When you are creating a job, variable wildcards are supported in the job parameters for both time and date.

Variable wildcard format

The format of the variable wildcards supported by E-MapReduce is either ${dateexpr-1d} or ${dateexpr-1h}. For example, assuming the current date and time is 2016/04/27 12:08:01:

  • If ${yyyyMMdd HH:mm:ss-1d} is displayed, the parameter wildcard is replaced with 20160426 12:08:01 when executed, which is the current date minus one day, and time accurate to the second.
  • If ${yyyyMMdd-1d} is displayed, the parameter wildcard is replaced with 20160426 when executed, which is the current date minus one day.
  • If ${yyyyMMdd} is displayed, the parameter wildcard is replaced with 20160427, which is the current date.

dateexpr represents the standard format of expressing time. Time is therefore formatted according to this expression and is followed by the amount of time that you want to add or deduct, which can be written as N. For example, ${yyyyMMdd-5d}, ${yyyyMMdd+5d}, ${yyyyMMdd+5h}, or ${yyyyMMdd-5h}.

Note E-MapReduce currently supports the addition and deduction of hours and days only.

Example

When executed, the Parameter in the following figure will be replaced with: 
jar ossref://emr/jar/hadoop/hadoop_wc.jar com.aliyun.emr.WordCount oss://emr/output/pt=20160426