Post a Comment On: j4neiros

A solution for: http://www.linuxjournal.com/content/work-shell-what-day-date-past

No AWK involved.


#!/bin/bash


# We need 3 arguments:
# DOW, Month and Day


if [ $# -ne 3 ]
then
        echo "Usage: $(basename $0) weekday month day"
        echo "(example: $(basename $0) 4 3 2)"
        exit 1
fi


# We use the date command for checking


date -d "$2/$3" &> /dev/null


if [ "$?" == "1" ]
then
        echo "$(basename $0) Error: Invalid date!"
        exit 1
fi


# Month as number
M=$(date -d "$2/$3" +%m)


# The day of the month
D=$(date -d "$2/$3" +%e | sed 's/ //')


WD=$1


# The day of year is gonna help us decide which is
# the first year to test: current year or the previous one
DOY=$(date -d "$2/$3" +%j)
CDOY=$(date +%j)


Y=$(date +%Y)


if [ ${DOY} -gt ${CDOY} ]
then
        Y=$(expr ${Y} - 1)
fi


echo $M $D $WD $DOY $CDOY $Y


F=''
until [ -n "${F}" ]
do
        echo -n $Y $M =


        # The calendar for the month and year
        # Extract the line with the day of the month
        # Add numbers to the lines, the number will be
        # used to identify the Day of the Week
        # Extract the line of the particular day
        # gotta be careful cause 6 1 is the sixth line day 1
        # and 1 6 is the first line day 6, so we search by the second number
        # Convert the multiple spaces in front of the numbers into one space
        # so the cut command always return the second field
        # Extract the first number only, that's the DOW


        CWD=$(cal ${M} ${Y} \

                | grep "\b${D}\b" \
                | sed 's/[ ][ ][ ]\|[ ][ ]\|[ ]/|/g; s/^|//; s/|/\n/g' \
                | cat -n \
                | grep "\b${D}\b$" \
                | tr -s [:space:] ' ' \
                | cut -d ' ' -f 2)


        if [ ${WD} -eq ${CWD} ]
        then
                F=Found
        fi


        echo $CWD


        Y=$(expr ${Y} - 1)
done


##END##

The output of searching the first date in the past when March 1 was Wednesday:
janeiros@harlie:~/tmp$ ./t.sh 4 3 1 03 1 4 061 087 2012 2012 03 =5 2011 03 =3 2010 03 =2 2009 03 =1 2008 03 =7 2007 03 =5 2006 03 =4
janeiros@harlie:~/tmp$ cal 3 2006      March 2006 Su Mo Tu We Th Fr Sa           1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31