for循環回顯順序命令行？

Question

如何在linux中使用for循環來生成以下幾行？

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 

我已經試過：

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

卻原來是三個相同的線。

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 

感謝

Answer 1

$aD是一個有效的變量名。您必須用括號將變量名稱分隔，即${a}。