I used https://crontab.guru/ as an inspiration for cron values.
The format is <minute> <hour> <day of month> <month> <day of week>
* any value
, value list separator
- range of values
/ step values
0-59 allowed values
* any value
, value list separator
- range of values
/ step values
0-24 allowed values
* any value
, value list separator
- range of values
/ step values
0-31 allowed values
* any value
, value list separator
- range of values
/ step values
0-12 allowed values
Jan-Dec alternative single values
* any value
, value list separator
- range of values
/ step values
0-12 allowed values
Sun-Sat alternative single values
You can run tests with sbt test command
You can build executable artifact with sbt assembly command.
It will build a jar file named cron-parser.jar which will be located in /target/scala-2.12/ directory
You can either run the artifact with java -jar target/scala-2.12/cron-parser.jar "*/15 0 1,15 * 1-5 /usr/bin/find" command
or by running com.dl.CronParser from your IDE with a single program argument which should contain a cron expression with a command.
The reason to have it as a single program argument with space-separated values (instead of providing 6 arguments) is related to the * character:
when it is specified as one of a program's argument it will replace this argument with names of the files in current directory.
for */15 0 1,15 * 1-5 /usr/bin/find:
minute 0 15 30 45
hour 0
day of month 1 15
month 1 2 3 4 5 6 7 8 9 10 11 12
day of week 1 2 3 4 5
command /usr/bin/find
for */8 1,3,14,23 * Mar-Sep/2 Thu-Sat /usr/bin/find:
minute 0 8 16 24 32 40 48 56
hour 1 3 14 23
day of month 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
month Mar May Jul Sep
day of week Thu Fri Sat
command /usr/bin/find