Readers:
I'm writing in regard to ksh scripts I wrote to the ksh88 standards which have
run for years on many HP-UX/PA-RISC and Solaris/Sparc platforms, and, even a
few Linux/x86_64) platforms ... until this week. Upon running the scripts on
CentOS 6.4/x86-x64 with Korn shell "Version AJM 93u+ 2012-08-01", non-null
values being returned to a calling function are sometimes retrieved by the
caller as null values.
Specifically, in the edited excerpts following, the variable ToDo always
contains a value in fSendReqToSvr prior to fSendReqToSvr returning. When
fSendReqToSvr returns in fGetFileStatusFromSvr, Todo is often assigned a null
value. The context of this script is as a child invoked by another ksh script
run from cron. I've included the code reassigning stdout and stderr on the
chance this is somehow significant.
What don't I understand?
OS: CentOS-6.4 (x86-64) Development Installation Korn Shell: Version: AJM 93u+
2012-08-01 Package: Ksh.x86_64 20120801-10.el6
...
function fLogOpen
{
...
exec 3>$1 #C# Assigned Fd 3 to a log file
#C# stdout and stderr are redirected to log file as insurance that
#C# no "errant" output from script (1700 lines) "escapes" from script.
#C# stdout and stderr restored in fLogClose.
exec 4>&1
exec 1>&3
exec 5>&2
exec 2>&3
...
}
...
#C# Invokes curl on behalf of caller and evaluates the outcome, returning
#C# a string specifying what the caller should do.
function fSendReqToSvr
{
typeset Err=0 ... \
ToDo=CONTINUE ... \
CL="$2" ...
Typeset -I iSecsLeft=$1 iSleepSecs=3
...
curl $CL > $CurlOutFFS 2>&1 &
gCurlPId=$!
while (( iSecsLeft > 0 )) ; do
...
#C# Sleep N secs, check status of curl with "kill -0 $gCurlPId"
#C# and if curl exited, get return code from "wait $gCurlPId".
...
(( iSecsLeft = iSecsLeft - iSleepSecs ))
done
...
#C# Evaluate curl return code and contents of CurlOutFFS file to
#C# determine what to set ToDo to. ToDo is - without exception -
#C# assigned a string like "CONTINUE", "NEXT_FILE", etc.
...
#C#
print -n -- "$ToDo" #C# ToDo confirmed to always have a value here
return $Err
}
...
function fGetFileStatusFromSvr
{
typeset Err=0 ... \
ToDo=CONTINUE ... \
...
...
ToDo=$( fSendReqToSvr "$iSessMaxSecs" "$CurlCmdLine" )
Err=$?
#C# ToDo contains null here
...
return $Err
}
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