Debugging with GDB: Hurd Native

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#### 21.1.5 Commands Specific to GNU Hurd Systems

This subsection describes GDB commands specific to the GNU Hurd native debugging.

`set signals`
`set sigs`

  This command toggles the state of inferior signal interception by GDB. Mach exceptions, such as breakpoint traps, are not affected by this command. `sigs` is a shorthand alias for `signals`.

`show signals`
`show sigs`

  Show the current state of intercepting inferior’s signals.

`set signal-thread`
`set sigthread`

  This command tells GDB which thread is the `libc` signal thread. That thread is run when a signal is delivered to a running process. `set sigthread` is the shorthand alias of `set signal-thread`.

`show signal-thread`
`show sigthread`

  These two commands show which thread will run when the inferior is delivered a signal.

`set stopped`

  This commands tells GDB that the inferior process is stopped, as with the `SIGSTOP` signal. The stopped process can be continued by delivering a signal to it.

`show stopped`

  This command shows whether GDB thinks the debuggee is stopped.

`set exceptions`

  Use this command to turn off trapping of exceptions in the inferior. When exception trapping is off, neither breakpoints nor single-stepping will work. To restore the default, set exception trapping on.

`show exceptions`

  Show the current state of trapping exceptions in the inferior.

`set task pause`

  This command toggles task suspension when GDB has control. Setting it to on takes effect immediately, and the task is suspended whenever GDB gets control. Setting it to off will take effect the next time the inferior is continued. If this option is set to off, you can use `set thread default pause on` or `set thread pause on` (see below) to pause individual threads.

`show task pause`

  Show the current state of task suspension.

`set task detach-suspend-count`

  This command sets the suspend count the task will be left with when GDB detaches from it.

`show task detach-suspend-count`

  Show the suspend count the task will be left with when detaching.

`set task exception-port`
`set task excp`

  This command sets the task exception port to which GDB will forward exceptions. The argument should be the value of the send rights of the task. `set task excp` is a shorthand alias.

`set noninvasive`

  This command switches GDB to a mode that is the least invasive as far as interfering with the inferior is concerned. This is the same as using `set task pause`, `set exceptions`, and `set signals` to values opposite to the defaults.

`info send-rights`
`info receive-rights`
`info port-rights`
`info port-sets`
`info dead-names`
`info ports`
`info psets`

  These commands display information about, respectively, send rights, receive rights, port rights, port sets, and dead names of a task. There are also shorthand aliases: `info ports` for `info port-rights` and `info psets` for `info port-sets`.

`set thread pause`

  This command toggles current thread suspension when GDB has control. Setting it to on takes effect immediately, and the current thread is suspended whenever GDB gets control. Setting it to off will take effect the next time the inferior is continued. Normally, this command has no effect, since when GDB has control, the whole task is suspended. However, if you used `set task pause off` (see above), this command comes in handy to suspend only the current thread.

`show thread pause`

  This command shows the state of current thread suspension.

`set thread run`

  This command sets whether the current thread is allowed to run.

`show thread run`

  Show whether the current thread is allowed to run.

`set thread detach-suspend-count`

  This command sets the suspend count GDB will leave on a thread when detaching. This number is relative to the suspend count found by GDB when it notices the thread; use `set thread takeover-suspend-count` to force it to an absolute value.

`show thread detach-suspend-count`

  Show the suspend count GDB will leave on the thread when detaching.

`set thread exception-port`
`set thread excp`

  Set the thread exception port to which to forward exceptions. This overrides the port set by `set task exception-port` (see above). `set thread excp` is the shorthand alias.

`set thread takeover-suspend-count`

  Normally, GDB’s thread suspend counts are relative to the value GDB finds when it notices each thread. This command changes the suspend counts to be absolute instead.

`set thread default`
`show thread default`

  Each of the above `set thread` commands has a `set thread default` counterpart (e.g., `set thread default pause`, `set thread default exception-port`, etc.). The `thread default` variety of commands sets the default thread properties for all threads; you can then change the properties of individual threads with the non-default commands.

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