Linux date Command: Day of Week

To find the day of week (e.g. Friday) on a particular date using the Linux version of the `date` utility, execute:

$ date -d 'Jan 03 2004' "+%a"
Sat

The -dflag tells the utility to display the information only, instead of setting the date, etc.

The "+%a" options are`date`'s FORMAT options, which are listed in the manpages.
So, for example, we can also have the full name of the weekday output by changing the "+%a" to "+%A".

$ date -d 'Jan 03 2004' "+%A"
Saturday

DATE(1)                             User Commands

NAME
       date - print or set the system date and time

SYNOPSIS
       date [OPTION]... [+FORMAT]
...
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FORMAT controls the output.  Interpreted sequences are:

       %%     a literal %

       %a     locale's abbreviated weekday name (e.g., Sun)

       %A     locale's full weekday name (e.g., Sunday)

       %b     locale's abbreviated month name (e.g., Jan)

       %B     locale's full month name (e.g., January)

       %c     locale's date and time (e.g., Thu Mar  3 23:05:25 2005)

       %C     century; like %Y, except omit last two digits (e.g., 20)

       %d     day of month (e.g., 01)

       %D     date; same as %m/%d/%y

       %e     day of month, space padded; same as %_d

       %F     full date; same as %Y-%m-%d
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