Avoiding date using printf

Introduction#

In Bash 4.2, a shell built-in time conversion for printf was introduced: the format specification %(datefmt)T makes printf output the date-time string corresponding to the format string datefmt as understood by strftime.

Syntax#

• printf ’%(dateFmt)T’ # dateFmt can be any format string that strftime recognizes
• printf ’%(dateFmt)T’ -1 # -1 represents the current time (default for no argument)
• printf ’%(dateFmt)T’ -2 # -2 represents the time the shell was invoked

Remarks#

Using printf -v foo '%(...)T' is identical to foo=$(date +'...') and saves a fork for the call to the external program date.

Get the current date

$ printf '%(%F)T\n'
2016-08-17

Set variable to current time

$ printf -v now '%(%T)T'
$ echo "$now"
12:42:47