bash date - ghdrako/doc_snipets GitHub Wiki

  • Bash 4.2 added printf %(datefmt)T
  • There are two special arguments,
    • -1, which means “now,” and
    • -2, which means “the time the shell was invoked.”
### Set a $today variable using -v
$ printf -v today '%(%F)T' '-1'
$ echo $today
2021-08-13

### Trivial logging (these are the same)
$ printf '%(%Y-%m-%d %H:%M:%S %z)T: %s\n' '-1' 'Your log message here'
$ printf '%(%F %T %z)T: %s\n' '-1' 'Your log message here'
2021-08-13 12:48:33 -0400: Your log message here
### When was 1628873101?
$ printf '%(%F %T)T = %s\n' '1628873101' 'Epoch 1628873101 to human readable'
2021-08-13 12:45:01 = Epoch 1628873101 to human readable

### show the name of the month from two months ago
$ date -d '2 months ago' '+%B'

$ date +%s 
1629582882
$ date -d @1629582882 '+%m/%d/%Y:%H:%M:%S'
08/21/2021:21:54:43

date --date="next week Fridey"
date --date="now"
date --date="tomorrow"
date --date="yesterday"
date --date="last week"
date --date="next week"
date --date="last month"
date --date="2015-09-12"
date --date="08/01/2015"
date -r start.sh  # -r  find the last modified time of the file
vi file-$(date "+%Y-%m-%d_%I:%M:%S").txt

dd abbreviates to date --date="<given_date>".

date "<some_format>" # prints the date in the specified format
  • %Y is the current year
  • %m is the current month
  • %d is today's date
  • %I is hours
  • %M is minutes
  • %S is seconds
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