How to convert DATE to UNIX TIMESTAMP in shell scr

Question

On Linux you can convert a date like "2010-10-02" to a unix timestamp in shell script by

date -d "2010-10-02" "+%s"

Since Mac OS does not have the equivalent -d for date. How do you go about converting a date to a unix timestamp in a shell script.

Answer 1

Alternatively you can install GNU date like so:

1. install Homebrew: https://brew.sh/
2. brew install coreutils
3. add to your bash_profile: alias date="/usr/local/bin/gdate"
4. date +%s 1547838127

The Mac is "different" because OSX is based on BSD. BSD utilities tend to be conservatively updated, while GNU tools have more enhancements.

Really, if you spend most of your time in Linux, but have a Mac desktop, you probably want to make the Mac work like Linux. Also see: Docker. There's no sense in trying to remember two different sets of options.

Answer 2

man date on OSX has this example

date -j -f "%a %b %d %T %Z %Y" "`date`" "+%s"

Which I think does what you want.

You can use this for a specific date

date -j -f "%a %b %d %T %Z %Y" "Tue Sep 28 19:35:15 EDT 2010" "+%s"

Or use whatever format you want.

Answer 3

I used the following on Mac OSX.

currDate=`date +%Y%m%d`
epochDate=$(date -j -f "%Y%m%d" "${currDate}" "+%s")

Answer 4

date +%s

This works fine for me on OS X Lion.

Answer 5

date -j -f "%Y-%m-%d" "2010-10-02" "+%s"