Creating aliases beginning with + or -

Question

Most of the times, I find that I'm doing:

% chmod +x <file> #or +r or +w

So, I thought about creating an alias such that:

% alias +x='chmod +x' # or
% alias \+x='chmod +x' # or
% alias '+x'='chmod +x'

but it results in:

zsh: bad option: -x

Is there any other method to create the above alias? I currently am setting them up as

% alias c+x='chmod +x'

which is not what I had in mind.

Answer 1

Quoting + in that context has not desired effect effect because it only tells zle (zsh's command line editor) to take + literally. The command alias itself still recieves the string "+x" as first command line argument and thus tries to parse it as option.

If you pass the option -- to the alias command, everything after it will be used as an argument, even if it starts with an + or -. To use your example:

alias -- +x='chmod +x'
alias -- -x='chmod -x'

---

Note: Many - but not all - other tools behave similarly, zsh built-ins as well as external commands. For example:

% touch -negative
touch: invalid option -- 'n'
Try 'touch --help' for more information.
% touch -- -negative
% ls -negative
ls: invalid option -- 'e'
Try 'ls --help' for more information.
% ls -- -negative   
-negative
% rm -negative
rm: invalid option -- 'n'
Try 'rm ./-negative' to remove the file '-negative'.
Try 'rm --help' for more information.
% rm -- -negative 

Of course, you can also do as rm suggests and use ./-negative in most (all?) of these cases where paths are involved.

One notable exception is GNU echo. It is difficult to get it to print any options it recognizes without additional text. For example "-n":

% /bin/echo -n
% /bin/echo -- -n
-- -n
% /bin/echo -n -e '-n\n'
-n