bash 如何将变量传递给 awk 命令行
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how to pass in a variable to awk commandline
提问by user3799576
I'm having some trouble passing bash script variables into awk command-line.
我在将 bash 脚本变量传递到 awk 命令行时遇到了一些麻烦。
Here is pseudocode:
这是伪代码：
for FILE in $INPUT_DIR/*.txt; do
filename=`echo $FILE | sed -n 's/^.*\(chr[0-9A-Z]*\).*.vcf$//p'`
OUTPUT_FILE=$OUTPUT_DIR/$filename.snps.txt
egrep -v "^#" $FILE | awk '{print ,,}' > $OUTPUT_FILE
done
The final line where I awk the columns, I would like it to be flexible or user input. For example, the user could want columns 6,7,and 8 as well, or column 133 and 138, or column 245 through 248. So how do I custom this so I can have that 'print $2 .... $5' be a user input thing? For example the user would run this script like : bash script.sh input_dir output_dir [user inputs whatever string of columns], and then I would get those columns in the output. I tried passing it in, but I guess I'm not getting the syntax right.
我对列进行 awk 的最后一行，我希望它是灵活的或用户输入。例如，用户可能还需要第 6,7 和 8 列，或第 133 和 138 列，或第 245 至 248 列。那么我如何自定义它，以便我可以让“打印 $2 .... $5”成为用户输入的东西？例如，用户会像这样运行这个脚本：bash script.sh input_dir output_dir [用户输入任何列的字符串]，然后我会在输出中得到这些列。我尝试传入它，但我想我的语法不正确。
采纳答案by Michal Krzyz
The following test works for me:
以下测试对我有用：
A="$3" ; ls -l | awk "{ print $A }"
回答by aherrero
With awk, you should declare the variable before use it. This is better than the escape method (awk '{print $'$var'}'):
使用 awk，您应该在使用之前声明变量。这比转义方法更好（awk '{print $'$var'}'）：
awk -v var1="$col1" -v var2="$col2" 'BEGIN {print var1,var2 }'
Where $col1 and $col2 would be the input variables. Maybe you can try an input variable as string with "$2,$4,$5" and print this variable to get the values (I am not sure if this works)
其中 $col1 和 $col2 将是输入变量。也许您可以尝试将输入变量作为带有 "$2,$4,$5" 的字符串并打印此变量以获取值（我不确定这是否有效）
