How to use precommand modifiers `-` ?

How to use precommand modifiers `-` ?

[andme]

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```-

The command is executed with a ‘-’ prepended to its argv[0] string. 

```


As a non-native speaker of English, I'm confused about this.
Can anyone give me some examples?


Thanks

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Re: How to use precommand modifiers `-` ?

[Roman Perepelitsa]

On Thu, May 13, 2021 at 12:56 PM andme <15991987063@163.com> wrote:
>
> ```-
>
> The command is executed with a ‘-’ prepended to its argv[0] string.
>
> ```
>
> As a non-native speaker of English, I'm confused about this.
> Can anyone give me some examples?

Here's an example:

    % zsh -fc 'print -r -- $0'
    zsh

    % - zsh -fc 'print -r -- $0'
    -zsh

Here $0 gives us argv[0].

Roman.

Re: How to use precommand modifiers `-` ?

[Vincent Bernat]

 ❦ 13 mai 2021 13:04 +02, Roman Perepelitsa:

>> ```-
>>
>> The command is executed with a ‘-’ prepended to its argv[0] string.
>>
>> ```
>>
>> As a non-native speaker of English, I'm confused about this.
>> Can anyone give me some examples?
>
> Here's an example:
>
>     % zsh -fc 'print -r -- $0'
>     zsh
>
>     % - zsh -fc 'print -r -- $0'
>     -zsh
>
> Here $0 gives us argv[0].

To complete your answer, this is used by shells to know if they should
use a login session or not. Some shells, including Zsh, can also take an
option for that (-l), but it's not an universal option, hence the use of
this convention: either the target understands it and it works as
expected or it does not and it is harmless. I don't think there is any
other purpose.
-- 
Habit is habit, and not to be flung out of the window by any man, but coaxed
down-stairs a step at a time.
		-- Mark Twain, "Pudd'nhead Wilson's Calendar