _append_job_status_file(suite, task_job, event_time, messages):
     """Write messages to job status file."""
     job_log_name = os.getenv('CYLC_TASK_LOG_ROOT')
     if not job_log_name:
-        job_log_name = os.path.join(
-            glbl_cfg().get_derived_host_item(suite, 'suite job log directory'),
-            'job')
+        job_log_name = get_suite_run_job_dir(suite, task_job, 'job')
     try:
         job_status_file = open(job_log_name + '.status', 'a')
     except IOError:
diff --git a/cylc/flow/task_remote_mgr.py b/cylc/flow/task_remote_mgr.py
index cd1cbe634ea..12e00354115 100644
--- a/cylc/flow/task_remote_mgr.py
+++ b/cylc/flow/task_remote_mgr.py
@@ -36,6 +36,7 @@
 from cylc.flow.exceptions import TaskRemoteMgmtError
 import cylc.flow.flags
 from cylc.flow.hostuserutil import is_remote, is_remote_host, is_remote_user
+from cylc.flow.pathutil import get_remote_suite_run_dir
 from cylc.flow.subprocctx import SubProcContext
 from cylc.flow.task_remote_cmd import (
     FILE_BASE_UUID, REMOTE_INIT_DONE, REMOTE_INIT_NOT_REQUIRED)
@@ -95,14 +96,11 @@ def remote_host_select(self, host_str):
                     host_str = value  # command succeeded
             else:
                 # Command not launched (or already reset)
-                timeout = glbl_cfg().get(['task host select command timeout'])
-                if timeout:
-                    cmd = ['timeout', str(int(timeout)), 'bash', '-c', cmd_str]
-                else:
-                    cmd = ['bash', '-c', cmd_str]
                 self.proc_pool.put_command(
                     SubProcContext(
-                        'remote-host-select', cmd, env=dict(os.environ)),
+                        'remote-host-select',
+                        ['bash', '-c', cmd_str],
+                        env=dict(os.environ)),
                     self._remote_host_select_callback, [cmd_str])
                 self.remote_host_str_map[cmd_str] = None
                 return self.remote_host_str_map[cmd_str]
@@ -198,8 +196,7 @@ def remote_init(self, host, owner):
         if comm_meth in ['ssh']:
             cmd.append('--indirect-comm=%s' % comm_meth)
         cmd.append(str(self.uuid_str))
-        cmd.append(glbl_cfg().get_derived_host_item(
-            self.suite, 'suite run directory', host, owner))
+        cmd.append(get_remote_suite_run_dir(host, owner, self.suite))
         self.proc_pool.put_command(
             SubProcContext('remote-init', cmd, stdin_files=[tmphandle]),
             self._remote_init_callback,
@@ -237,8 +234,7 @@ def remote_tidy(self):
                 cmd.append('--user=%s' % owner)
             if cylc.flow.flags.debug:
                 cmd.append('--debug')
-            cmd.append(os.path.join(glbl_cfg().get_derived_host_item(
-                self.suite, 'suite run directory', host, owner)))
+            cmd.append(get_remote_suite_run_dir(host, owner, self.suite))
             procs[(host, owner)] = (
                 cmd,
                 Popen(cmd, stdout=PIPE, stderr=PIPE, stdin=open(os.devnull)))
diff --git a/cylc/flow/tests/test_loggingutil.py b/cylc/flow/tests/test_loggingutil.py
index 2f611db07cb..4a297f24bb5 100644
--- a/cylc/flow/tests/test_loggingutil.py
+++ b/cylc/flow/tests/test_loggingutil.py
@@ -28,8 +28,13 @@
 
 class TestLoggingutil(unittest.TestCase):
 
+    @mock.patch("cylc.flow.loggingutil.get_suite_run_log_name")
     @mock.patch("cylc.flow.loggingutil.glbl_cfg")
-    def test_value_error_raises_system_exit(self, mocked_glbl_cfg):
+    def test_value_error_raises_system_exit(
+        self,
+        mocked_glbl_cfg,
+        mocked_get_suite_run_log_name,
+    ):
         """Test that a ValueError when writing to a log stream won't result
         in multiple exceptions (what could lead to infinite loop in some
         occasions. Instead, it **must** raise a SystemExit"""
@@ -37,8 +42,8 @@ def test_value_error_raises_system_exit(self, mocked_glbl_cfg):
             # mock objects used when creating the file handler
             mocked = mock.MagicMock()
             mocked_glbl_cfg.return_value = mocked
-            mocked.get_derived_host_item.return_value = tf.name
             mocked.get.return_value = 100
+            mocked_get_suite_run_log_name.return_value = tf.name
             file_handler = TimestampRotatingFileHandler("suiteA", False)
