How do I get the difference between two dates in bash?

1. Provide valid time string in A and B.
2. Use date -d to handle time strings.
3. Use date %s to convert time strings to seconds since 1970 (unix epoche)
4. Use bash parameter expansion to subtract seconds.
5. divide by seconds per day (86400=60*60*24) to get difference as days.
6. ! DST is not taken into account ! See this answer at unix.

How do you find the difference between two dates in shell?

There’s a solution that almost works: use the %s date format of GNU date, which prints the number of seconds since 1970-01-01 00:00. These can be subtracted to find the time difference between two dates. Because of daylight savings time, there are only 23 hours between those times.

What does date do in bash?

Bash uses `date` command to display or change the current date and time value of the system. Date and time value can be printed in different formats by using this command. This command can also be used for calculating date and time value related tasks.

How do I date in bash?

To get the date in bash shell and add a date, you can use the GNU date command as date -d ‘Feb 12 +1 day’ +%F which will output 2020-02-13 .

What is let in bash?

let is a bash and ksh keyword which allows for variable creation with simple arithmetic evaluation. If you try to assign a string there like let a=”hello world” you’ll get a syntax error. Works in bash and ksh93 . $(…) is command substitution, where you literally take the output of a command and assign to a variable.

Is let a bash command?

Bash let builtin command

• On Unix-like operating systems, let is a builtin command of the Bash shell that evaluates arithmetic expressions.
• Using let is similar to enclosing an arithmetic expression in double parentheses, for instance: (( expr ))

How do I increment a bash counter?

Using + and – Operators The most simple way to increment/decrement a variable is by using the + and – operators. This method allows you increment/decrement the variable by any value you want.

How to calculate the difference between times in Bash?

You can use date (assuming the GNU implementation) with command substitution, and to get the difference between the times use arithmetic expansion: The result is in seconds. datediff is from the dateutuils package. Note in opposite to the date command, dateutils ignores locale settings by default using GMT.

What are the dates in the bash script?

The script is executed with two date values as command line arguments. Here, 2019-01-0 1 and 2020-01-01 dates are used and the difference between these two dates is 365 days. You can use `date` command for various purposes in the bash script. Some uses of date values are explained in this tutorial with the above examples.

Where are the date values stored in Bash?

A bash file named timediff.sh is created with the following code. In this script, two date values are taken from command line arguments which are stored on $1 and $2. $START variable stored the UNIX epoch time value of $1 and $END variable stored the UNIX epoch time value of $2.

What is the result of Bash dateutils calculation?

The result is in seconds. Note in opposite to the date command, dateutils ignores locale settings by default using GMT. This can make one hour difference regarding the adjustment to daylight savings time. The above supposes that the user is interested in only the difference in hour and minutes and ignores day differences.