linux - for循环回显顺序命令行？

Question

如何在linux中使用for循环生成下面几行？

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:

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

却变成了三行一模一样的行。

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 是一个有效的变量名。您必须用方括号分隔变量名称，即 ${a}。