for循环回显顺序命令行？

Question

如何在linux中使用for循环来生成以下代码行？

zcat ~/tools/sample66621D.fastq | bowtie2 -a - | samtools ->sample66621D.BAM
zcat ~/tools/sample66622D.fastq | bowtie2 -a - | samtools ->sample66622D.BAM
zcat ~/tools/sample66623D.fastq | bowtie2 -a - | samtools ->sample66623D.BAM

我试过了：

for ((a=21;a<=23;a++))
  echo "zcat ~/tools/sample666$aD.fastq | bowtie2 -a - | samtools ->sample666$aD.BAM"
done

但它变成了三行相同的代码。

zcat ~/tools/sample666.fastq | bowtie2 -a - | samtools ->sample666.BAM
zcat ~/tools/sample666.fastq | bowtie2 -a - | samtools ->sample666.BAM
zcat ~/tools/sample666.fastq | bowtie2 -a - | samtools ->sample666.BAM

谢谢

Answer 1

$aD是有效的变量名。必须用括号分隔变量名，例如${a}。