Question

我想搜索某个图案（比如条线），还要在图案的上方和下方（即1行）打印线条或在图案上方和下方打印2条线。

Foo  line
Bar line
Baz line

....

Foo1 line
Bar line
Baz1 line

....

Answer 1

使用带有grep和-A参数的-B来表示您想要在模式周围打印的行A和B的行数a ：

grep -A1 -B1 yourpattern file

An代表“匹配后的n行”。
Bm代表“匹配前的m行”。

如果两个数字相同，只需使用-C：

grep -C1 yourpattern file

测试

$ cat file
Foo  line
Bar line
Baz line
hello
bye
hello
Foo1 line
Bar line
Baz1 line

我们grep：

$ grep -A1 -B1 Bar file
Foo  line
Bar line
Baz line
--
Foo1 line
Bar line
Baz1 line

要删除组分隔符，您可以使用--no-group-separator：

$ grep --no-group-separator -A1 -B1 Bar file
Foo  line
Bar line
Baz line
Foo1 line
Bar line
Baz1 line

来自man grep：

   -A NUM, --after-context=NUM
          Print NUM  lines  of  trailing  context  after  matching  lines.
          Places   a  line  containing  a  group  separator  (--)  between
          contiguous groups of matches.  With the  -o  or  --only-matching
          option, this has no effect and a warning is given.

   -B NUM, --before-context=NUM
          Print  NUM  lines  of  leading  context  before  matching lines.
          Places  a  line  containing  a  group  separator  (--)   between
          contiguous  groups  of  matches.  With the -o or --only-matching
          option, this has no effect and a warning is given.

   -C NUM, -NUM, --context=NUM
          Print NUM lines of output context.  Places a line  containing  a
          group separator (--) between contiguous groups of matches.  With
          the -o or --only-matching option,  this  has  no  effect  and  a
          warning is given.

Answer 2

grep是适合您的工具，但可以使用awk

完成

awk '{a[NR]=$0} $0~s {f=NR} END {for (i=f-B;i<=f+A;i++) print a[i]}' B=1 A=2 s="Bar" file

注意，这也会找到一个。

或grep

grep -A2 -B1 "Bar" file

如何grep某个模式上下的行

2 个答案:

测试