feat: add fcron command fallback

src/cronboard_widgets/CronCommand.py

@@ -0,0 +1,46 @@
+import shlex
+from shutil import which
+
+import crontab as crontab_module
+from crontab import CronTab
+
+
+def get_local_crontab_command() -> str:
+    """Return the installed crontab-compatible command."""
+    for command in ("crontab", "fcrontab"):
+        command_path = which(command)
+        if command_path:
+            return command_path
+    return crontab_module.CRON_COMMAND
+
+
+def create_user_crontab() -> CronTab:
+    """Create a user CronTab using crontab or fcrontab when available."""
+    original_command = crontab_module.CRON_COMMAND
+    crontab_module.CRON_COMMAND = get_local_crontab_command()
+    try:
+        return CronTab(user=True)
+    finally:
+        crontab_module.CRON_COMMAND = original_command
+
+
+def remote_crontab_command(*args: str) -> str:
+    quoted_args = " ".join(shlex.quote(str(arg)) for arg in args if arg)
+    suffix = f" {quoted_args}" if quoted_args else ""
+    return (
+        "if command -v crontab >/dev/null 2>&1; "
+        f"then crontab{suffix}; "
+        f"else fcrontab{suffix}; fi"
+    )
+
+
+def remote_crontab_list_command(crontab_user: str | None = None) -> str:
+    if crontab_user:
+        return remote_crontab_command("-u", crontab_user, "-l")
+    return remote_crontab_command("-l")
+
+
+def remote_crontab_write_command(crontab_user: str | None = None) -> str:
+    if crontab_user:
+        return remote_crontab_command("-u", crontab_user, "-")
+    return remote_crontab_command("-")

src/cronboard_widgets/CronCreator.py

@@ -15,6 +15,7 @@
     PathDropdownItem,
 )
 from cron_descriptor import Options, ExpressionDescriptor
+from cronboard_widgets.CronCommand import remote_crontab_write_command
 
 
 CRON_ALIASES = {
@@ -350,11 +351,7 @@ def write_cron_changes(self):
         if self.remote and self.ssh_client:
             try:
                 new_crontab_content = self.cron.render()
-                crontab_cmd = (
-                    f"crontab -u {self.crontab_user} -"
-                    if self.crontab_user
-                    else "crontab -"
-                )
+                crontab_cmd = remote_crontab_write_command(self.crontab_user)
                 stdin, _, stderr = self.ssh_client.exec_command(crontab_cmd)
                 stdin.write(new_crontab_content)
                 stdin.channel.shutdown_write()

src/cronboard_widgets/CronDeleteConfirmation.py

@@ -1,9 +1,12 @@
 from textual.app import ComposeResult
-from crontab import CronTab
 from textual.binding import Binding
 from textual.widgets import Button, Label
 from textual.containers import Grid, Horizontal, Vertical
 from textual.screen import ModalScreen
+from cronboard_widgets.CronCommand import (
+    create_user_crontab,
+    remote_crontab_write_command,
+)
 
 
 class CronDeleteConfirmation(ModalScreen[bool]):
@@ -22,7 +25,7 @@ def __init__(
         super().__init__()
         self.server = server
         self.job = job
-        self.cron = cron if cron else CronTab(user=True)
+        self.cron = cron if cron else create_user_crontab()
         self.remote = remote
         self.ssh_client = ssh_client
         self.message = message
@@ -79,11 +82,7 @@ def write_remote_crontab(self):
         try:
             new_crontab_content = self.cron.render()
 
-            crontab_cmd = (
-                f"crontab -u {self.crontab_user} -"
-                if self.crontab_user
-                else "crontab -"
-            )
+            crontab_cmd = remote_crontab_write_command(self.crontab_user)
             stdin, _, stderr = self.ssh_client.exec_command(crontab_cmd)
             stdin.write(new_crontab_content)
             stdin.channel.shutdown_write()

src/cronboard_widgets/CronTable.py

@@ -5,6 +5,11 @@
 from datetime import datetime
 from rich.text import Text
 from cronboard_widgets.CronInputSearch import CronInputSearch
+from cronboard_widgets.CronCommand import (
+    create_user_crontab,
+    remote_crontab_list_command,
+    remote_crontab_write_command,
+)
 
 
 class CronTable(DataTable):
@@ -35,17 +40,13 @@ def __init__(self, remote=False, ssh_client=None, crontab_user=None, **kwargs):
         self._search_query: str = ""
 
     def on_mount(self) -> None:
-        self.cron: CronTab = CronTab(user=True)
+        self.cron: CronTab = create_user_crontab()
         self.add_columns(
             "ID", "Expression", "Command", "Last Run", "Next Run", "Status"
         )
 
         if self.remote and self.ssh_client:
-            crontab_cmd = (
-                f"crontab -u {self.crontab_user} -l"
-                if self.crontab_user
-                else "crontab -l"
-            )
+            crontab_cmd = remote_crontab_list_command(self.crontab_user)
             _, stdout, _ = self.ssh_client.exec_command(crontab_cmd)
             exit_status = stdout.channel.recv_exit_status()
 
