Finding Day of the week from date

Shell Programming and Scripting
1

I have a problem of Finding Day of the week from date, but i need to do it within awk On SOLARIS

Input:20101007(YYYYMMDD)
Output:Thursday

kindly provide suggestions.

Thanks in advance

2

nawk, not awk

Go here: AWK Language Programming - A Library of awk Functions
Get the code for the mktime() function, which returns epoch seconds from a date. Note: read the article, you need to get several functions, not just one.
The number 0 .. 6 of the day of the week is

dow= (epochseconds / 86400 ) % 7

If you need day names, then create an array and access each element by dow,
day_name[dow]

3

You can give this a try:

#!/bin/sh

# Day of the week (YYYYMMDD)

d="20101007"

day=${d#??????}
temp=${d#????}
month=${temp%??}
year=${d%????}

DOW=$(cal $month $year | awk '
BEGIN{split("Sun Mon Tue Wed Thu Fri Sat",dow);dow[0]=dow[7]}
NR==3{t=7-NF+d;print dow[t%7];exit}' d=$day)

echo $DOW

Use nawk or /usr/xpg4/bin/awk on Solaris.

4

If it is current date then you can use :

date +"%A"

5

Check out the gnu date command from their corutils ,

Examples of date - GNU Coreutils

You can do this:
$ date -d 20101007 "+%A"
Thursday

You can get the output for whatever date you put in after the -d

6

FreeBSD

# date -j -f "%Y%m%d" "20101007" "+%A"
Thursday

or just

# date -d 20101007 "+%A"
Thursday
7

Thanks all for you replies:

On my solaris machine date -d doesn't work.
Niether does date -j -f...:((

Franklin52: I have to do this process (dow) for every record in a file, besides other fuctions that are to be performed on other fields of data.

I have written a piece of code as:

awk 'BEGIN{
	FS="|";
	while(getline < "DAY_MAPPING_NEW.CFG")
	{
	DAY_NEW[$2]=$1; DAY_NEW[$3]=$1; DAY_NEW[$4]=$1; DAY_NEW[$5]=$1; DAY_NEW[$6]=$1; DAY_NEW[$7]=$1;
	}
}
{
	dd=substr("'${DATE}'",7,2);
	mm=substr("'${DATE}'",5,2);
	yyyy=substr("'${DATE}'",1,4);
	system("cal "mm" "yyyy" | tail -7|tr \" \" \";\"|tr \"\\n\" \";\" >out.txt");
	while(getline < "out.txt")
	{OPFILE=$0;}
	if (int(dd) <= 9) {	dd=substr("'${DATE}'",8,1);	}
	newdd=";"dd";"
	daynum=index(OPFILE,newdd);
	print "New Date is:"dd"|"mm"|"yyyy"|"DAY_NEW[daynum];
	system("rm out.txt");


	OTHER FUNCTIONALITIES
		.
		.
		.
		.
		..
		..
		.
		.
		..
}' INPUTFILE.txt

But i want to get output of system commant in some variable rather than writting o/p in a file "out.txt' and removing it everytime.

8

Replace these lines:

system("cal ..." >out.txt");
while(getline < "out.txt")
{OPFILE=$0;}

with:

while("cal ..."| getline OPFILE) {..}
9

Franklin:
I tried following possiblities

while(("cal "month" "year" | tail -7|tr \" \" \";\"|tr \"\\n\" \";\" | getline OPFILE"))
{
print "Here...."OPFILE
}

while(("cal "month" "year" | tail -7|tr \" \" \";\"|tr \"\\n\" \";\"" | getline OPFILE))
{
print "Here...."OPFILE
}

while(system("cal "month" "year" | tail -7|tr \" \" \";\"|tr \"\\n\" \";\"" | getline OPFILE))
{
print "Here...."OPFILE
}

while(system("cal "month" "year" | tail -7|tr \" \" \";\"|tr \"\\n\" \";\" | getline OPFILE"))
{
print "Here...."OPFILE
}

But none worked...