I have a large number of files. It is paired end sequencing. my files are of type _1.fastq.gz and _2.fastq.gz. in the fastp command I must enter the 2 files corresponding to the same samples in _1 and _2 in the form fastp -i file_a_1.fastq.gz -I file_a_2.fastq.gz. how could I do this for all my files without having to manually write the command with each file? when there is only one variable i do a loop for i in $ (ls Fastq_dir / *. fastq.gz) do ... But with 2 variables ?