Linux shell script date formatting

Unix/Linux date FAQ: How do I create a formatted date in Linux? (Or, “How do I create a formatted date I can use in a Linux shell script?”)

I just ran into a case where I needed to create a formatted date in a Linux shell script, where the desired date format looks like this:


To create this formatted date string, I use the Linux date command, adding the + symbol to specify that I want to use the date formatting option, like this:

thedate=`date +"%Y-%m-%d"`

The Linux date command shown in this line of code creates the date string in the format I want, and then I save the formatted date output to a Linux shell script variable named thedate.

This just shows one possible way to format a date in a Linux shell script. Of course you can use '-', '.', and many other characters as date field separators, or use no characters at all.

Note that after you have a formatted date for your shell script, you can create a filename variable like this:


In that example I’m creating a filename that’s unique every day, which I can later refer to as $filename in my script.

More Linux date formatting information

For more information on other Linux date formatting options (there are many more date formatting options), take a look at the man page for the date command on your Linux system, like this:

man date

When I run that command on a CentOS Linux system, it shows these date-formatting operators:

%%     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., 21)

%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

%g     last two digits of year of ISO week number (see %G)

%G     year of ISO week number (see %V); normally useful only with %V

%h     same as %b

%H     hour (00..23)

%I     hour (01..12)

%j     day of year (001..366)

%k     hour ( 0..23)

%l     hour ( 1..12)

%m     month (01..12)

%M     minute (00..59)

%n     a newline

%N     nanoseconds (000000000..999999999)

%p     locale’s equivalent of either AM or PM; blank if not known

%P     like %p, but lower case

%r     locale’s 12-hour clock time (e.g., 11:11:04 PM)

%R     24-hour hour and minute; same as %H:%M

%s     seconds since 1970-01-01 00:00:00 UTC

%S     second (00..60)

%t     a tab

%T     time; same as %H:%M:%S

%u     day of week (1..7); 1 is Monday

%U     week number of year, with Sunday as first day of week (00..53)

%V     ISO week number, with Monday as first day of week (01..53)

%w     day of week (0..6); 0 is Sunday

%W     week number of year, with Monday as first day of week (00..53)

%x     locale’s date representation (e.g., 12/31/99)

%X     locale’s time representation (e.g., 23:13:48)

%y     last two digits of year (00..99)

%Y     year

%z     +hhmm numeric timezone (e.g., -0400)

%:z    +hh:mm numeric timezone (e.g., -04:00)

%::z   +hh:mm:ss numeric time zone (e.g., -04:00:00)

%:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)

%Z     alphabetic time zone abbreviation (e.g., EDT)

As an example, here’s a time formatting example from 11:32am this morning:

$ t=`date +"%H.%M.%S"`

$ echo $t

Because Unix and Linux systems are very consistent in this area, you should be able to write a date formatting command on one Unix or Linux system, and use that same command on another Unix system.