Re: Use of pipe in $(< filename | program) returns null

[pk]

Chet Ramey wrote:

> root@saturn.syslang.net wrote:
> 
>> Description:
>> use of $(< filename | program) does not work. It either should or it
>> should be properly documented. The problem also happens on bash4.
>> 
>> Repeat-By:
>> 
>> qq=$(< /etc/passwd | grep sys)
>> echo $qq
>> # result is null
>> 
>> Fix:
>> Either fix the docs to tell people that a pipe is not allowed or fix the
>> code to allow it.
> 
> That construct is very limited.  As the bash man page says:
> 
> The command substitution $(cat file) can be replaced by the equivalent
> but faster $(< file).
> 
> That seems pretty clear.

Yeah, and then based on that he probably thought that

$(cat file | grep sys)

could be replaced by

$(< file | grep sys)

which is not the case.