CODEWITHSUNDEEP
macosshelldate
axiaoxin
axiaoxin

Reputation: 318

how to use shell convert from 01/Mar/2011 to 2011-03-01 on OS X

I want to know how to use shell convert from 01/Mar/2011 to 2011-03-01 on OS X?

in my bash:

bash-3.2$ date -d "03 Mar 2011" +%F
usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

Thank @ghoti, on OS X should use like:

date -j -f '%d %b %Y' "02 JUN 2011" '+%F'
Failed conversion of ``02 JUN 2011'' using format ``%d %b %Y''
date: illegal time format
usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

but, my system show me > date +%b 7, %b is a number, not an abbreviated month name.

Thanks.

Upvotes: 1

Views: 1051

Answers (2)

Babu
Babu

Reputation: 23

The idea is to convert date STRING to epoch time, then output it as the format you desire.

I tested it on Cygwin and CentOS.

convert date STRING to epoch time

use command 'date -d STRING +%s', STRING can be 01 Mar 2011 or 01-Mar-2011 or 01/03/2011

date -d '01 Mar 2011' +%s
1298908800

output epoch time to date format

use command 'date -d @EPOCH_TIME '+%Y-%m-%d'

date -d @1298908800 '+%Y-%m-%d'
2011-03-01

Because your date STRING 01/Mar/2011 is not a valid format for date -d, so you have to use 'sed' to convert it.

echo "01/Mar/2011"|sed -e 's/\// /g'
01 Mar 2011

So your solution can be

old_date="01/Mar/2011"

date_string=`echo "$old_date"|sed -e 's/\// /g'`

echo $date_string
01 Mar 2011

epoch_time=`date -d "$date_string" +%s`

echo $epoch_time
1298908800

date -d @$epoch_time '+%Y-%m-%d'
2011-03-01

Upvotes: 0

ghoti
ghoti

Reputation: 46856

Using BSD date, you can convert one format to another by using the -f option.

For example, putting your input into a variable so you can see how to re-use this date command:

$ d="27 JUN 2011"
$ date -j -f '%d %b %Y' "$d" '+%F'
2011-06-27

You can man date to see how everything works, but the basics are this;

  • -j tells the command just to process input and not try to set your system clock.
  • -f this that uses this as an input format to interpret that.
  • +yadda uses the specified output format to print the interpreted date.

For details on the input format, on OS X or most BSDs, you can man strftime.

Upvotes: 1

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