An hquery pipe to hquery is processed interactively and not via stdin

[mdgabriel]

Consider

% for x in A B C D; do hquery "create $x <x:double>[i=0:0];"; done

that creates the arrays A, B, C and D. The following pipes to hquery works as expected

% echo "remove(A); remove(B); remove(C); remove(D);" | hquery

and

% hquery<<EOF
> remove(A);
> remove(B);
> remove(C);
> remove(D);
> EOF

and

% hquery -ocsv "project(list('arrays'),name);" | sed -r -n "/('A'|'B'|'C'|'D')./s/^.'([^'])'.$/remove(\1);/p" > remove.qy
% cat remove.qy | hquery

However, the follow pipe also works but outputs interactive output and prompts

% hquery -ocsv "project(list('arrays'),name);" | sed -r -n "/('A'|'B'|'C'|'D')./s/^.'([^'])'.$/remove(\1);/p" | hquery
SciDB version 19.11.0
{No} name,port,instance_id,online_since,instance_path
{0} 'localhost',1239,0,'2020-03-13 20:45:46','/home/scidb/scidbtrunk/stage/DB-mydb/0/0'
{1} 'localhost',1240,3,'2020-03-13 20:45:46','/home/scidb/scidbtrunk/stage/DB-mydb/0/1'
{2} 'dev2',1242,4294967297,'2020-03-13 20:45:46','/home/scidb/scidbtrunk/stage/DB-mydb/1/3'
{3} 'dev2',1241,4294967298,'2020-03-13 20:45:46','/home/scidb/scidbtrunk/stage/DB-mydb/1/2'
True/dcsv/0? True/dcsv/0? True/dcsv/0? True/dcsv/0? True/dcsv/0? %

[mdgabriel]

Surprisingly, the follow works

% hquery -ocsv "project(list('arrays'),name);" | sed -r -n "/('A'|'B'|'C'|'D')./s/^.'([^'])'.$/remove(\1);/p" | (sleep 1; hquery)

[mdgabriel]

Upon review, hReady is only a suggestion and not a guarantee. One needs to introduce the option --wait-on-stdin (-W) to guarantee that hquery waits for stdin in a pipe.

[mdgabriel]

For the record, here is a cleaner example without sed
to remove arrays A, B, C and D

% hquery -otsv "project(apply,filter(list('arrays'),regex(name,'A|B|C|D')),
remove,'remove('+name+');'),remove);" | hquery -W

[mdgabriel]

This issue is resolved with commit b568c3e.