linux awk命令实现输出每一列数据的最大值、最小值

root@PC1:/home/test# ls
test.txt
root@PC1:/home/test# cat test.txt
3 4 2 2
1 9 5 7
5 7 8 4
2 3 4 6

root@PC1:/home/test# ls
test.txt
root@PC1:/home/test# cat test.txt
3 4 2 2
1 9 5 7
5 7 8 4
2 3 4 6
root@PC1:/home/test# for i in `head -n 1 test.txt | awk '{print NF}' | xargs seq`; do temp=$(head -n 1 test.txt | awk -v a=$i '{print $a}'); awk -v b=$i -v c=$temp 'BEGIN{max  = c} {if($b > max) {max = $b}} END {print max}' test.txt >> max.txt; done
root@PC1:/home/test# ls
max.txt  test.txt
root@PC1:/home/test# cat max.txt
5
9
8
7
root@PC1:/home/test# paste -d " " -s max.txt  ## 转换为行的形式
5 9 8 7

root@PC1:/home/test# ls
test.txt
root@PC1:/home/test# cat test.txt
3 4 2 2
1 9 5 7
5 7 8 4
2 3 4 6
root@PC1:/home/test# for i in `head -n 1 test.txt | awk '{print NF}' | xargs seq`; do temp=$(head -n 1 test.txt | awk -v a=$i '{print $a}'); awk -v b=$i -v c=$temp 'BEGIN{min  = c} {if($b < min) {min = $b}} END {print min}' test.txt >> min.txt; done
root@PC1:/home/test# ls
min.txt  test.txt
root@PC1:/home/test# cat min.txt
1
3
2
2
root@PC1:/home/test# paste -d " " -s min.txt  ## 转换为列的形式
1 3 2 2

dir()
dat <- read.table("test.txt", header = F)
dat
apply(dat, 2, max)
apply(dat, 2, min)

> dir()
[1] "test.txt"
> dat <- read.table("test.txt", header = F)  ## 读取测试数据
> dat
  V1 V2 V3 V4
1  3  4  2  2
2  1  9  5  7
3  5  7  8  4
4  2  3  4  6
> apply(dat, 2, max)   ## 求每一列的最大值
V1 V2 V3 V4 
 5  9  8  7 
> apply(dat, 2, min)   ## 求每一列的最小值
V1 V2 V3 V4 
 1  3  2  2