BPE syntax error

Well,I am new to OpenNMT and I am trying to use BPE for my corpus.
Whenever i try to run this code
tools/learn_bpe.lua -size 30000 -save_bpe codes -tok_mode aggressive -tok_segment_numbers -tok_case_feature < dev.en

I end up getting this error
tools/learn_bpe.lua: line 1 :syntax error near unexpected token 'torch'' tools/learn_bpe.lua: line 1:require(‘torch’)’

can anyone help me with this?