How to Temporarily Bypass an Alias in tcsh

aliasshelltcsh

I am using tcsh. bash and zsh and other suggestions won't help here.

I have several aliases that are named the same thing as another command, so if I did unalias it, typing the same thing would now do something different.

Most of the time I want the aliased command, which is why I have them. However, sometimes I want the unaliased command.

Without actually unaliasing and redefining the command, is there a simple way to tell tcsh to use the unaliased command instead?

For example, vi is aliased to vim, but sometimes I want to just use vi. cd is aliased to change my window title, but sometimes I want to leave it alone.

Obviously I could type /usr/bin/vi but since cd is a shell built-in command, there is no equivalent. Is there a general solution?

Best Answer

You can use a backslash:

% alias ls ls -a
% ls
# ls -a output here
% \ls
# plain ls output here

For shell builtins, there turns out to be a gotcha: a leading backslash prevents both aliases and builtins from being used, but an internal backslash suppresses aliasing only.

% alias cd pushd
% cd /tmp
/tmp /tmp 
% c\d
% dirs
~ /tmp

(I'm tempted to call that another argument against using the csh family of shells.)

Related Solutions

Bash Script – Why Can’t I Use Alias in Script Even If Defined Above?

Simply don't use aliases in scripts. It makes little sense to use a feature designed for interactive use in scripts. Instead, use functions:

somecommand () {
    ls -alF
}

Functions are much more flexible than aliases. The following would overload the usual ls with a version that always does ls -F (arguments are passed in $@, including any flags that you use), pretty much as the alias alias ls="ls -F" would do:

ls () {
    command ls -F "$@"
}

The command here prevents the shell from going into an infinite recursion, which it would otherwise do since the function is also called ls.

An alias would never be able to do something like this:

select_edit () (
    dir=${1:-.}
    if [ ! -d "$dir" ]; then
        echo 'Not a directory' >&2
        return 1
    fi
    shopt -s dotglob nullglob
    set --
    for name in "$dir"/*; do
        [ -f "$name" ] && set -- "$@" "$name"
    done
    select file in "$@"; do
        "${EDITOR:-vi}" "$file"
        break
    done
)

This creates the function select_edit which takes directory as an argument and asks the user to pick a file in that directory. The picked file will be opened in an editor for editing.

The bash manual contains the statement

For almost every purpose, aliases are superseded by shell functions.

Best Answer

Related Solutions

Bash Script – Why Can’t I Use Alias in Script Even If Defined Above?

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