Remote SSH Commands - bash bind warning: line editing not enabled

Question

I am using bash 4.3.11(1) and have the following history plugin installed (via .bash_it):

# enter a few characters and press UpArrow/DownArrow
# to search backwards/forwards through the history
bind '"^[[A":history-search-backward'
bind '"^[[B":history-search-forward'

When I log in to an interactive session all is well but when I run remote commands via ssh host 'ls -als' for example, I see the following output:

: ssh host 'ls -als'
/home/ubuntu/.bash_it/plugins/enabled/history.plugin.bash: line 3: bind: warning: line editing not enabled
/home/ubuntu/.bash_it/plugins/enabled/history.plugin.bash: line 4: bind: warning: line editing not enabled

When I modify the history plugin with echo -e '\0033\0143' after each bind call I no longer get the warnings but my console is cleared. Not a huge drawback but it would be nice to know a cleaner way to suppress this for remote commands.

# Works, but annoyingly clears console
# enter a few characters and press UpArrow/DownArrow
# to search backwards/forwards through the history
bind '"^[[A":history-search-backward'
echo -e '\0033\0143'
bind '"^[[B":history-search-forward'
echo -e '\0033\0143'

score 33 · Answer 1 · answered Mar 22 '15 at 21:59

33

ssh host 'ls -als'

When you ask ssh to run a command on the remote system, ssh doesn't normally allocate a PTY (pseudo-TTY) for the remote session. You can run ssh with -t to force it to allocate a tty:

ssh -t host 'ls -als'

If you don't want to type that all the time, you could add this line to the ".ssh/config" file on your local host:

RequestTTY yes

Alternately, you could fix the ".bashrc" file on your remote system to avoid running commands that presume the session is interactive when it isn't. One way is to enclose the commands in a test that the session has a TTY:

if [ -t 1 ]
then
    # standard output is a tty
    # do interactive initialization
fi

answered Mar 22 '15 at 21:59

Kenster

8,009

1

Actually this answer is incorrect, see @alexander-vorobiev's answer below. – Ahmed Masud Jul 06 '19 at 19:41
Whether it is strictly correct or not, -t 1 does solve the problem for me. It does not affect the vim terminal session or external command, either. – Yongwei Wu May 19 '20 at 02:50
Looks like this is the "proper" way of detecting whether a shell is interactive. – IpsRich May 14 '21 at 06:57

score 8 · Accepted Answer · answered Sep 25 '18 at 03:28

8

Having an interactive session is not enough for bind to work. For instance emacs shell provides an interactive session which passes the if [ -t 1 ] test but it does not have the line editing so any binds in your ~/.bashrc will generate the warnings. Instead, you can check if the line editing is enabled by doing something like this (is there a simpler/better way?):

if [[ "$(set -o | grep 'emacs\|\bvi\b' | cut -f2 | tr '\n' ':')" != 'off:off:' ]]; then
  echo "line editing is on"
fi

answered Sep 25 '18 at 03:28

Alexander Vorobiev

196

This should be the correct answer – Ahmed Masud Jul 06 '19 at 19:41
4

The easier way would be to use [[ ${SHELLOPTS} =~ (vi|emacs) ]] && echo 'line-editing on' || echo 'line-editing off' – Ahmed Masud Jul 06 '19 at 19:48
less faff regex and more robust: if set -o | grep 'on$' | grep -q '^$vi\|emacs$\b'; then .... – hraban Mar 13 '20 at 16:53
FYI: Vim's terminal session works with bind, and its SHELLOPTS contains the string "emacs" (though I am not sure of the reason). – Yongwei Wu May 19 '20 at 02:58

score 6 · Answer 3 · answered Oct 07 '19 at 23:12

If there is no line editing, these bind commands themselves are harmless. Suppress the warnings:

bind '"^[[A":history-search-backward' 2>/dev/null
bind '"^[[B":history-search-forward'  2>/dev/null

This is somewhat inelegant, still it should work. Other answers don't agree about the best/sufficient test. My approach circumvents this. It doesn't scale well though. The two commands alone should not make a big difference; but if you had more, like dozens, then a proper conditional would probably be better.

Good point. Have an upvote. :-) – Jonathan Hartley Oct 08 '19 at 13:48 — Jonathan Hartley, Oct 08 '19 at 13:48

score 3 · Answer 4 · answered Oct 07 '19 at 22:07

3

Put the bind commands into an 'if' statement that checks whether the bash session allows line editing:

if [[ ${SHELLOPTS} =~ (vi|emacs) ]]; then
    bind '"^[[A":history-search-backward'
    bind '"^[[B":history-search-forward'
fi

answered Oct 07 '19 at 22:07

Jonathan Hartley

1,047

score 0 · Answer 5 · answered Dec 07 '23 at 09:24

0

I'd probably just test if my bash is interactive.

if [[ "$-" = *i* ]]
then
    debug "interactive mode"
    source ~/.bash_lib/bindings
else
    debug "non interactive mode"
fi

answered Dec 07 '23 at 09:24

ychaouche

481
2
9
21

Remote SSH Commands - bash bind warning: line editing not enabled

5 Answers5

Linked