linux - 在两个连续行上搜索两个模式并在匹配前打印 n 行

Question

我想使用 shell 命令对匹配两个不同模式的两个连续行进行 grep 或搜索，例如匹配第 1 行:“abc”，第 2 行:“def”。因此，对于以下文本，应该有一个匹配项:第 4 行和第 5 行。

1234
abc-noise
6789
abc-noise
def-noise
def-noise
1234

当我找到这样的匹配时，我想打印它，包括匹配前的 N 行。有任何想法吗？谢谢。

Answer 1

在 PCRE 模式下使用 GNU grep，启用 -P 标志，

grep -ozP ".*abc.*\n.*def.*" file

对输入文件使用pcregrep

cat file
1234
abc-noise
6789
abc-noise
def-noise
def-noise
1234
noise-abc-noise
noise-noise-def

对于多行模式匹配，做

pcregrep -M  'abc.*\n.*def' file 
abc-noise
def-noise
noise-abc-noise
noise-noise-def

对于模式匹配之前的行，使用 -B 标志，如 GNU grep

pcregrep -B2 -M  'abc.*\n.*def' file 
abc-noise
6789
abc-noise
def-noise
def-noise
1234
noise-abc-noise
noise-noise-def

man pcregrep 页面中关于标志 -M 和 -B 的更多信息，

-M, --multiline Allow patterns to match more than one line. When this option is given, patterns may usefully contain literal newline characters and internal occurrences of ^ and $ characters. The output for a successful match may consist of more than one line, the last of which is the one in which the match ended. If the matched string ends with a newline sequence the output ends at the end of that line.

-B number, --before-context=number Output number lines of context before each matching line. If filenames and/or line numbers are being output, a hyphen separator is used instead of a colon for the context lines. A line containing "--" is output between each group of lines, unless they are in fact contiguous in the input file.