             # next line is important as pytest can have a "Bad file descriptor"
             # due to a FileHandler with default "a" (pytest tries to r/w).
diff --git a/cylc/flow/tests/test_pathutil.py b/cylc/flow/tests/test_pathutil.py
new file mode 100644
index 00000000000..6a5f1c53457
--- /dev/null
+++ b/cylc/flow/tests/test_pathutil.py
@@ -0,0 +1,147 @@
+#!/usr/bin/env python3
+
+# THIS FILE IS PART OF THE CYLC SUITE ENGINE.
+# Copyright (C) 2008-2019 NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Tests for "cylc.flow.pathutil"."""
+
+from unittest import TestCase
+from unittest.mock import call, patch, MagicMock
+
+from cylc.flow.pathutil import (
+    get_remote_suite_run_dir,
+    get_remote_suite_run_job_dir,
+    get_remote_suite_work_dir,
+    get_suite_run_dir,
+    get_suite_run_job_dir,
+    get_suite_run_log_dir,
+    get_suite_run_log_name,
+    get_suite_run_pub_db_name,
+    get_suite_run_rc_dir,
+    get_suite_run_share_dir,
+    get_suite_run_work_dir,
+    make_suite_run_tree,
+)
+
+
+class TestPathutil(TestCase):
+    """Tests for functions in "cylc.flow.pathutil"."""
+
+    @patch('cylc.flow.pathutil.glbl_cfg')
+    def test_get_remote_suite_run_dirs(self, mocked_glbl_cfg):
+        """Usage of get_remote_suite_run_*dir."""
+        mocked = MagicMock()
+        mocked_glbl_cfg.return_value = mocked
+        mocked.get_host_item.return_value = '/home/sweet/cylc-run'
+        # func = get_remote_* function to test
+        # cfg = configuration used in mocked global configuration
+        # tail1 = expected tail of return value from configuration
+        # args = extra *args
+        # tail2 = expected tail of return value from extra args
+        for func, cfg, tail1 in (
+            (get_remote_suite_run_dir, 'run directory', ''),
+            (get_remote_suite_run_job_dir, 'run directory', '/log/job'),
+            (get_remote_suite_work_dir, 'work directory', ''),
+        ):
+            for args, tail2 in (
+                ((), ''),
+                (('comes', 'true'), '/comes/true'),
+            ):
+                self.assertEqual(
+                    f'/home/sweet/cylc-run/my-suite/dream{tail1}{tail2}',
+                    func('myhost', 'myuser', 'my-suite/dream', *args),
+                )
+                mocked.get_host_item.assert_called_with(
+                    cfg, 'myhost', 'myuser')
+                mocked.get_host_item.reset_mock()
+
+    @patch('cylc.flow.pathutil.glbl_cfg')
+    def test_get_suite_run_dirs(self, mocked_glbl_cfg):
+        """Usage of get_suite_run_*dir."""
+        mocked = MagicMock()
+        mocked_glbl_cfg.return_value = mocked
+        mocked.get_host_item.return_value = '/home/sweet/cylc-run'
+        # func = get_remote_* function to test
+        # cfg = configuration used in mocked global configuration
+        # tail1 = expected tail of return value from configuration
+        # args = extra *args
+        # tail2 = expected tail of return value from extra args
+        for func, cfg, tail1 in (
+            (get_suite_run_dir, 'run directory', ''),
+            (get_suite_run_job_dir, 'run directory', '/log/job'),
+            (get_suite_run_log_dir, 'run directory', '/log/suite'),
+            (get_suite_run_rc_dir, 'run directory', '/log/suiterc'),
+            (get_suite_run_share_dir, 'work directory', '/share'),
+            (get_suite_run_work_dir, 'work directory', '/work'),
+        ):
+            for args, tail2 in (
+                ((), ''),
+                (('comes', 'true'), '/comes/true'),
+            ):
+                self.assertEqual(
+                    f'/home/sweet/cylc-run/my-suite/dream{tail1}{tail2}',
+                    func('my-suite/dream', *args),
+                )
+                mocked.get_host_item.assert_called_with(cfg)
+                mocked.get_host_item.reset_mock()
+
+    @patch('cylc.flow.pathutil.glbl_cfg')
+    def test_get_suite_run_names(self, mocked_glbl_cfg):
+        """Usage of get_suite_run_*name."""
