Way to bypass .zshrc on login

zsh

I'm enjoying learning ZSH, but one thing's bugging me. If I put something in my .zshrc that renders the shell useless (I'm playing with something that affects the way the keyboard is interpreted), then I could end up not being able to fix it unless I can bypass my zshrc on login.

Is there a way?

Best Answer

Contrary to bash, zsh doesn't read .zshrc when running commands over ssh. So if you mess up your zshrc, you can always do:

ssh machine mv .zshrc .zshrc.disabled

from another machine to put your .zshrc out of the way.

If you want to test a zshrc, you can put it in another directory and run zsh as:

ZDOTDIR=/that/dir zsh

to run zsh with that .zshrc (or .zshenv or .zprofile/.zlogin/.zlogout with zsh -l).

You can also login with that ZDOTDIR over ssh with:

ssh -t machine ZDOTDIR=/that/dir zsh -l

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In the 21st century, especially if you're targeting machines that are likely to have bash or zsh, you can count on type being available. (It didn't exist in extremely old unices, as in, from the 1970s or early 1980s.) You can't count on its output meaning anything, but you can count on its returning 0 if there is a command by that name and nonzero otherwise.

which isn't standard and is unreliable in practice. type is the recommended alternative. whereis suffers from the same problems as which and is less common. whence is specific to ksh and zsh.

When that's possible, it would be more reliable to test the existence of a command and test whether its behavior looks reasonable. For example, test the presence of a suitable version of bash by running bash -c 'somecommand', e.g.

# Test for the `-v` operator (which appeared in bash 4.2)
if bash -c 'test -v HOME' 2>/dev/null; then …

Today you can count on almost everything in the Singe UNIX specification version 2 (except for exotic stuff like Fortran and SCCS, which are optional anyway). You can count on most of version 3, too, but this isn't completely implemented everywhere yet. Version 4 support is sketchier. If you're going to read these specs, I recommend reading version 3, which is a lot more readable and less ambiguous than version 2.

For examples as to how to detect system specificities, look at autoconf and at configure scripts of various software.

See also Resources for portable shell programming for more tips.

Zsh autocomplete directory

Not exactly what you asked but I use s to run scripts. So for example if I have a file ~/Scripts/run-stuff.sh I can type s run-stuff.sh and it will run the script. It will also do tab-completion of the script name. The only thing it doesn't do is handle sub-directories in the scripts directory.

# Completion for s (scripts)
_s_comp() {
    if [ $OS = "mac" ]; then
        local LS=gls;
    else
        local LS=ls;
    fi
    reply=(`$LS --ignore-backups $HOME/Scripts/`);
}

compctl -K _s_comp s

It's possible that you may also need an alias like alias s="$HOME/Scripts

Edit: note that this will work regardless of what directory you are currently in.

Best Answer

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