DOKK / manpages / debian 12 / fiu-utils / fiu-ctrl.1.en
fiu-ctrl(1) General Commands Manual fiu-ctrl(1)

fiu-ctrl - a script to remote control programs using libfiu

fiu-ctrl [options] PID [PID ...]

fiu-ctrl is a script to enable/disable failure points in running programs that are using libfiu(3).

Programs are usually launched using fiu-run(1), which enables libfiu's remote control capabilities without the need to modify the program's code.

For additional documentation, go to the project's website at

Run the given libfiu remote control command before executing the program (see below for reference).
Set the default prefix for remote control over named pipes. Defaults to "$TMPDIR/fiu-ctrl", or "/tmp/fiu-ctrl" if "$TMPDIR" is not set, which is the usually correct for programs launched using fiu-run(1).

Remote control commands are of the form "command param1=value1,param2=value2". Valid commands are:

'enable name=NAME'
Enables the NAME failure point unconditionally.
'enable_random name=NAME,probability=P'
Enables the NAME failure point with a probability of P.
'disable name=NAME'
Disables the NAME failure point.

All of the enable* commands can also optionally take failnum and failinfo parameters, analogous to the ones taken by the C functions.

The following command will tell the process running with PID 12345 to enable the failure point posix/io/read with a 25% of probability to fail, and the failure point libc/mm/malloc with a 5% of probability to fail:

fiu-ctrl -c 'enable_random name=posix/io/*,probability=0.25' \

-c 'enable_random name=libc/mm/*,probability=0.05' 12345

And the following will tell the same process to disable the previously enabled failure point posix/io/read:

fiu-ctrl -c 'disable name=posix/io/read' 12345

libfiu(3), fiu-run(1).

If you want to report bugs, or have any questions or comments, just let me know at For more information about libfiu, you can go to