Re: Using << and an output pipe together in shell (bash)

Il Fri, 1 Nov 2024 09:01:15 -0000 (UTC), Kenny McCormack ha scritto:

I think I actually prefer to stick with; > >(cmd ...)

Note that

cat << EOF | grep . ; echo end

and also

(cat | grep .) << EOF ; echo end

produce the same output:
---------------------------------------------------------
lem@biggy:~$ cat << EOF | grep . ; echo end
start
EOF
start
end
lem@biggy:~$
---------------------------------------------------------
lem@biggy:~$ (cat | grep .) << EOF ; echo end

start
EOF

start
end
lem@biggy:~$
---------------------------------------------------------

Instead with "cat << EOF > >(grep .) ; echo end" the output is
unpredictable. You can very well get, as usual:
---------------------------------------------------------
lem@biggy:~$ cat << EOF > >(grep .) ; echo end
start
EOF
start
end
lem@biggy:~$
---------------------------------------------------------
OR maybe:
---------------------------------------------------------
lem@biggy:~$ cat << EOF > >(grep .) ; echo end
start
EOF
end
start
lem@biggy:~$
---------------------------------------------------------
OR even, most of the time:
---------------------------------------------------------
lem@biggy:~$ cat << EOF > >(grep .) ; echo end
start
EOF
end
lem@biggy:~$ start [you press ENTER here and get back an empty prompt]

lem@biggy:~$
---------------------------------------------------------

So sometimes it's better to be careful. :)
--
Bye, Lem