Can an alias ever have a dynamic element?

Can an alias ever have a dynamic element?

[zzapper]

Hi

I have an alias which creates a tar with a date component in its name that 
date is however evaluated when the shell is created which could have been a 
few days ago. The easy solution is to create a script but is they any 
alternative?

Re: Can an alias ever have a dynamic element?

[Phil Pennock]

On 2013-12-17 at 15:20 +0000, zzapper wrote:
> I have an alias which creates a tar with a date component in its name that 
> date is however evaluated when the shell is created which could have been a 
> few days ago. The easy solution is to create a script but is they any 
> alternative?

Use a function.

There are a very few use-cases for aliases, which mostly boil down to
"need to mess with how zsh parses the command-line"; otherwise, you
should use functions.  Use functions unless and until you know you need
an alias.

"alias -g" for in-place mutations, or plain aliases which tinker with
state in some other way, but otherwise, use functions.

    function tar_with_initial_timestamp {
      zmodload -i zsh/datetime || return 1
      local invoked_s invoked_rendered
      invoked_s=$(( EPOCHSECONDS - SECONDS ))
      TZ="" strftime -s invoked_rendered "%Y%m%d_%H%M%SZ" $invoked_s
      tar cvf "capture_$invoked_rendered.tar" "$@"
    }

    tar_with_initial_timestamp dir1 dir2 metadata.json

-Phil

Re: Can an alias ever have a dynamic element?

[Bart Schaefer]

On Dec 17,  3:20pm, zzapper wrote:
}
} I have an alias which creates a tar with a date component in its name
} that date is however evaluated when the shell is created which could
} have been a few days ago. The easy solution is to create a script but
} is they any alternative?

This usually means you've created the alias with something like:

    alias thingy="foo $(date)"

when what you need are single rather than double quotes:

    alias thingy='foo $(date)'

Always best if you actually show us an example rather than attempt to
describe it in prose.

Re: Can an alias ever have a dynamic element?

[zzapper]

Bart Schaefer > }
> } I have an alias which creates a tar with a date component in its name
> } that date is however evaluated when the shell is created which could
> } have been a few days ago. The easy solution is to create a script but
> } is they any alternative?
> 
> This usually means you've created the alias with something like:
> 
>     alias thingy="foo $(date)"
> 
> when what you need are single rather than double quotes:
> 
>     alias thingy='foo $(date)'
> 
> 

LOL I foolishly never realised that single and double quotes behaved 
differently for aliases!!

alias maketar='dw && zargs ./**/*.{php,inc,js} -- tar rvf /tmp/serviceplan
$(date "+%d-%m-%Y").tar

Thanks Bart

https://twitter.com/dailyzshtip