如何在shell中使用多列进行循环？

Question

我有一个包含三列（ID 号、x、y）的文件

ifile.txt
1      32.2    21.4
4      33.2    43.5
5      21.3    45.6
12     22.3    32.5
32     21.5    56.3
43     33.4    23.4
44     23.3    22.3
55     22.5    32.4

我想在第 2 列和第 3 列上做一个循环，这样读起来就像

for x=32.2 and y=21.4; do execute a fortran program
for x=33.2 and y=43.5; do execute the same program
and so on

尽管我的以下脚本正在运行，但我需要以有效的方式使用它。

s1=1   #serial number
s2=$(wc -l < ifile.txt)   #total number to be loop
while [ $s1 -le $s2 ]
do
x=$(awk 'NR=='$s1' {print $2}' ifile.txt)
y=$(awk 'NR=='$s1' {print $3}' ifile.txt)
cat << EOF > myprog.f
...
take value of x and y
...
EOF
ifort myprog.f
./a.out
(( s1++ ))
done

请注意：myprog.f 是在 cat 程序中编写的。例如，

cat << EOF > myprog.f
....
....
take value of x and y
....
....
EOF

Answer 1

在 bash 中读取文件的简单方法是

while read -r _ x y; do
    echo "x is $x, y is $y"
    # your Fortran code execution
done < ifile.txt
x is 32.2, y is 21.4
x is 33.2, y is 43.5
x is 21.3, y is 45.6
x is 22.3, y is 32.5
x is 21.5, y is 56.3
x is 33.4, y is 23.4
x is 23.3, y is 22.3
x is 22.5, y is 32.4