Comments on From XON/XOFF to Forward Incremental Search
Peter said:
# bash: a small cantrip to disable ixon before readline and
# turning it on again afterwards during command execution
# (assuming trap DEBUG not in use)
#
# inspired by and to extend the article on ixon on
# susam.net/blog/from-xon-xoff-to-forward-incremental-search.html
unset _IXON
# before readline, issue stty -ixon to permit use of ^s for
# incremental search, then reenable it for the next command
PROMPT_COMMAND="$PROMPT_COMMAND; : _IXONOFF"
function _TRAP_DEBUG {
if [ "$BASH_COMMAND" = ": _IXONOFF" ]; then
# about to enter readline, thus turn off ixon
stty -ixon
# and reenable it for the command from readline
_IXON=1
elif [ "$_IXON" = "1" ]; then
# readline finished, we are about to run its input as command
stty ixon
unset _IXON
fi
}
trap _TRAP_DEBUG DEBUG
echo "test it by ^s/^q the output during the run of the next command"
echo "(use ^c to end)"
find / -xdev 2>/dev/null
echo test ^s incremental search during readline:
: ...
: enjoy,
: Peter
Peter said:
With respect to the cantrip, the below line
in ~/.inputrc might be preferable, as it remaps
(forward) i-search to ctrl+^ for all programs
using GNU-readline.
"\C-^": forward-search-history
And if you edit ~/.inputrc, consider adding a mapping
for kill-region, in my case using an en-US keymap, its
esc ctrl+@, and permits to
move/copy/erase character regions together
with ctrl+y
and ctrl+x ctrl+x.
"\e\C-@": kill-region
'nough said,
Peter
Susam Pal said:
Thank you, Peter, for your comments. It took a few changes to get
your Bash script to work properly in my shell. Since I do not
have PROMPT_COMMAND set in my shell, the evaluation of
the following prompt command
PROMPT_COMMAND="$PROMPT_COMMAND; : _IXONOFF"was causing this error:
bash: PROMPT_COMMAND: line 0: syntax error near unexpected token `;' bash: PROMPT_COMMAND: line 0: `; : _IXONOFF'
Here is how I modified your script to check
if PROMPT_COMMAND is set before expanding it. If it is
not set we use the null command : before the semicolon
separator.
unset _IXON
PROMPT_COMMAND="${PROMPT_COMMAND:-:}; : _IXONOFF"
function _TRAP_DEBUG {
if [ "$BASH_COMMAND" = ": _IXONOFF" ]; then
stty -ixon
_IXON=1
elif [ "$_IXON" = "1" ]; then
stty ixon
unset _IXON
fi
}
trap _TRAP_DEBUG DEBUG
To test this, we can add the above script to ~/.bashrc,
then run something like ping localhost and confirm
that ctrl+s pauses the output, whereas in the
shell ctrl+s performs forward incremental
search.
KDK said:
This was a very interesting read! I have personally solved this by using fuzzy finder, which gives a menu/search box with a selection instead of the simplistic string matching of ctrl+r.
If you are a heavy terminal user, I would recommend looking into https://wiki.archlinux.org/title/fzf. I see the built-in search being especially useful on remote/shared machines, where you do not necessarily want to install stuff.
The XON/XOFF feature actually seems quite useful for terminals without scrollback. Or for when you don't have a mouse. Hopefully I'll remember it. Thank you very much for your article!
Orev said:
This is a great explanation, especially the part describing how control codes are mapped to their corresponding letters. I always felt there was probably some logic to it, but the idea never fully materialized into something I thought to investigate. Learning about how to disable XON/OFF is more like a bonus.
Loomx said:
As an alternative, use ctrl+f for "forward-inc-search"; it's easier to remember (mnemonic) and means you can still use ctrl+s or ctrl+q for flow control as normal. For example, in Bash: