Linux 在shell中将变量传递给grep
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Passing variable to grep in shell
提问by user2517676
I have written the following shell to count the number of lines starting with the pattern of " A valA B valB". However, I think that I have not passed variables properly. Any help to fix that?
我编写了以下 shell 来计算以“A valA B valB”模式开头的行数。但是，我认为我没有正确传递变量。任何帮助解决这个问题？
for i in {0..16};
do
for j in {0..16};
do
echo A $i B $j
grep '^ A : "$i" B : "$j"' file | wc -l
done
done
采纳答案by konsolebox
Use proper bash quoting. Variables are not expanded inside ''. See the link for reference.
使用正确的bash 引用。变量不在 内部展开''。请参阅链接以供参考。
grep "^ A : $i B : $j" file | wc -l
Also perhaps you mean this, but just try either.
也许你的意思是这个，但试试看。
grep "^ A : \"$i\" B : \"$j\"" file | wc -l
回答by anubhava
- You need right shell quoting (use double quotes for shell's variable expansion)
- You don't need
wc -l, you can directly usegrep -cfor counting the matches
- 您需要正确的 shell 引用（对 shell 的变量扩展使用双引号）
- 你不需要
wc -l，你可以直接grep -c用于计算比赛
You can use:
您可以使用：
grep -c "^ A : $i B : $j" file
