Scripts can use Python or bundled Lua 5.4.9. Choose a .py or .lua file in Script → Run; logon scripts, saved script commands and –script also accept both. Use Script → Cancel to stop the current tab’s worker. Script errors appear in the Activity pane. The Lua scripting guide includes its syntax and API reference.

Lua API guide and examples

Choose Script → Run and select a .py file. Python runs separately from the desktop UI. The application passes a private, per-instance local connection token and the originating tab ID; changing focus does not retarget the script. Cancellation terminates the script process and leaves the connection open.

Linux uses configured/system Python 3. Windows packages include a private Python runtime. Select a different interpreter under Global Settings → Automation if needed. The lantern module uses only the standard library.

from lantern import app
 
tab = app.GetScriptTab()
tab.Screen.Send("printf '%s%s\\n' 'terminal-' 'ready'\r")
if not tab.Screen.WaitForString("terminal-ready", 5):
    raise TimeoutError("Endpoint did not respond")
print(tab.Caption, tab.Screen.Rows, tab.Screen.Columns)

Build test prompts from pieces so a wait does not match its own echoed command line. A screen send records the incoming-stream position before transmission, so an immediate reply is retained for the following wait.

• app.Version, app.Arguments.Count/GetArg(0), app.GetScriptTab(), app.GetActiveTab(), app.GetTabCount(), app.GetTab(1), app.Sleep(milliseconds) and app.Quit().
• Tabs: Caption, one-based Index, Screen, Session, Activate(), Clone(), Close(), ConnectSftp(), ResetCaption().
• Screen: Rows, Columns, one-based CurrentRow/CurrentColumn, Selection, Send(text), binary SendBytes(data), Get/Get2(top,left,bottom,right), Clear(), SendKeys(), SendSpecial(), WaitForCursor(), WaitForString(), WaitForStrings() and ReadString().
• Matching: IgnoreCase, capture IgnoreEscape, Synchronous and MatchIndex. Wait timeouts default to seconds; zero waits until match/disconnect/cancellation. WaitForStrings returns one-based index or zero on timeout; WaitForString returns a boolean. ReadString excludes the matched delimiter and returns empty text on timeout.
• Session: Connected, Logging, LogFileName, Config, Disconnect(), Connect(profile), ConnectInTab(profile), and Log(enabled, append, raw).
• Configuration: GetOption(key), SetOption(key,value) and Save(). Keys are the typed application keys in src/config.cpp, such as fontSize, logPath, host, port and keyFile.
• Clipboard: app.Clipboard.Text.
• Dialogs: app.Dialog.MessageBox(text,title), Prompt(text,title,default,password) and FileOpenDialog(title).

Get2 retains line separators; Get concatenates lines. Closed/locked sessions and invalid coordinates produce explicit errors. A session disconnected while waiting raises LanternError. Capture is bounded; truncation raises an error rather than silently dropping the beginning of a response.

The comprehensive SCRIPTING-API.md defines the larger API contract. Members outside the included interface above are not supplied by this release. Lua uses the same authenticated application API through its bundled worker; see LUA-SCRIPTING.md for language-specific details.

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