使用sqoop将mysql表导入hive报错Output directory hdfs://hadoop:9820/user/hadoop/${target_dir} already exists

场景：
使用sqoop将mysql表导入hive报错如下：
ERROR tool.ImportTool: Import failed: org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://hadoop:9820/user/hadoop/${target_dir} already exists
        at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:164)
?       at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:280)
        at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:146)
        at org.apache.hadoop.mapreduce.Job$11.run(Job.java:1570)
        at org.apache.hadoop.mapreduce.Job$11.run(Job.java:1567)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:422)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1729)
        at org.apache.hadoop.mapreduce.Job.submit(Job.java:1567)
        at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1588)
        at org.apache.sqoop.mapreduce.ImportJobBase.doSubmitJob(ImportJobBase.java:200)
        at org.apache.sqoop.mapreduce.ImportJobBase.runJob(ImportJobBase.java:173)
        at org.apache.sqoop.mapreduce.ImportJobBase.runImport(ImportJobBase.java:270)
        at org.apache.sqoop.manager.SqlManager.importQuery(SqlManager.java:748)
        at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:522)
        at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:628)
        at org.apache.sqoop.Sqoop.run(Sqoop.java:147)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
        at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:183)
        at org.apache.sqoop.Sqoop.runTool(Sqoop.java:234)
        at org.apache.sqoop.Sqoop.runTool(Sqoop.java:243)
        at org.apache.sqoop.Sqoop.main(Sqoop.java:252)

解决：
查看脚本${target_dir}参数应该为/user/hive/warehouse/import/htest/${hive_table}，但这里为什么没有识别到呢，
只是传进来了这个参数的名称而已，经检查发现，在--target-dir   \这个参数里的值为'${target_dir}'，其应该为
"${target_dir}"，更改后再执行就好