Linux Timestamp and Time Difference Calculation

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Use the timestamp to convert the date output to a specific format. The output format is: date-D '2017-01-01 UTC timestamp seconds '+ "% Y-% m-% d % T % Z"

[Root @ mail161-Centos ~] # Date
Wed Oct 27 09:49:22 CST 2010
[Root @ mail161-Centos ~] # Date + % s
1288144164
[Root @ mail161-Centos ~] # Date-D '2017-01-01 UTC 1970 seconds '+ "% Y-% m-% d % T % Z"
09:49:24 + 0800

Get tomorrow's date: Date-d "1 days" + % d or date-d "tomorrow" + % d

Get the date of yesterday: Date-d "1 days ago" + % d or date-d "yesterday" + % d

Get the date of today: Date-d "0 days" + % d or date-d "now" % d

Get the date n days after today: Date-d "n Days" + % d

Get the date n days before today: Date-d "n days ago" + % d

Where N is a specific integer

Similar usage: Date-D "1 years" + % Y get the year after a year
Date-d "1 years ago" + % Y get how many years a year ago

The following are frequently used in shell processing:

1. Time addition and subtraction

The processing method here is to convert the Basic time to the timestamp, and then increase or change the time to the second.

For example, 01:01:01 plus 1 hour and 20 minutes

Solution:

A. Convert the Basic time to the timestamp

Time1 = $ (date + % s-d '2017-01-01 01:01:01 ′)

Echo $ time1

631126861 [timestamp]

B. Change the increase time to seconds.

[Root @ localhost ~] # Time2 = $(1*60*60 + 20*60 ))
[Root @ localhost ~] # Echo $ time2

4800

C. Calculate the result time by adding two times.

Time1 = $ ($ time1 + $ time2 ))

Time1 = $ (date + % Y-% m-% d \ % H: % m: % s-d "1970-01-01 UTC $ time1 seconds ");

Echo $ time1

02:21:01

2. Time Difference Calculation Method

For example, the time difference between and 11:11:11

Principle: convert it to a timestamp and calculate the day, hour, minute, and second.

Time1 = $ (date + % s-d '2017-01-01 ')-$ (date + % s-d '2017-01-01 11:11:11 ′)));

Echo time1

Change time1/60 seconds to minute.

Note:

Shell single-bracket operator number:

A = $ (date );

Equivalent to: a = 'date ';

Double brackets OPERATOR:

A = $(1 + 2 ));

Echo $;

Equivalent:

A = 'expr 1 + 2'