Days Between

A command line utility for working with date ranges.

Examples

# Calculate the number of days between dates
# Use YYYYMMDD or YYYY-MM-DD
$ <path>/days_between 20180101 2018-01-01 # 0

# A more practical example
$ <path>/days_between 19700101 20170901 # 17410

# Showing the short offset option
$ <path>/days_between 20180209 -o=3 # 20180212

# Offset can be negative; it can also come first
$ <path>/days_between -o=-3 2018-02-09 # 2018-02-06

# The list option prints start to end
$ <path>/days_between 2018-02-09 -o=3 -l
# 2018-02-09
# 2018-02-10
# 2018-02-11
# 2018-02-12

# All options can come before the start date
$ <path>/days_between -o=-3 -l 2018-02-09
# 2018-02-09
# 2018-02-08
# 2018-02-07
# 2018-02-06

$ <path>/days_between 2017-12-29 2018-01-01 -l -f=%v
# 29-Dec-2017
# 30-Dec-2017
# 31-Dec-2017
#  1-Jan-2018

$ <path>/days_between days_between 2018-01-01 2017-12-29 -l
# 2018-01-01
# 2017-12-31
# 2017-12-30
# 2017-12-29

# The today (-t, --today) option can be used in place of the start date
$ <path>/days_between --today -o=3 # 2018-02-24 when run on 2018-02-21

# today is always the start date, even if listed after a date
$ <path>/days_between 2018-01-01 --today # -51 when run on 2018-02-21

API

• ./days_between [<start_date> or --today] [<end_date> OR --offset=integer] [options]

Date format: YYYYMMDD or YYYY-MM-DD.

The output format matches the start date format for offset calculations and can be overridden and customized using the format option. If the today option is used, the default output format is YYYY-MM-DD.

Options

• -h, --help Print help info
• -l, --list Prints all dates in the calculated range (e.g. for xargs input)
• -o, --offset Calculate the date this many days offset the start date. Positive or negative integer.
• -t, --today Use today's date as the start date for the calculation.
• -f, --format Specify the output date format (defaults to matching start date format). See chrono::format::strftime for options.

Setup

Download a release binary

See the GitHub releases.

Build from source with cargo

1. git clone
2. cd days_between
3. cargo build --release
4. The executable will be days_between/target/release/days_between

Tips

If you commonly need to know the days since a particular date, make an alias.

Bash - put this in your .bashrc/.bash_profile/etc. to easily calculate the days since Jan. 1, 1970.

alias dse='<path>/days_between 19700101'

Fish - run in terminal

$ abbr --add dse '<path>/days_between 19700101'