pg_dumpall not working when start it with QProcess - postgresql

Question

I want to copy my data and tables from one postgres installation to the other, source version listens on port 5432 destination server on port 5433. User myUser is superuser on both versions.
Postgres "pg_dumpall" does not working when start it with QProcess
but the command works in windows cmd, this here:
pg_dumpall -p 5432 -U myUser | psql -U myUser -d myDbName -p 5433
But not from Qt code using QProcess:
QProcess *startProgram = new QProcess();
startProgram->start("pg_dumpall -p 5432 -U myUser | psql -U myUser -d myDbName -p 5433");
startProgram->waitForFinished()
return true
startProgram->exitCode();
returns 1
startProgram->exitStatus();
return 0
Anyway my data and tables are not copied to destination.
Creating db with QProcess works by using:
startProgram->start("createdb -p 5433 -U myUser myDbName");

Answer 1

Yeah its a bit annoying, I was trying to do the same thing with ls | grep <pattern> type commands - which spawn off multiple processes...
I came up with this for linux:
if (QProcess::startDetached("xfce4-terminal -x bash -c \"ls -l | grep main > out\""))
{
qDebug("ok\n");
}
else
{
qDebug("failed\n");
}
So basically if I break that down:
QProcess runs xfce4-terminal (or which ever term you want) with the execute parameter -x:
xfce4-terminal -x <command to execute>
This then executes bash with the command parameter -c (in escaped quotes):
bash -c \"bash command\"
Finally the bash command:
ls -l | grep main > out
So for your application you could substitute the final command (part 3) with:
pg_dumpall -p 5432 -U myUser | psql -U myUser -d myDbName -p 5433
I am assuming you are using linux? (there is a similar possibility for windows which uses cmd instead of terminal. Also you can probably just replace xfce4-terminal for gnome-terminal which is perhaps more common, but might need to check the -x is the same.... IIRC it is.
There is probably a nicer way to do this.... but I wanted to harness the power of bash, so this seemed the logical way to do it.
Further: I think you can just do this:
QProcess::startDetached("bash -c \"ls -l | grep main > out\"")
And get rid of the terminal part, (works for simple stuff like ls), but I am not sure if all the paths and what-not are setup... worth a go as it is a little neater and removes your reliance on any particular terminal...

Answer 2

Thank you! Yes, the pipe was the problem.
In windows this works for me:
QProcess *startProgram = new QProcess();
startProgram->start("cmd /c \"pg_dumpall -p 5432 -U myUser | psql -U myUser -d myDbName -p 5433\"");