Re: [Help-bash] Odd behaviour using $(...)

[Peter West]

Thanks for that.

A follow-up question arises from your advice about ‘typeset -i’.  If I change 
my shell execution mode to
  #! /bin/bash -—posix
or
  #! /bin/sh —-posix
I get no complaints about ‘typeset -i’.  Does this mean that I can’t run a bash 
shell in a manner that will conform to a minimal shell, or that a posix shell 
is a different beast to a basic ’sh’?  Or does it mean that the ‘-i’ is 
ignored, and that that is not noticed because it makes no difference in this 
instance?

Peter West
"Why do you seek the living among the dead? He is not here, but has risen."

> On 22 Apr 2015, at 6:09 pm, Pierre Gaston <address@hidden> wrote:
> 
> On Wed, Apr 22, 2015 at 9:11 AM, Peter West <address@hidden> wrote:
> 
>> The following script, called as 'tiktst', executes as expected when
>> invoked directly from the shell.
>> --------------------------------------------------------------
>> #! /bin/sh
>> TIKA_APP=${TIKA_APP:="$JARS/tika-app.jar"}
>> 
>> typeset -i port=45000
>> 
>> msg () { echo Using port $port; }
>> 
>> pid () { echo Server PID $!; }
>> 
>> case $(basename $0) in
>>    tiktst)
>>        msg; java -jar "$TIKA_APP" --detect --server $port & pid ;;
>>    *)
>>        echo "Server not executed. Program name not known." >&2 ;;
>> esac
>> 
>> echo Exited from case statement
>> exit 0
>> -------------------------------------------------------------
>> 
>> Here's the output:
>> $ tiktst
>> Using port 45000
>> Server PID 11899
>> Exited from case statement
>> 
>> 
>> However, if I try to capture the output like so:
>> $ res=$(tiktst)
>> 
>> the shell hangs. At this point, the shell in which I have executed this
>> statement has no children, and the java process is a child of init.  I can
>> type commands, which echo to the terminal, but do not execute, until I kill
>> the java process, whereupon they will execute.
>> 
>> If I 'set -x' I will see all of the commands in debug output, including
>> the final 'exit 0' and the java command.  If I put 'sleep 2' after the java
>> invocation, I see the java command in the dubug output before the 'exit 0';
>> otherwise the java command is echoed to debug after the exit 0.
>> 
>> What's going on?
>> 
>> OS X 10.10.3 bash 3.2.57(1)
>> 
>> Peter West
>> "Why do you seek the living among the dead? He is not here, but has risen."
>> 
>> 
>> 
> $( ) waits for stdout to be closed, since your server continues to run in
> the background stdout stays open
> add >/dev/null after you java command an you should be ok....even better
> close all the fds:
> java >/dev/null 2>&1 </dev/null
> 
> 
> (as an aside typeset -i is not needed and implies that your shell is
> bash/ksh while you are using /bin/sh in your shebang, so you should
> probably remove it)