bash expand cd with shortcuts like zsh - bash

Question

Is it possible in bash to expand something like
cd /u/lo/b<hit tab>
to
cd /usr/local/bin
?

Answer 1

Sorry I couldn't post earlier, I was held at work, and the bind function was more issue-prone than I first thought.
Here is what I came up with :
Bind the following script :
#!/bin/bash
#$HOME/.bashrc.d/autocomplete.sh
autocomplete_wrapper() {
BASE="${READLINE_LINE% *} " #we save the line except for the last argument
[[ "$BASE" == "$READLINE_LINE " ]] && BASE=""; #if the line has only 1 argument, we set the BASE to blank
EXPANSION=($(autocomplete "${READLINE_LINE##* }"))
[[ ${#EXPANSION[#]} -gt 1 ]] && echo "${EXPANSION[#]:1}" #if there is more than 1 match, we echo them
READLINE_LINE="$BASE${EXPANSION[0]}" #the current line is now the base + the 1st element
READLINE_POINT=${#READLINE_LINE} #we move our cursor at the end of the current line
}
autocomplete() {
LAST_CMD="$1"
#Special starting character expansion for '~', './' and '/'
[[ "${LAST_CMD:0:1}" == "~" ]] && LAST_CMD="$HOME${LAST_CMD:1}"
S=1; [[ "${LAST_CMD:0:1}" == "/" || "${LAST_CMD:0:2}" == "./" ]] && S=2; #we don't expand those
#we do the path expansion of the last argument here by adding a * before each /
EXPANSION=($(echo "$LAST_CMD*" | sed s:/:*/:"$S"g))
if [[ ! -e "${EXPANSION[0]}" ]];then #if the path cannot be expanded, we don't change the output
echo "$LAST_CMD"
elif [[ "${#EXPANSION[#]}" -eq 1 ]];then #else if there is only one match, we output it
echo "${EXPANSION[0]}"
else
#else we expand the path as much as possible and return all the possible results
while [[ $l -le "${#EXPANSION[0]}" ]]; do
for i in "${EXPANSION[#]}"; do
if [[ "${EXPANSION[0]:$l:1}" != "${i:$l:1}" ]]; then
CTRL_LOOP=1
break
fi
done
[[ $CTRL_LOOP -eq 1 ]] && break
((l++))
done
#we add the partial solution at the beggining of the array of solutions
echo "${EXPANSION[0]:0:$l} ${EXPANSION[#]}"
fi
}
with the following command :
source "$HOME/.bashrc.d/autocomplete.sh"
bind -x '"\t" : autocomplete_wrapper'
Output :
>$ cd /u/lo/b<TAB>
>$ cd /usr/local/bin
>$ cd /u/l<TAB>
/usr/local /usr/lib
>$ cd /usr/l
The bind line could be added to your ~/.bashrc file, doing something like this :
if [[ -s "$HOME/.bashrc.d/autocomplete.sh" ]]; then
source "$HOME/.bashrc.d/autocomplete.sh"
bind -x '"\t" : autocomplete_wrapper'
fi
(taken from this answer)
Furthermore, I would strongly advise against binding this command to your Tab key as it would override the default autocomplete.
Note: In some cases, this will misbehave, for isntance if you try to autocomplete "/path/with spaces/something", as the last argument to complete is determined by ${READLINE_LINE##* }. If this is an issue in your case, you should code a function that returns the last argument of a line when considering quotes
Feel free to ask for further clarification, and I welcome any suggestion to improve this script

