.bash_logout commands get called with preexec repeating the last command line if logging out with CTRL+D

[davefx]

When logging out from an Ubuntu ssh session with CTRL+D in an empty command line, the preexec function gets called with the previous "$1" while executing the line /usr/bin/clear_console -q from ~/.bash_logout.
For example:

$ ssh localhost
davefx@localhost's password: 
Welcome to Ubuntu 16.04 LTS (GNU/Linux 4.4.0-31-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

91 packages can be updated.
0 updates are security updates.

Last login: Mon Jul 25 07:59:53 2016 from 127.0.0.1
davefx@localhost:~ $ preexec() { echo «$1»; sleep 3; }
davefx@localhost:~ $ echo Hello
«echo Hello»
Hello
davefx@laetus:~ $ logout
«echo Hello»
Connection to localhost closed.
davefx@laetus:~ $ 

(The logout was generated pressing CTRL+D)

[rcaloras]

@davefx thanks for reporting! Giving it a look.

[jombooth]

I have an idea for fixing this; the output of fc -l (a replacement for history, see #53) gives a number for each command, like this:
1048 set +x
1049 ls
1050 ld
1051 fc -l 0

if we store the last processed command number, then we can skip preexec in the case it hasn't changed.

[dimo414]

Would it make sense to replace the existing short-circuit checks in __bp_preexec_invoke_exec with this check? Put another way is it the case that preexec should fire if-and-only-if the command number has changed?

[rcaloras]

I've considered this before. @jombooth What about the case where we have duplicate commands and ignoredups set? e.g. You enter the same command twice. History will not change (no increment in number) but we should invoke preexec.

[JeffFaer]

What about comparing this_command to BASH_COMMAND in __bp_preexec_invoke_exec?

$ tmux
tmux $ foo() {
> if [[ -z $i ]]; then
> i=0
> else
> ((i++))
> fi
> (set -o posix; set) > ~/env.$i
> }
tmux $ preexec_functions+=(foo)
tmux $ echo 1 2 3
tmux $ <CTRL + D>
$ grep 'this_command' ~/env.0 ~/env.1
~/env.0:this_command='echo 1 2 3'
~/env.1:this_command='echo 1 2 3'
$ diff ~/env.0 ~/env.1
4,5c4,5
< BASH_ARGC=()
< BASH_ARGV=()
---
> BASH_ARGC=([0]="1")
> BASH_ARGV=([0]="/home/jeffrey/.bash_logout")
7c7
< BASH_COMMAND='echo 1 2 3'
---
> BASH_COMMAND='[ "$SHLVL" = 1 ]'
9,10c9,10
< BASH_LINENO=([0]="67" [1]="10")
< BASH_SOURCE=([0]="main" [1]="/home/jeffrey/src/bash-preexec/bash-preexec.sh")
---
> BASH_LINENO=([0]="213" [1]="5" [2]="11")
> BASH_SOURCE=([0]="main" [1]="/home/jeffrey/src/bash-preexec/bash-preexec.sh" [2]="/home/jeffrey/.bash_logout")
26c26
< FUNCNAME=([0]="foo" [1]="__bp_preexec_invoke_exec")
---
> FUNCNAME=([0]="foo" [1]="__bp_preexec_invoke_exec" [2]="source")
103c103
< __bp_last_argument_prev_command=
---
> __bp_last_argument_prev_command=3
723c723
< i=0
---
> i=1