+        mocked = MagicMock()
+        mocked_glbl_cfg.return_value = mocked
+        mocked.get_host_item.return_value = '/home/sweet/cylc-run'
+        # func = get_remote_* function to test
+        # cfg = configuration used in mocked global configuration
+        # tail1 = expected tail of return value from configuration
+        for func, cfg, tail1 in (
+            (get_suite_run_log_name, 'run directory', '/log/suite/log'),
+            (get_suite_run_pub_db_name, 'run directory', '/log/db'),
+        ):
+            self.assertEqual(
+                f'/home/sweet/cylc-run/my-suite/dream{tail1}',
+                func('my-suite/dream'),
+            )
+            mocked.get_host_item.assert_called_with(cfg)
+            mocked.get_host_item.reset_mock()
+
+    @patch('cylc.flow.pathutil.os.makedirs')
+    @patch('cylc.flow.pathutil.glbl_cfg')
+    def test_make_suite_run_tree(self, mocked_glbl_cfg, mocked_makedirs):
+        """Usage of make_suite_run_tree."""
+        mocked = MagicMock()
+        mocked_glbl_cfg.return_value = mocked
+        mocked.get_host_item.return_value = '/home/sweet/cylc-run'
+        mocked_cfg = MagicMock()
+        mocked_cfg['run directory rolling archive length'] = 0
+        mocked.get.return_value = mocked_cfg
+        make_suite_run_tree('my-suite/dream')
+        self.assertEqual(mocked_makedirs.call_count, 6)
+        mocked_makedirs.assert_has_calls((
+            call(f'/home/sweet/cylc-run/my-suite/dream{tail}', exist_ok=True)
+            for tail in (
+                '',
+                '/log/suite',
+                '/log/job',
+                '/log/suiterc',
+                '/share',
+                '/work',
+            )
+        ))
+
+
+if __name__ == '__main__':
+    from unittest import main
+    main()
diff --git a/tests/host-select/01-timeout.t b/tests/host-select/01-timeout.t
deleted file mode 100644
index 0245384103c..00000000000
--- a/tests/host-select/01-timeout.t
+++ /dev/null
@@ -1,32 +0,0 @@
-#!/bin/bash
-# THIS FILE IS PART OF THE CYLC SUITE ENGINE.
-# Copyright (C) 2008-2019 NIWA & British Crown (Met Office) & Contributors.
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-#-------------------------------------------------------------------------------
-# Test host selection, with a command that times out.
-. "$(dirname "$0")/test_header"
-
-set_test_number 3
-
-install_suite "${TEST_NAME_BASE}" "${TEST_NAME_BASE}"
-
-create_test_globalrc 'task host select command timeout = PT1S'
-run_ok "${TEST_NAME_BASE}-validate" cylc validate "${SUITE_NAME}"
-suite_run_ok "${TEST_NAME_BASE}" \
-    cylc run --reference-test --debug --no-detach "${SUITE_NAME}"
-grep_ok 'ERROR - \[jobs-submit cmd\] (remote host select)' \
-    "$(cylc get-global-config --print-run-dir)/${SUITE_NAME}/log/suite/log"
-purge_suite "${SUITE_NAME}"
-exit
diff --git a/tests/job-submission/06-garbage.t b/tests/job-submission/06-garbage.t
index 654e6189541..4fc6349f3ee 100755
--- a/tests/job-submission/06-garbage.t
+++ b/tests/job-submission/06-garbage.t
@@ -20,7 +20,7 @@
 
 set_test_number 2
 install_suite "${TEST_NAME_BASE}" "${TEST_NAME_BASE}"
-if [[ -n "${PYTHONPATH}" ]]; then
+if [[ -n "${PYTHONPATH:-}" ]]; then
     export PYTHONPATH="${PWD}/lib:${PYTHONPATH}"
 else
     export PYTHONPATH="${PWD}/lib"
diff --git a/tests/rnd/02-lib-python-in-job/suite.rc b/tests/rnd/02-lib-python-in-job/suite.rc
index 9284fe88d54..2ed2a06dc11 100644
--- a/tests/rnd/02-lib-python-in-job/suite.rc
+++ b/tests/rnd/02-lib-python-in-job/suite.rc
@@ -12,7 +12,7 @@
             grep -q "${CYLC_SUITE_RUN_DIR}/lib/python" <<< "${PYTHONPATH}"
 
             # run a toy example
-            python -c '
+            python3 -c '
             from pub import beer
             assert beer.drink() == "98 bottles of beer on the wall."
             assert beer.drink() == "97 bottles of beer on the wall."