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Pass the value from pipe

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# 1  
Old 04-05-2015
Pass the value from pipe
am trying to pass the date calculated to variable so that i can use the same for my further reporting and tracking of the changes as per the variable value.

System = SunOS
Release = 5.9
KernelID = Generic_122300-61

Code:
date '+%m %d %Y' |
{
read MONTH DAY YEAR
DAY=`expr "$DAY" - 1`
case "$DAY" in
        0)
                MONTH=`expr "$MONTH" - 1`
                        case "$MONTH" in
                                0)
                                        MONTH=12
                                        YEAR=`expr "$YEAR" -1`
                                ;;
                        esac
                DAY=`cal $MONTH $YEAR | grep . | fmt -1 | tail -1`
esac
vardt=$?
if [ $vardt -ne 0 ];then
        echo "ERROR DURING SPOOLING PREVIOUS DAY DATE."
        exit 1
fi
YESTERDAY=${MONTH}/${DAY}/${YEAR};export YESTERDAY
} | YDAY=${YESTERDAY};export YDAY
echo $YDAY

OUTPUT in debug mode
Code:
+ date +%m %d %Y
+ read MONTH DAY YEAR
YDAY=
+ export YDAY
+ echo
+ expr 05 - 1
DAY=4
vardt=0
+ [ 0 -ne 0 ]
YESTERDAY=04/4/2015
+ export YESTERDAY

Request to help me please and thanks in advance.
# 2  
Old 04-05-2015
Just as date printed three values that you used read to import into the second stage of your pipeline, you need to print the results you want to export from the second stage of your pipeline and read the results in the third stage of your pipeline. The third stage of your pipeline is not in a subshell environment of the execution environment of the second stage of your pipeline; so variables exported in the second stage of your pipeline are not visible in the third stage of your pipeline.

Code:
date '+%m %d %Y' |
{
read MONTH DAY YEAR
DAY=`expr "$DAY" - 1`
case "$DAY" in
        0)
                MONTH=`expr "$MONTH" - 1`
                        case "$MONTH" in
                                0)
                                        MONTH=12
                                        YEAR=`expr "$YEAR" -1`
                                ;;
                        esac
                DAY=`cal $MONTH $YEAR | grep . | fmt -1 | tail -1`
esac
vardt=$?
if [ $vardt -ne 0 ];then
        echo "ERROR DURING SPOOLING PREVIOUS DAY DATE."
        exit 1
fi
echo "${MONTH}/${DAY}/${YEAR}"
} |
{
read YDAY
export YDAY
echo $YDAY
}

Last edited by Don Cragun; 04-06-2015 at 05:34 PM.. Reason: Put export and echo at end of script in a subshell.
This User Gave Thanks to Don Cragun For This Post:
pradeep84in
# 3  
Old 04-06-2015
That works, but only in ksh, which i didn't see the requestor mention. In other shells, the third stage is executed in a subshell, and the value read will not be available in the calling shell. You could use read with bash's process substitution here, or a variable assignment with command substitution.
# 4  
Old 04-06-2015
Quote:
Originally Posted by RudiC
That works, but only in ksh, which i didn't see the requestor mention. In other shells, the third stage is executed in a subshell, and the value read will not be available in the calling shell. You could use read with bash's process substitution here, or a variable assignment with command substitution.
Ouch. Yes. I intended to include an additional set of braces or parentheses making the last three lines all be a subshell as the 3rd stage of the pipeline. I will update post #2 momentarily.
# 5  
Old 04-07-2015
If you want the variable in the main shell (instead of a subshell)
then define a function:
Code:
yday() { 
    date '+%m %d %Y' | { 
        read MONTH DAY YEAR;
        DAY=`expr "$DAY" - 1`;
        case "$DAY" in 
            0)
                MONTH=`expr "$MONTH" - 1`;
                case "$MONTH" in 
                    0)
                        MONTH=12;
                        YEAR=`expr "$YEAR" -1`
                    ;;
                esac;
                DAY=`cal $MONTH $YEAR | grep . | fmt -1 | tail -1`
            ;;
        esac;
        vardt=$?;
        if [ $vardt -ne 0 ]; then
            echo "ERROR DURING SPOOLING PREVIOUS DAY DATE.";
            exit 1;
        fi;
        echo "${MONTH}/${DAY}/${YEAR}"
    }
}
# main shell
YDAY=`yday`
echo $YDAY

This User Gave Thanks to MadeInGermany For This Post:
pradeep84in
# 6  
Old 04-08-2015
That did the trick Smilie

Thanks so much for the help and explanations guys, that is GREATLY appreciated! Smilie
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