# Avoiding date using printf

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.

# Get the current date

$ printf '%(%F)T\n'

# Set variable to current time

$ printf -v now '%(%T)T'
$ echo "$now"

# 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.