fix the bugs of shell scripts

egs/tibetan/asr/run.sh

@@ -50,7 +50,7 @@ specific_prefix=st
 specific_dir=${root_dir}/data/mustc/st
 specific_dir=${root_dir}/data/mustc/st
 asr_vocab_prefix=spm_unigram10000_st_share
 asr_vocab_prefix=spm_unigram10000_st_share
 
 
-if [[ -z ${subset} ]]; then
+if [[ -n ${subset} ]]; then
     dataset=${dataset}/${subset}
     dataset=${dataset}/${subset}
 fi
 fi
 org_data_dir=${root_dir}/data/${dataset}
 org_data_dir=${root_dir}/data/${dataset}