Shell time operation and calculation method _linux Shell

In recent time, when dealing with shell scripts, encountered time processing problems. The addition and subtraction of time, as well as the calculation of timing.

I. Time Plus and minus

The way to do this is to turn the base time into a timestamp, and then you need to add or change time to seconds.

For example: 1990-01-01 01:01:01 plus 1 hours 20 minutes

Processing method:

A. Converting the base time to time stamp

time1=$ (Date +%s-d ' 1990-01-01 01:01:01 ')

echo $time 1

631126861 "timestamp"

B. Increase the time into seconds

[Root@localhost ~]# time2=$ ((1*60*60+20*60))
[Root@localhost ~]# echo $time 2

4800

C. Two time added to calculate the result time

time1=$ (($time 1+ $time 2))

time1=$ (date +%y-%m-%d\%h:%m:%s-d "1970-01-01 UTC $time 1 Seconds");

echo $time 1

1990-01-01 02:21:01

Second, the calculation method of time difference

such as: 2010-01-01 and 2009-01-01 11:11:11 time lag

Principle: Also turn into a timestamp, and then calculate the day, time, minutes, seconds

Time1=$ (($ (Date +%s-d ' 2010-01-01 ')-$ (Date +%s-d ' 2009-01-01 11:11:11 '));

Echo time1

Will time1/60 seconds, will become divided.

Supplementary Note:

Shell single bracket operator symbol:

Copy Code code as follows:

a=$ (date);

Equivalent to: a= ' Date ';

Double bracket Operator:

Copy Code code as follows:

a=$ ((1+2));

echo $a;

Equivalent to:

Copy Code code as follows:

A= ' expr 1 + 2 '