Configuring UDB¶

This section lists each of UDB’s configuration parameters, together with a description, or a link to a description.

Terminal Visual Studio Code

Parameters can be configured in three ways:

Using Configuration commands in Initialization files.
Passing command-line options to udb.
Setting environment variables with names starting UNDO_.

Autorun mode¶

After attaching to or launching a program, continue the program automatically.

By default, UDB stops the program after attaching or launching.

Set this using the --autorun command-line option, or set UNDO_autorun to true in the environment.

Batch mode¶

UDB does not take input from the user, and exits as soon as it has processed all the --command and --eval-command options. Implies Quiet startup.

Set this using the --batch command-line option. or set UNDO_batch to true in the environment.

Checking for updates¶

Whether UDB checks for a newer release at start-up.

auto (the default) checks if it is a day or more since the last check; yes always checks; no and never don’t check.

If auto or never, the setting becomes the new default.

Set this using the --checkupdates command-line option or the UNDO_checkupdates environment variable.

Deferring recording¶

See Starting UDB with recording disabled.

Go to end after loading¶

See Going to the end of execution history after loading.

Quiet startup¶

Don’t print version number and licensing information on startup.

Set this using the --quiet command-line option, or set UNDO_quiet to true in the environment.

Parameters can be configured in four ways:

Use Configuration commands in Initialization files.
Pass command-line options to udb.

To pass command-line arguments to udb, select Open Configurations from the Run menu, find the launch configuration you want to configure, and update the "miDebuggerArgs" field. For example, to set the maximum event log size to 2GB:
When using UDB 6.8 or later: update the "udbConfiguration" key in the launch configuration, workspace settings, or user settings.

This must be an object mapping configuration parameters to their values. Any documented environment variable starting UNDO_ can be configured here. For example, to set the event log size and the number of snapshots:
```
"udbConfiguration": {
    "UNDO_event_log_max": "2G",
    "UNDO_snapshots": 20
}
```
Write a wrapper script that updates the environment, exports the variables, and finally execs udb. Then edit the launch configuration and update the "miDebuggerPath" field so that it names the wrapper script.

For example, to set the event log size, using a POSIX-compatible shell:
```
#!/bin/sh

# Increase the size of UDB's event log to 2GB - see https://docs.undo.io/EventLog.html
export UNDO_event_log_max=2G

exec udb "$@"
```
For csh the equivalent exec command is exec udb $*:q.

Note

You can’t configure UDB via the "environment" field in the launch configuration, as that sets the environment of the program being debugged instead.

Bbcount regular expression¶

See Controlling how bbcounts are detected.

Log file pattern¶

See Go to time via link in a log file.

Stop at entry¶

See Going to the start of execution history after loading.

Asynchronous I/O mode¶

See Debugging programs using asynchronous I/O with UDB.

Event log mode¶

See Using a straight event log.

Instrumentation heap size¶

The size of the just-in-time translation cache, as a number followed by an optional multiplier (K for kilobytes, M for megabytes, or G for gigabytes), or 0 to choose a suitable size.

The Undo Engine uses just-in-time compilation in order to record the execution history of the program being debugged, and maintains a cache of translated code. The minimum size for the cache is 32M, which will allow approximately 3.2MB of x86 native code to be translated. Programs with a very large working set of instructions may benefit from a larger value.

Set this using the --instr-heapsize command-line option or the UNDO_instrheapsize environment variable.

ioctl descriptions¶

See Self-service configuration.

Maximum event log size¶

See Configuring event log size.

Memory pressure threshold¶

See Snapshots adaptation.

Replay standard streams¶

Replay writes to standard output and standard error.

Side effects are normally suppressed in replay, but for orientation when debugging it can be helpful to replay writes to the standard streams.

Turn this off by setting UNDO_replay_standard_streams=false in the environment.

Maximum number of snapshots¶

See Configuring snapshots.

Temporary directory root¶

Directory used by UDB for its temporary files.

By default, UDB uses one of the directories specified by the Temporary directory roots configuration parameter.

Set this using the --tmpdir-root command-line option, or the UNDO_tmpdir_root environment variable.

Temporary directory roots¶

Semicolon-separated list of directories where temporary files can be placed.

By default, temporary files are placed in /tmp or /var/tmp.

Set this using the UNDO_tmpdir_roots environment variable.

Timezone¶

See Timezones.