Chunk_submit: submit bash commands by user defined number of chunks
In ZhenWei10/RbashGEO: GEO raw data processing in bash.

1	Chunk_submit(Commands, Chunk = 6, Name)

`Commands`	the vector of commands we want to submit (do not need to include nohup portion).
`Chunk`	number of parallel processes.
`Name`	the names of the script and output files.

file_names <- grep(".fq$", list.files("/home/zhen/PAR-CLIP/Trim"), value = T)
commands <- paste0("fastq_to_fasta -i ",file_names," -o ", gsub("fq","fa",file_names),"{\}n",
                  "fastx_collapser -i ",gsub("fq","fa",file_names)," -o ", gsub("trimmed.fq","collapsed.fa",file_names))
Chunk_submit(commands,6,"collapse")