bash 循环遍历 CSV 文件并在读取时创建新的 csv 文件？
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Loop through CSV file and create new csv file with while read?
提问by Buttle Butkus
I have
我有
while read $field1 $field2 $field3 $field4
do
$trimmed=$field2 | sed 's/ *$//g'
echo "$trimmed","$field3" >> new.csv
done < "$FEEDS"/"$DLFILE"
Now the problem is with readI can't make it split fields csv style, can I? See the input csv format below.
现在的问题是read我无法将其拆分为 csv 样式，可以吗？请参阅下面的输入 csv 格式。
I need to get columns 3 and 4 out, stripping the padding from col 2, and I don't need the quotes.
我需要取出第 3 列和第 4 列，从第 2 列中去除填充，并且不需要引号。
Csv format with col numbers: 12 24(")25(,)26(")/27(Field2values) 42(")/43(,)/44(Field3 decimal values) "Field1_constant_value","Field2values ",Field3,Field4
带有列号的 Csv 格式：12 24(")25(,)26(")/27(Field2values) 42(")/43(,)/44(Field3 十进制值) "Field1_constant_value","Field2values ",Field3,场 4
Field1 is constant and irrelevant. Data is quoted, goes from 2-23 inside the quotes. Field2 fixed with from cols 27-41 inside quotes, with the data at the left and padded by spaces on the right. Field3 is a decimal number with 1,2, or 3 digits before the decimal and 2 after, no padding. Starts at col 74. Field4 is a date and I don't much care about it right now.
Field1 是常数且无关紧要。数据被引用，从引号内的 2-23 开始。Field2 用引号内的 cols 27-41 固定，数据在左边，右边用空格填充。Field3 是一个十进制数，小数点前有 1,2 或 3 位数字，小数点后有 2 位，没有填充。从第 74 栏开始。 Field4 是一个日期，我现在不太关心它。
回答by Rubens
Yes, you can use read; all you've got to do is reset the environment variable IFS-- Internal Field Separator --, so that it won't split lines by its current value (default to whitespace), but by your own delimiter.
是的，您可以使用 read；你所要做的就是重置环境变量IFS——内部字段分隔符——，这样它就不会按当前值（默认为空格）拆分行，而是按你自己的分隔符。
Considering an input file "a.csv", with the given contents:
考虑具有给定内容的输入文件“a.csv”：
1,2,3,4
2,3,4,5
6,3,2,1
1,2,3,4
2,3,4,5
6,3,2,1
You can do this:
你可以这样做：
IFS=','
while read f1 f2 f3 f4; do
echo "fields[$f1 $f2 $f3 $f4]"
done < a.csv
And the output is:
输出是：
fields[1 2 3 4]
fields[2 3 4 5]
fields[6 3 2 1]
字段[1 2 3 4]
字段[2 3 4 5]
字段[6 3 2 1]
回答by TheRuss
A couple of good starting points for you are here: http://backreference.org/2010/04/17/csv-parsing-with-awk/
几个很好的起点在这里：http: //backreference.org/2010/04/17/csv-parsing-with-awk/
