awk的printf插入多个变量的正确语法是什么? [英] what is the correct syntax for awk's printf to insert multiple variables?

问题描述

我复制了一些使用printf的代码来输出字​​符串在文件中出现的频率.

I copied some code that was using printf to output how often strings appeared in files.

awk ' BEGIN {  print "The number of times a appears in the file:" ; }
/a/ {  a_counter+=1  ;  }
END {  printf "%s\n",  a_counter ; }
'  $file

将模式修改为变量后，我想将模式包括在计数旁边的printf命令中:

After modifying the pattern to a variable, I wanted to include the pattern into the printf command, next to the count:

awk -v a="$GENE1" ' BEGIN {  print "The number of times", a, " appears in the file are:" ; }
$0 ~ a {  a_counter+=1  ;  }
END {  printf "%s\n", a, a_counter ; }
'  $file

现在，它仅显示a的值，而不显示a_counter的值.我读到printf更为复杂，可能不应该像使用print那样添加多个用，"分隔的字符串.但是我找不到正确的方法吗?我当然可以坚持使用print，但是我想了解在printf的情况下我做错了什么?

Now it only prints the value of a, but not of a_counter. I read that printf is more complex and I'm probably not supposed to add multiple strings separated with "," as I could do with print. But I couldn't find the right way to do it? Of course I could stick with print, but I would like to understand what I did wrong in case of printf?

推荐答案

每个变量都需要一个格式字符串，例如%s.因此，请尝试:

You need one format string, like %s, for every variable. So, try:

printf "%s %s\n", a, a_counter

或者:

printf "pattern=%s and count=%s\n", a, a_counter

%s将任何变量转换为字符串.如果变量是数字，则其他格式(如%f或%e)可让您更好地控制将数字转换为字符串的方式.有关详细信息，请参见man awk.

%s converts any variable to a string. If the variable is a number, other formats, like %f or %e, give you more control over how the number is converted to a string. See man awk for details.

$ awk -v a="genie" -v a_counter=3 'BEGIN{ printf "%s %s\n", a, a_counter }' 
genie 3
$ awk -v a="genie" -v a_counter=3 'BEGIN{ printf "pattern=%s and count=%s\n", a, a_counter }' 
pattern=genie and count=3
$ awk -v a="genie" -v a_counter=3 'BEGIN{ printf "pattern=%s and count=%7.2f\n", a, a_counter }' 
pattern=genie and count=   3.00
$ awk -v a="genie" -v a_counter=3 'BEGIN{ printf "pattern=%s and count=%9.2e\n", a, a_counter }' 
pattern=genie and count= 3.00e+00

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