Background
----------

I'm running a larger one-line command. It is unexpectedly outputting (twice per iteration) the following:

> 
> \_\_bp\_preexec\_invoke\_exec "$\_"
> 
> 
> 

Here is the pared down command (removed other activity in loop):

```
for i in `seq 1 3`; do sleep .1 ; done

```

*note: after i have played with this a few times it inexplicably stops printing the unexpected output*

What I've tried
---------------

* If I remove `sleep .5` I do not get the unexpected output
* If I simply run `sleep .5` the prompt returns but there is no output
* I have googled around for `__bp_preexec_invoke_exec`, but I am unable to determine how it applies to what I'm doing

Question
--------

What is *\_\_bp\_preexec\_invoke\_exec "$\_"?*

How can I run this without the unwanted output?

---

More info on solution thanks to @gina2x:
----------------------------------------

Here is the output of `declare -f | grep preexec`

```
    preexec_functions+=(preexec);
    __bp_preexec_interactive_mode="on"
__bp_preexec_invoke_exec ()
    if [[ -z "$__bp_preexec_interactive_mode" ]]; then
            __bp_preexec_interactive_mode="";
        __bp_preexec_interactive_mode="";
    local preexec_function;
    local preexec_ret_value=0;
    for preexec_function in "${preexec_functions[@]}";
        if type -t "$preexec_function" > /dev/null; then
            $preexec_function "$this_command";
            preexec_ret_value="$?";
    __bp_set_ret_value "$preexec_ret_value" "$__bp_last_argument_prev_command"
    if [[ -z "${iterm2_ran_preexec:-}" ]]; then
        __iterm2_preexec "";
    iterm2_ran_preexec="";
__iterm2_preexec ()
    iterm2_ran_preexec="yes";

```

I see in there a lot of "iterm2" information (I'm on a Mac and using iTerm2.app). 

**In fact, when I try to reproduce using Terminal.app, I am *unable to reproduce* the unexpected output**.

Excellent sleuthing with `declare -f` - thank you!