Autoexpanding aliases with readline; the story of suod

Have you ever typed suod instead of sudo? I do that quite often; maybe I am becoming typing dixleysc, who knows.

Context: Debian Gnu/Linux using the bash command line shell and bash-completion.

The problem is: execute sudo when suod is typed.

  • A trivial solution would be to put in place a shell alias:

    alias suod='sudo'
    

    it makes sense, but command line completion will not be available.

    This can be worked around by setting up the same completion function of the aliased command for the aliasing one:

    source /usr/share/bash-completion/completions/sudo
    complete -F _sudo suod
    

    this is nice, but not enough for me, it is still lacking “cross-alias” history completion in case the wrong version is typed only sometime; and history completion is the greatest thing since... you know.

  • Or, readline key bindings can be abused to implement an auto-correction functionality at the shell level. The problem is about a typo, after all.

    For that purpose this variant of key bindings will be used:

    KEYSEQ: STRING_MACRO
    

    Either the following can be put in ~/.inputrc:

    "suod": "\C-vsudo"
    

    or the bash builtin command bind can be invoked from ~/.bashrc:

    bind '"suod": "\C-vsudo"'
    

    Now every time the suod key sequence is typed in, it will be replaced automatically with sudo on the command line.

    The \C-v sequence calls the quoted-insert function which tells readline that the following character —namely s— has to be taken verbatim, this is needed to avoid that the s key is considered as the start of a macro expansion itself messing up the end result.

    This solution is good enough for me, as I get history completion.

    Maybe there could be downsides too:

    1. the expansion happens at any point in the line;
    2. there could be conflicts if many of these typo-fixing-hacks share letters one another; the possible issues could be alleviated by prefixing each character in the macro string with the sequence for quoted-insert.

SIDE NOTE

Unrelated, but while googling around I've found out how to have aliases executed in a sudo context by using this alias:

alias sudo='sudo '

Check out the Aliases section of the bash manual for the complete explanation.


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