Bash uses `

• Bash Script Convert Julian Date To A Calendar Date Today
• Convert Julian Date To Calendar Date In Unix
• Bash Script Convert Julian Date To A Calendar Date
• Bash Script Convert Julian Date To A Calendar Date Calendar

date

There are some options for doing this job in the R package date. See for example on page 4, the function date.mmddyy, which says. Given a vector of Julian dates, this returns them in the form “10/11/89”, “28/7/54”, etc. New Date.getTime/86400000 + 2440587.5 will get the unix time stamp, convert it to days and add the JD of 1970-01-01, which is the epoch of the unix time stamp. This is what astronomers call julian date. It is well defined. Since neither Unix time stamp nor JD take leap seconds into account that does not reduce the accuracy. What is Julian date? Julian date calendar was introduced by Julius Caesar. The length of Julian date is 5, in which first 2 digits represt the year and last 3 digits represent the day of the year. For example:-1 st January 2008, Julian date 08001. Where “08” being the year and “001” being the date; To convert the Julian date format to a. I used the script to convert julian dates to calendar dates. I have a problem with the months thought. It works fine for month 1 and 2 but for March and on I get negative values. Instead of 3 for March I get -9. Could you please help?

` command to display or change the current date and time value of the system. Date and time value can be printed in different formats by using this command. This command can also be used for calculating date and time value related tasks. `date` command without any option just prints the current system’s date and time value. This command has many formatting options to format the output. The uses of these options are shown in this tutorial by using various examples.

Syntax:

Different format codes or characters can be used with the date options to generate the formatted output. Some common options and format types are mentioned below.

Options:

-d or –date=String	It displays the time set by the String value.
-s, –set=String	It sets the time set by the String value.
-f or –file=DateFile	It is used to process multiple dates.
-I or –iso-8601[=Timespec]	It is used to create an ISO 8601 compliant date/time string output.
-r or –reference=File	It is used to display the last modification time of a file.
-u, –utc, –universal	It is used to display or set Coordinated Universal Time.
–help	It is used for getting the help of this command.
–version	It is used to get version information.

Some Format codes:

%a	Print weekday names in short form (e.g., Sun)
%A	Print full weekday names (e.g., Sunday)
%b	Print month name in short form (e.g., Jan)
%B	Print full month name (e.g., January)
%c	Print date and time (e.g., Mon Mar 11 23:05:25 2019)
%C	Print century; like %Y, except omit last two digits (e.g., 25)
%d	Print day of the month (e.g, 01)
%Y	Print 4 digits year (e.g. 2019)
%y	Print 2 digits year (e.g. 19)
%D	Print date; same as %m/%d/%y
%e	Print day of the month, same as, %d
%F	Print full date; same as, %Y-%m-%d

Example-1: Display date in the particular format

By default `date` displays the current date and time value. Each part of date and time values can be printed separately by using different data options. The following command will print the date value only.

Output:

Here, ‘%d’ is used for printing day value, ‘%B’ is used for printing full month name and ‘%Y’ is used for printing full year value.

Example-2: Change the current date and time

The current date and time value can be changed by using -s option. You must have root privilege to change the system’s date and time. The following command will change the current date to ‘03/17/2019’ and time to ‘03:30:00‘.

Output:

Example-3: Find the particular date and time using days

Sometimes we need to find out the future or previous date and time. Any date can find out by using `date` command and defining days, month and year values in –date option. The following commands will calculate the date and time after 15 days and before 15 days.

Output:

Example-4: Find the particular date and time using times

Like the previous example, future or previous times can be calculated by using `date` command. The following commands will calculate the future time after ‘5 hours 20 minutes’ of current times and before 2 hours and 20 minutes of current times.

Output:

Example-5: Convert current date and time to UNIX epoch time

According to UNIX epoch time, the time value is calculated in seconds from the date, 1^st January 1971. This time value can be used to calculate the time difference. `date` command can be used to convert any date value to UNIX epoch time. The following command will convert the current system date and time to UNIX epoch time.

