如何在Bash脚本中根据samplesheet的Group列执行对应函数

我有一个包含三个函数的Bash脚本，需要根据samplesheet.txt中Group列的信息决定执行哪个函数：Group=Both时执行process_both，Group=DNA时执行process_dna，Group=RNA时执行process_rna。当前脚本的执行逻辑未按Group列匹配，请问如何修改脚本实现该功能？

附samplesheet.txt内容 #

DNA             RNA            purity    Group
sample_DNA_1    sample_RNA_1    0.8      Both
sample_DNA_2    sample_RNA_2    0.5      Both
NA              sample_RNA_4    0.3      RNA
sample_DNA_3    NA              0.1      DNA

现有代码 #

process_both() {
    local dna=$1
    local rna=$2
    local purity=$3
        singularity exec \
        sing.sif \
        ...
        ...
        dna_id {dna} \
        rna_id {rna} \
        purity {purity} \
        ...

        }
    
process_dna() {
    local dna=$1
    local rna=$2
    local purity=$3
        singularity exec \
        sing.sif \
        ...
        ...
        dna_id {dna} \
        purity {purity} \
        ...

        }

process_rna() {
    local dna=$1
    local rna=$2
    local purity=$3
        singularity exec \
        sing.sif \
        ...
        ...
        rna_id {rna} \
        purity {purity} \
        ...

        }


# Run the functions

tail +2 samplesheet.txt | while read dna rna purity
do
    process_both "$dna" "$rna" "$purity"
done

tail +2 samplesheet.txt | while read dna rna purity
do
    process_rna "$dna" "$rna" "$purity"
done    

tail +2 samplesheet.txt | while read dna rna purity
do
    process_dna "$dna" "$rna" "$purity"
done

解决方案 #

原脚本的问题在于：三次重复读取samplesheet，且完全没有依据Group列做判断，导致所有函数会被全量执行。修改思路是单次循环读取所有字段，根据Group值分支调用对应函数，修改后的完整代码如下：

process_both() {
    local dna=$1
    local rna=$2
    local purity=$3
        singularity exec \
        sing.sif \
        ...
        ...
        dna_id ${dna} \
        rna_id ${rna} \
        purity ${purity} \
        ...
}
    
process_dna() {
    local dna=$1
    local rna=$2
    local purity=$3
        singularity exec \
        sing.sif \
        ...
        ...
        dna_id ${dna} \
        purity ${purity} \
        ...
}

process_rna() {
    local dna=$1
    local rna=$2
    local purity=$3
        singularity exec \
        sing.sif \
        ...
        ...
        rna_id ${rna} \
        purity ${purity} \
        ...
}


# Run the functions
tail +2 samplesheet.txt | while read dna rna purity group
do
    case "${group}" in
        "Both")
            process_both "$dna" "$rna" "$purity"
            ;;
        "DNA")
            process_dna "$dna" "$rna" "$purity"
            ;;
        "RNA")
            process_rna "$dna" "$rna" "$purity"
            ;;
        *)
            echo "Unknown Group value: ${group} for DNA=${dna}, RNA=${rna}" >&2
            ;;
    esac
done

关键修改点说明 #

1. 读取Group字段：在read命令中添加group变量，确保读取到每行的Group列值
2. 单次循环处理：只读取一次samplesheet，避免重复IO操作
3. 分支判断逻辑：用case语句根据Group值精准调用对应函数，同时增加默认分支处理未知Group值的情况（可选，用于错误排查）
4. 修正变量引用：原函数内的{dna}需改为${dna}才能正确解析Bash变量（原代码存在语法错误）

内容的提问来源于stack exchange，提问作者user2300940