mjhjmtu

I read from this answer that the more reliable way to test whether a command exist is to use $ command -v:

if command -v given-command > /dev/null 2>&1; then
 echo given-command is available
else
 echo given-command is not available
fi

I have used this command to get a listing of all valid commands in my $PATH:

get_all_cmds() sort 

It works, but in the pager I can read this command:

/home/user/bin/README.md

This is not the path to a command, but a readme file that I wrote in my bin/ directory to document why some scripts were there.

It turns out that $ command -v /home/user/bin/README.md returns vim, and more importantly exits with the code 0. This is due to this suffix alias which I wrote in ~/.zshrc:

alias -s md,markdown,txt,html,css=vim

I think that, because of it, when $ command tries to execute /home/user/bin/README.md, instead of failing, it expands the suffix alias into vim /home/user/bin/README.md, which is a valid command.

I found a solution here. It temporarily removes all aliases. Adapted to my issue with suffix aliases, it gives something like:

 # save suffix aliases
 local aliases_save
 aliases_save=$(alias -L -s)

 # remove suffix aliases
 unalias -s -m '*'

 # do what you have to do
 ....

 # restore suffix aliases
 eval "$aliases_save"

It seems to work, but I wondered whether a simpler solution existed, which would also protect the function from regular aliases. In $ man zshbuiltins, I read this about the -U option which can be passed to the autoload builtin:

With the -U flag, alias expansion is suppressed when the function is loaded.

It seems to be what I wanted. I made the get_all_cmds function autoloadable so that I could load it with autoload -U thinking that the -U option would suppress any alias expansion.
To do so, in ~/.zshrc, I have added the directory ~/.zsh/my_func/ inside $fpath:

fpath=( $HOME/.zsh/my_func/ $fpath )

Then, in ~/.zsh/my_func/get_all_cmds, I wrote the body of the function:

emulate -L zsh
unsetopt nomatch

for dir in $(tr ':' ' ' <<<"$PATH"); do
 for cmd in $dir/*; do
 if command -v "$cmd" >/dev/null 2>&1; then
 echo "$cmd"
 fi
 done
done | sort | less

Finally, in ~/.zshrc, I made the function autoloadable:

autoload -Uz get_all_cmds

But when I invoke the get_all_cmds function on the shell command line, I can still find /home/user/bin/README.md in the pager.

I thought that maybe the code contained a syntax error, so I tried with a simpler code:

fpath=( ~/.zsh/my_func/ $fpath ) && 
mkdir -p ~/.zsh/my_func/ && 
echo 'ls' >~/.zsh/my_func/my_colored_ls && 
alias ls='ls --color' && 
autoload -Uz my_colored_ls && 
my_colored_ls

Here, the code works as expected, because the output printed by $ ls is not colorized, even though the regular alias ls='ls --color' is defined.
On the other hand, if I restart a new shell and I remove the -U option which was passed to autoaload:

fpath=( ~/.zsh/my_func/ $fpath ) && 
mkdir -p ~/.zsh/my_func/ && 
echo 'ls' >~/.zsh/my_func/my_colored_ls && 
alias ls='ls --color' && 
autoload -z my_colored_ls && 
my_colored_ls

This time, the output of $ ls is colorized.
So, the syntax of the commands seems correct since, here, -U is able to suppress the expansion of alias ls='ls --color'.

I also tried with a global alias (alias -g L=' | less'):

fpath=( ~/.zsh/my_func/ $fpath ) && 
mkdir -p ~/.zsh/my_func/ && 
echo 'echo "should be read in pager" L' >~/.zsh/my_func/my_test && 
alias -g L='| less' && 
autoload -Uz my_test && 
my_test

And again, the -U option correctly suppresses the expansion of the global alias, because instead of reading should be read in pager inside the $ less pager, should be read in pager L is printed on the terminal.

Why does the -U option of the autoload zsh builtin suppresses the expansion of regular and global aliases, but not the expansion of suffix aliases?