@@ -170,11 +171,7 @@ def action_delete_cronjob_keybind(self, job) -> None:
     def action_refresh(self) -> None:
         """Refresh the cronjob list."""
         if self.remote and self.ssh_client:
-            crontab_cmd = (
-                f"crontab -u {self.crontab_user} -l"
-                if self.crontab_user
-                else "crontab -l"
-            )
+            crontab_cmd = remote_crontab_list_command(self.crontab_user)
             _, stdout, _ = self.ssh_client.exec_command(crontab_cmd)
             exit_status = stdout.channel.recv_exit_status()
 
@@ -185,7 +182,7 @@ def action_refresh(self) -> None:
 
             self.ssh_cron = CronTab(tab=self.crontab_content)
         else:
-            self.cron = CronTab(user=True)
+            self.cron = create_user_crontab()
         self.load_crontabs()
         self.refresh_bindings()
 
@@ -350,11 +347,7 @@ def write_remote_crontab(self):
         try:
             new_crontab_content = self.ssh_cron.render()
 
-            crontab_cmd = (
-                f"crontab -u {self.crontab_user} -"
-                if self.crontab_user
-                else "crontab -"
-            )
+            crontab_cmd = remote_crontab_write_command(self.crontab_user)
             stdin, _, stderr = self.ssh_client.exec_command(crontab_cmd)
             stdin.write(new_crontab_content)
             stdin.channel.shutdown_write()

tests/CronCommand_test.py

@@ -0,0 +1,53 @@
+import crontab as crontab_module
+
+from cronboard_widgets import CronCommand
+
+
+def test_get_local_crontab_command_prefers_crontab(mocker):
+    mocker.patch(
+        "cronboard_widgets.CronCommand.which",
+        side_effect=lambda command: f"/usr/bin/{command}"
+        if command == "crontab"
+        else None,
+    )
+
+    assert CronCommand.get_local_crontab_command() == "/usr/bin/crontab"
+
+
+def test_get_local_crontab_command_uses_fcrontab_when_crontab_missing(mocker):
+    mocker.patch(
+        "cronboard_widgets.CronCommand.which",
+        side_effect=lambda command: f"/usr/bin/{command}"
+        if command == "fcrontab"
+        else None,
+    )
+
+    assert CronCommand.get_local_crontab_command() == "/usr/bin/fcrontab"
+
+
+def test_create_user_crontab_uses_detected_command_and_restores_default(mocker):
+    mocker.patch(
+        "cronboard_widgets.CronCommand.get_local_crontab_command",
+        return_value="/usr/bin/fcrontab",
+    )
+    cron_tab = mocker.patch("cronboard_widgets.CronCommand.CronTab")
+    original_command = crontab_module.CRON_COMMAND
+
+    CronCommand.create_user_crontab()
+
+    cron_tab.assert_called_once_with(user=True)
+    assert crontab_module.CRON_COMMAND == original_command
+
+
+def test_remote_crontab_list_command_uses_crontab_with_fcrontab_fallback():
+    assert CronCommand.remote_crontab_list_command() == (
+        "if command -v crontab >/dev/null 2>&1; "
+        "then crontab -l; else fcrontab -l; fi"
+    )
+
+
+def test_remote_crontab_write_command_quotes_user():
+    assert CronCommand.remote_crontab_write_command("cron user") == (
+        "if command -v crontab >/dev/null 2>&1; "
+        "then crontab -u 'cron user' -; else fcrontab -u 'cron user' -; fi"
+    )

tests/CronDeleteConfirmation_test.py

@@ -1,5 +1,6 @@
 import pytest
 from cronboard_widgets.CronDeleteConfirmation import CronDeleteConfirmation
+from cronboard_widgets.CronCommand import remote_crontab_write_command
 from .conftest import create_event, create_job_and_cron, make_remote_command
 from cronboard.app import CronBoard
 from pytest_mock import MockerFixture
@@ -75,7 +76,7 @@ def test_write_remote_crontab(mocker: MockerFixture):
     result = modal.write_remote_crontab()
 
     assert result is True
-    ssh_client.exec_command.assert_called_once_with("crontab -u root -")
+    ssh_client.exec_command.assert_called_once_with(remote_crontab_write_command("root"))
     stdin.write.assert_called_once_with("* * * * * echo hello")
     stdin.channel.shutdown_write.assert_called_once_with()
 
@@ -92,4 +93,4 @@ def test_write_remote_crontab_error(mocker: MockerFixture):
     result = modal.write_remote_crontab()
 
     assert result is False
-    ssh_client.exec_command.assert_called_once_with("crontab -")
+    ssh_client.exec_command.assert_called_once_with(remote_crontab_write_command())

tests/conftest.py

@@ -25,9 +25,7 @@ def app(mocker: MockerFixture):
     fake_cron = mocker.MagicMock()
     fake_cron.__iter__ = mocker.MagicMock(side_effect=lambda: iter([fake_job]))
     mocker.patch("cronboard_widgets.CronTable.CronTab", return_value=fake_cron)
-    mocker.patch(
-        "cronboard_widgets.CronDeleteConfirmation.CronTab", return_value=fake_cron
-    )
+    mocker.patch("cronboard_widgets.CronCommand.CronTab", return_value=fake_cron)
     yield CronBoard()