Welcome to the Undo documentation!


This documentation explains how to use UDB - a powerful Time Travel Debugger for Linux based applications, and LiveRecorder - Undo’s flagship product platform for rapid software defect diagnosis & resolution.

UDB allows you to go back to any point in the debuggee’s execution history, including stepping backwards and forwards by individual instructions, source lines, function calls and so on. It can regenerate the complete state of the debuggee process at any point in its execution, including information that is destroyed during execution.

LiveRecorder includes:

  • The UDB Time Travel Debugger.
  • The LiveRecorder library which can be integrated into any Linux application to give it recording capabilities.
  • The live-record command-line tool which allows users to record the execution of a process on the command line.

Version History

Release 6.3
  • Bookmarks that you place when replaying a LiveRecorder recording in UDB are automatically persisted across debugging sessions.
  • UDB displays a progress indicator when performing a long-running time travel operation.
  • Further improved the performance of the reverse-next command and other reverse operations, and improved the correctness of these operations when debugging highly optimized code.
  • UDB now uses styles and colours in the text printed at startup.
Release 6.2
  • Improved performance of reverse operations in a number of situations including long-running operations and operations which stay in the same thread.
  • Deprecated all command line options starting with --undodb- in favour of options without any prefix. Refer to the changelog.txt file or product documentation for details.
Release 6.1
  • UDB is the new name for UndoDB. Existing --undodb command-line options will be retained for 6.x releases.
  • Upgraded the version of GDB that is packaged with UDB from 8.1 to 9.2. New GDB features, such as new commands and styled output, are described at GDB News under the relevant sections.
  • Upgraded the version of Python that is packaged with UDB and that is used by C++ pretty-printers from 2.7 to 3.6. Python 2 only pretty printers shipped by older supported distros are converted automatically at load time into Python 3.
  • The Log Jump feature is now enabled for all existing and new UDB and LiveRecorder customers.
Release 6.0
  • Support for applications written in the Java language.
  • Recordings are portable across machines with different CPU microarchitectures. See Recording Portability for details.
  • Core engine 25%-100% faster than 5.0 on diverse workloads.
Release 5.3
  • Support for applications written in the Java language [Beta].
  • Log Jump supports jumping from a line in a log file to the location and time in the program where it was emitted.
  • Post Failure Logging tool to insert logging statements into a deployed application. Enables diagnosing applications deployed in PII and IP-sensitive environments.
  • UDB Automation API to automate workflows in UDB using Python.
Release 5.2
  • Support for applications written in the Java language [Alpha].
  • Support for AVX-512 x86 instructions (avx512f, avx512bw, avx512cd, avx512dq, avx512vl).
  • Increased default event log size to 256MB when recording 32-bit processes and 1GB when recording 64-bit processes.
Release 5.1
  • Support for applications written in the Go language, see GoLand and Go Delve.
  • Fast Switch between inferiors when replaying MPC recordings.
  • Time Limits allow all navigation within a recording to be constrained within a time (bbcount) range. See help uset time-limits in udb.
  • Support for x86 Memory Protection Keys (pkeys).
Release 5.0: