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@kopischke
Last active June 4, 2022 00:53
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Automatically add completion functions for aliases
# Automatically add completion for all aliases to commands having completion functions
function alias_completion {
local namespace="alias_completion"
# parse function based completion definitions, where capture group 2 => function and 3 => trigger
local compl_regex='complete( +[^ ]+)* -F ([^ ]+) ("[^"]+"|[^ ]+)'
# parse alias definitions, where capture group 1 => trigger, 2 => command, 3 => command arguments
local alias_regex="alias ([^=]+)='(\"[^\"]+\"|[^ ]+)(( +[^ ]+)*)'"
# create array of function completion triggers, keeping multi-word triggers together
eval "local completions=($(complete -p | sed -Ene "/$compl_regex/s//'\3'/p"))"
(( ${#completions[@]} == 0 )) && return 0
# create temporary file for wrapper functions and completions
rm -f "/tmp/${namespace}-*.tmp" # preliminary cleanup
local tmp_file; tmp_file="$(mktemp "/tmp/${namespace}-${RANDOM}XXX.tmp")" || return 1
local completion_loader; completion_loader="$(complete -p -D 2>/dev/null | sed -Ene 's/.* -F ([^ ]*).*/\1/p')"
# read in "<alias> '<aliased command>' '<command args>'" lines from defined aliases
local line; while read line; do
eval "local alias_tokens; alias_tokens=($line)" 2>/dev/null || continue # some alias arg patterns cause an eval parse error
local alias_name="${alias_tokens[0]}" alias_cmd="${alias_tokens[1]}" alias_args="${alias_tokens[2]# }"
# skip aliases to pipes, boolean control structures and other command lists
# (leveraging that eval errs out if $alias_args contains unquoted shell metacharacters)
eval "local alias_arg_words; alias_arg_words=($alias_args)" 2>/dev/null || continue
# avoid expanding wildcards
read -a alias_arg_words <<< "$alias_args"
# skip alias if there is no completion function triggered by the aliased command
if [[ ! " ${completions[*]} " =~ " $alias_cmd " ]]; then
if [[ -n "$completion_loader" ]]; then
# force loading of completions for the aliased command
eval "$completion_loader $alias_cmd"
# 124 means completion loader was successful
[[ $? -eq 124 ]] || continue
completions+=($alias_cmd)
else
continue
fi
fi
local new_completion="$(complete -p "$alias_cmd")"
# create a wrapper inserting the alias arguments if any
if [[ -n $alias_args ]]; then
local compl_func="${new_completion/#* -F /}"; compl_func="${compl_func%% *}"
# avoid recursive call loops by ignoring our own functions
if [[ "${compl_func#_$namespace::}" == $compl_func ]]; then
local compl_wrapper="_${namespace}::${alias_name}"
echo "function $compl_wrapper {
(( COMP_CWORD += ${#alias_arg_words[@]} ))
COMP_WORDS=($alias_cmd $alias_args \${COMP_WORDS[@]:1})
(( COMP_POINT -= \${#COMP_LINE} ))
COMP_LINE=\${COMP_LINE/$alias_name/$alias_cmd $alias_args}
(( COMP_POINT += \${#COMP_LINE} ))
$compl_func
}" >> "$tmp_file"
new_completion="${new_completion/ -F $compl_func / -F $compl_wrapper }"
fi
fi
# replace completion trigger by alias
new_completion="${new_completion% *} $alias_name"
echo "$new_completion" >> "$tmp_file"
done < <(alias -p | sed -Ene "s/$alias_regex/\1 '\2' '\3'/p")
source "$tmp_file" && rm -f "$tmp_file"
}; alias_completion
@kopischke
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Originally created as an answer to this question on Super User. Adapted from this answer on Stack Overflow, with input from the comments and this Ubuntu Forums discussion thread. All credits to the original posters – all bugs mine.

@raineorshine
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raineorshine commented Mar 22, 2020

I'm guessing this gist is behind the Super User answer.

  • Here's the script from SU at time of writing. I'll delete this once @kopischke updates the gist.

Still very useful 8 years later :)

@kopischke
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Done, thanks for the nudge, @raineorshine; I left the bash universe years ago, I must admit I more or less forgot about this.

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