how to expand aliases inline in bash?

Question

Is there a way to expand aliases inline in bash?

$bash>alias ll='ls -l '
$bash>ll<tab>
$bash>ls -l 

Answer 1

You can press Ctrl-Alt-e to perform the readline function shell-expand-line which will do alias, history and word expansions. Note that on some keyboards Meta is not Alt. You might need to press Esc then Ctrl-e

The functions alias-expand-line and history-and-alias-expand-line are not bound by default, but you can bind them by adding lines similar to the following to your ~/.inputrc file.

"\e\C-l": alias-expand-line

which would make Ctrl-Alt-l (lower case "ell") perform only alias expansion.

Answer 2

For people having zsh & Oh My ZSH installed looking for a simple solution, globalias might be your friend

Expands all glob expressions, subcommands and aliases (including global).

# .zsrc:
alias S="sudo systemctl"

$ S<space>
# expands to:
$ sudo systemctl

to install just add "globalias" to you .zshrc plugin list

plugins=(... globalias)

Then just press SPACE to trigger the expansion of a command you've written.

If you only want to insert a space without expanding the command line, press CTRL+SPACE

Answer 3

This does not work. But I'm guessing/hoping something like this can be done to do what you want to do. You would have to use your own completion script. This is how you make one:

_ll()
{
     COMPREPLY=(ls -l)
     #The next line does not work. I just hope there were a way to replace that word
     COMP_WORDS[COMP_CWORD-1]="ls -l"
}
complete -F _ll ll

Now source the full bash_completion file(http://caliban.org/bash) and put the above mentioned script in a file inside bash_completion.d directory that the script you get from the url references. Let me know if it doesn't work.

Thanks.

Answer 4

While looking into this I found this post https://stackoverflow.com/a/42699460

What stood out to me is that, according to the Bash Manual

Aliases are expanded when a function definition is read, not when the function is executed, because a function definition is itself a command

Testing that

eval "fn() {
  $AN_ALIAS
}"

declare -f blah

Then when I do

> alias analias='echo hello'
> alias another='analias from another alias'
> AN_ALIAS=another . ./test.sh 
fn () 
{ 
    echo hello from another alias
}

Nice, but

> alias analias='bar'
> alias another='echo foo analias'
> AN_ALIAS=another . ./test.sh
fn () 
{ 
    echo foo analias
}
foo analias

So it only expands the inner alias if it is the first. This is expected, since even if you run another in your terminal it'll print foo analias

If you really need to expand them all (and there's prob a better way to do this since this will prob not work in a lot of situations)

expand_alias() {
  local myalias="$1"
  local match=''
  match=$(
    eval "inner() {
      $myalias
    }"
    declare -f inner | sed 's/^[ \t]*//' |
      grep -vF -e 'inner ()' -e '{' -e '}'
  )

  if [[ $match != "$myalias" ]]; then
    while read -d ' ' -r item; do
      expand_alias "$item"
    done <<<"$match "
  else
    printf %s "$match "
  fi
}

expand_alias "$AN_ALIAS"

and now

> alias another && alias analias && AN_ALIAS=another . ./test.sh 
alias another='echo foo analias'
alias analias='bar'
echo foo bar 

sed to remove leading white space and grep to only include lines that do not match exactly inner (), { or }

And non of this works if you're not sourcing the script

Answer 5

This actually might be a much simpler way to do what you're trying to (bashversion >= 4.2.29):

shopt -s direxpand
shopt -s expand_aliases

shopt's man page: https://www.gnu.org/software/bash/manual/html_node/The-Shopt-Builtin.html