Answer 2

I have come up with an alternative solution that does not break existing bash
completion rules in other places.
The idea is to append a wildcard (asterisk) to every element of the path and
invoke normal bash completion process from there. So when user types
/u/lo/b<Tab> my function substitutes that with /u*/lo*/b* and invokes bash
completion as usual.
To enable the described behavior source this file from your
~/.bashrc. Supported features are:
Special characters in completed path are automatically escaped if present
Tilde expressions are properly expanded (as per bash documentation)
If user had started writing the path in quotes, no character escaping is
applied. Instead the quote is closed with a matching character after expanding
the path.
If bash-completion package is already in use, this code will safely override
its _filedir function. No extra configuration is required.
Watch a demo screencast to see this feature in action:
Full code listing below (you should check the GitHub repo for latest updates though):
#!/usr/bin/env bash
#
# Zsh-like expansion of incomplete file paths for Bash.
# Source this file from your ~/.bashrc to enable the described behavior.
#
# Example: `/u/s/a<Tab>` will be expanded into `/usr/share/applications`
#
# Copyright 2018 Vitaly Potyarkin
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Take a single incomplete path and fill it with wildcards
# e.g. /u/s/app/ -> /u*/s*/app*
#
_put_wildcards_into_path() {
local PROCESSED TILDE_EXPANSION
PROCESSED=$( \
echo "$#" | \
sed \
-e 's:\([^\*\~]\)/:\1*/:g' \
-e 's:\([^\/\*]\)$:\1*:g' \
-e 's:\/$::g' \
-e 's:^\(\~[^\/]*\)\*\/:\1/:' \
-Ee 's:(\.+)\*/:\1/:g' \
)
eval "TILDE_EXPANSION=$(printf '%q' "$PROCESSED"|sed -e 's:^\\\~:~:g')"
echo "$TILDE_EXPANSION"
}
#
# Bash completion function for expanding partial paths
#
# This is a generic worker. It accepts 'file' or 'directory' as the first
# argument to specify desired completion behavior
#
_complete_partial() {
local WILDCARDS ACTION LINE OPTION INPUT UNQUOTED_INPUT QUOTE
ACTION="$1"
if [[ "_$1" == "_-d" ]]
then # _filedir compatibility
ACTION="directory"
fi
INPUT="${COMP_WORDS[$COMP_CWORD]}"
# Detect and strip opened quotes
if [[ "${INPUT:0:1}" == "'" || "${INPUT:0:1}" == '"' ]]
then
QUOTE="${INPUT:0:1}"
INPUT="${INPUT:1}"
else
QUOTE=""
fi
# Add wildcards to each path element
WILDCARDS=$(_put_wildcards_into_path "$INPUT")
# Collect completion options
COMPREPLY=()
while read -r -d $'\n' LINE
do
if [[ "_$ACTION" == "_directory" && ! -d "$LINE" ]]
then # skip non-directory paths when looking for directory
continue
fi
if [[ -z "$LINE" ]]
then # skip empty suggestions
continue
fi
if [[ -z "$QUOTE" ]]
then # escape special characters unless user has opened a quote
LINE=$(printf "%q" "$LINE")
fi
COMPREPLY+=("$LINE")
done <<< $(compgen -G "$WILDCARDS" "$WILDCARDS" 2>/dev/null)
return 0 # do not clutter $? value (last exit code)
}
# Wrappers
_complete_partial_dir() { _complete_partial directory; }
_complete_partial_file() { _complete_partial file; }
# Enable enhanced completion
complete -o bashdefault -o default -o nospace -D -F _complete_partial_file
# Optional. Make sure `cd` is autocompleted only with directories
complete -o bashdefault -o default -o nospace -F _complete_partial_dir cd
# Override bash-completion's _filedir (if it's in use)
# https://salsa.debian.org/debian/bash-completion
_filedir_original_code=$(declare -f _filedir|tail -n+2)
if [[ ! -z "$_filedir_original_code" ]]
then
eval "_filedir_original() $_filedir_original_code"
_filedir() {
_filedir_original "$#"
_complete_partial "$#"
}
fi
# Readline configuration for better user experience
bind 'TAB:menu-complete'
bind 'set colored-completion-prefix on'
bind 'set colored-stats on'
bind 'set completion-ignore-case on'
bind 'set menu-complete-display-prefix on'
bind 'set show-all-if-ambiguous on'
bind 'set show-all-if-unmodified on'