linux 中实现按列的索引循环

1、

root@DESKTOP-1N42TVH:/home/test# ls
a.txt
root@DESKTOP-1N42TVH:/home/test# cat a.txt
i A Em F
d q ddd M
d e N ffff
i A Em F
d q ddd M
d e N ffff
root@DESKTOP-1N42TVH:/home/test# for i in $(seq `head -n 1 a.txt | awk '{print NF}'`); do echo $i; done
1
2
3
4

 

2、

root@DESKTOP-1N42TVH:/home/test# ls
a.txt
root@DESKTOP-1N42TVH:/home/test# cat a.txt
i A Em F
d q ddd M
d e N ffff
i A Em F
d q ddd M
d e N ffff
root@DESKTOP-1N42TVH:/home/test# for i in `head -n 1 a.txt | awk '{print NF}' | xargs seq`; do echo $i; done
1
2
3
4