9 Nov
2017
9 Nov
'17
3:04 p.m.
Hi Will,
Why does the first of these incantations not present
text, but the
second does (word is a file)? Neither errors out.
$ <word | sed 20q
$ <word sed 20q
That's still the case with modern-day sh(1).
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#ta…
explains that a simple command doesn't need to result in a command name
to execute. In your first pipeline, there's nothing to copy the data
from the first subshell's stdin redirected from ./word to the subshell's
stdout that's pipes into sed's stdin. Adding a command to do the copy
works.
<word cat | sed 20q
--
Cheers, Ralph.
https://plus.google.com/+RalphCorderoy