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date

Calculate Date to Epoch Time

Here’s a script to convert date to epoch time on Mac OS.

#!/bin/bash
if [[ -z $1 ]]; then
  echo "Format: date2epoch.sh 2022/01/01-04:58:06"
else
  echo "$1"; date -j -f date -j -f "%Y/%m/%d-%T" "$1" +"%s"
fi

Result

$ ./date2epoch.sh 2022/08/31-22:00:00
2022/08/31-22:00:00
1661997600

Set Linux Time Zone

Here’s another way of setting Linux time zone.

Check server time.

# check server time
date

Change to local time.

# set to local time
rm /etc/localtime
ln -s /usr/share/zoneinfo/America/Los_Angeles /etc/localtime

Check server time again.

# check server time again
date

Calculate Epoch Time to Date

Here’s how to calculate epoch time using the Linux date command.

# Linux
date --date @1561266781
date -d @1561266781
# MacOS
date -r 1561266781

Output is : Sun Jun 23 05:13:01 UTC 2019

Show current epoch time.

date +%s

Output: 1561642643

Add date to filenames

Here’s how to add date stamps to filenames. Uses epoch time.

tar cpzf mybackup-`date +%s`.gz /home/user

A month ago

How to get last month’s value. Useful with Bash scripts.

LASTMONTH = $(date +%Y%m -d '1 month ago')
echo $LASTMONTH
# Output is ...
201902