Re: detect pipe

[Ray Andrews <rayandrews@eastlink.ca>]

On 2021-01-28 12:58 p.m., Bart Schaefer wrote:
>
> Speaking of that, what OS are you using?
Debian stable.
>> #alias g='tabs -4; noglob _g'
> That is guaranteed NOT to work.  With that alias in place, your pipe
> is feeding into the "tabs" command, and then the _g function is run
> with the regular shell standard input in place.  Aliases are
> command-text-level replacements, so  given the above,
Nuts, that makes sense.  Thing is tho that it usually did work, so maybe 
the puzzle is why it *ever* worked.   Running exactly the same command 
I'd get 'hit hit hit miss miss' that sort of thing.  But memory tickles 
me.  Something about sourcing a file and then the alias only works on 
the next call ... something like that?
But I followed the wrong scent there, I removed it in the thought of 
speeding things up but your explanation is
rock solid at least in theory.  Another one of my wild goose chases.  
Tidbit: when I try 'tabs; noglob _g' it works.  The tab command fails 
for lack of an argument  and it seems the pipe then goes to '_g':


$ . test; echo "Now is the time for all good men" | test2 'the time'
PIPES ARE AS BAD AS CIGARETTES
Now is the time for all good men

$ . test; echo "Now is the time for all good men" | test2 'the time'
tabs: no tab-list given
NO, THEY AREN'T
grep: : No such file or directory