遍历多行块的grep输出

Question

当使用-A或-B标志（一次匹配返回多行）时，我无法弄清楚如何从grep输出进行匹配。我不反对为此使用awk，但这将用于检查多个大文件，因此执行时间越短越好。

我认为可以通过使用grep的--group-separator标志并将IFS设置为相同字符来实现此目的，但这似乎并非如此。

$ grep --group-separator=@ -B2 'locked' thisisatest | while IFS=@ read -r match; do 
echo "a" 
echo "${match}"
done
a
this is a test file asdflksdklsdklsdkl.txt
a
this is meaningless
a
this is locked
a

a
this is a test file basdflksdklsdklsdkl.txt
a
this is meaningless
a
this is locked

$ cat thisisatest
this is a test file asdflksdklsdklsdkl.txt
this is meaningless
this is locked
j
j
j
j
j
this is a test file basdflksdklsdklsdkl.txt
this is meaningless
this is locked

我希望在整个比赛之前和之后都打印“ a”，例如：

a
this is a test file asdflksdklsdklsdkl.txt
this is meaningless
this is locked
a

Answer 1

更改$IFS可控制read如何将行拆分为字段。您一次只能填写一个字段（$match），因此字段定界符无关紧要。改为更改行定界符：使用read -d。

grep ... | while read -d@ -r match; do