Output:

Example-6: Convert UNIX epoch time to date and time

Using `date` command anyone can convert any UNIX epoch time to date and time value. The following command converts ‘1552298500′ epoch value to its corresponding date and time value.

Output:

Example-7: Find out the weekday based on date

`date` command can be used to find out the weekday name, month name or year value from any date value. The following command will find the weekday name of 1^st January 2019 and the output is ‘Tuesday’.

Output:

Example-8: Using date command in a bash script

A bash file named timediff.sh is created with the following code. In this script, two date values are taken from command line arguments which are stored on $1 and $2. $START variable stored the UNIX epoch time value of $1 and $END variable stored the UNIX epoch time value of $2. The difference between these two values is calculated and stored to $diff variable in seconds. Next, the seconds are converted to days and printed.

timediff.sh

The script is executed with two date values as command line arguments. Here, 2019-01-01 and 2020-01-01 dates are used and the difference between these two dates is 365 days.

Conclusion

You can use `date` command for various purposes in the bash script. Some uses of date values are explained in this tutorial with the above examples. You can also use this command to separate the parts of time value by using different options and formats. Hope, this tutorial will help the readers to understand the use of `date` command and apply them properly.

I often get asked how to convert a datetime into Julian Date format in T-SQL. People have differing opinions about what Julian means, but the one I got asked about most recently meant YYDDD, as often used by mainframe systems (I think this is Julian Date, as opposed to Julian Day which is the number of days since 4713BC). SQL Server doesn’t have a TO_JULIAN function, but we can make one easily enough.

So we’re wanting to express a date as YYDDD, where YY is the two-digit form of the year, and DDD is the number of days since Dec 31st of the previous year (ie, the DDDth day of the year).

Using the DATEPART function can get each part. YY for the year, and DY for the day of the year. I’m going to use @date as a variable here, of type datetime. Using the date type in SQL 2008 would work just the same.

SELECT DATEPART(yy, @date), DATEPART(dy, @date)

However, to make sure that we have the year in two-digits only, we should convert this to a string and get the rightmost two characters.

SELECT RIGHT(CAST(DATEPART(yy, @date) AS char(4)),2)

We also need to pad the DDD with zeroes – which I’ll do by putting three zeroes in front of the number and getting the three rightmost characters.

SELECT RIGHT(‘000’ + CAST(DATEPART(dy, @date) AS varchar(3)),3)

Concatenating the YY and the DDD, we now have a TO_JULIAN function.

SELECT RIGHT(CAST(YEAR(@date) AS CHAR(4)),2) + RIGHT(‘000’ + CAST(DATEPART(dy, @date) AS varchar(3)),3)

Converting back again isn’t too hard – it’s just a matter of pulling the numbers out of the 5-character string. I’m going to assume we have a char(5) called @julian.

We need to split the string up first.

SELECT LEFT(@julian,2), RIGHT(@julian,3)

Bash Script Convert Julian Date To A Calendar Date Today

The first bit becomes the year easily enough

SELECT CONVERT(datetime, LEFT(@julian,2) + ‘0101’, 112)

The second half can be cast to a number, and then added back (subtracting one to get the maths right) using DATEADD.

Convert Julian Date To Calendar Date In Unix

SELECT DATEADD(day, CAST(RIGHT(@julian,3) AS int) – 1, CONVERT(datetime, LEFT(@julian,2) + ‘0101’, 112))

Bash Script Convert Julian Date To A Calendar Date

So now we have a FROM_JULIAN function:

SELECT DATEADD(day, CAST(RIGHT(@julian,3) AS int) – 1, CONVERT(datetime, LEFT(@julian,2) + ‘0101’, 112))

Bash Script Convert Julian Date To A Calendar Date Calendar

Easy stuff really, just a matter of thinking about what we mean by a particular format.