grep : 多行 + 正向前瞻

Question

我有以下几行：

[37125.641615] CPU3 is up
[37125.643067] ACPI: Waking up from system sleep state S3
[37125.683813] ACPI: EC: interrupt unblocked
[37125.684233] pci 0000:01:00.0: Enabling HDA controller
[37125.714885] ACPI: EC: event unblocked
[37125.714931] usb usb2: root hub lost power or was reset
[37125.714935] usb usb4: root hub lost power or was reset
[37125.715046] ath: phy0: ASPM enabled: 0x42
[37125.715389] usb usb1: root hub lost power or was reset
[37125.716515] usb usb3: root hub lost power or was reset

以下是我要匹配的内容（我希望匹配以 ACPI 开头并以第一个 USB 出现为分隔，USB 出现不得匹配）

ACPI: Waking up from system sleep state S3
[37125.683813] ACPI: EC: interrupt unblocked
[37125.684233] pci 0000:01:00.0: Enabling HDA controller
[37125.714885] ACPI: EC: event unblocked
[37125.714931]

我尝试了以下命令：

grep -izoP  'ACPI.*(?=usb)' ~/tmp/dmesg_grep_test

=> 不匹配，为什么？

然后我使用多行 grep 和正向前瞻尝试了这个命令：

grep -izoP  '(?s)ACPI.*(?=usb)' ~/tmp/dmesg_grep_test 
ACPI: Waking up from system sleep state S3
[37125.683813] ACPI: EC: interrupt unblocked
[37125.684233] pci 0000:01:00.0: Enabling HDA controller
[37125.714885] ACPI: EC: event unblocked
[37125.714931] usb usb2: root hub lost power or was reset
[37125.714935] usb usb4: root hub lost power or was reset
[37125.715046] ath: phy0: ASPM enabled: 0x42
[37125.715389] usb usb1: root hub lost power or was reset
[37125.716515] usb 

结果更好...但它与最后一次出现的“usb”匹配结束。我希望它匹配停止“第一次”出现“usb”。 什么是正确的 grep 命令？

PS：我用一个使用 grep 工具的简单示例来问这个问题。事实上，我正在尝试使用 pdfgrep 在一些 pdf 文件中找到类似的模式（多行 + 正向前瞻）。这就是答案需要使用 grep 工具。 谢谢

Answer 1

您可以将此gnu grep 正则表达式与(?s) 或单行模式一起使用：

grep -izoP '(?s)\bACPI:.*?(?=\susb\b)' file

ACPI: Waking up from system sleep state S3
[37125.683813] ACPI: EC: interrupt unblocked
[37125.684233] pci 0000:01:00.0: Enabling HDA controller
[37125.714885] ACPI: EC: event unblocked
[37125.714931]

RegEx Demo

RegEx 解释：

• (?s)：开启单行模式：
• \b：字边界
• ACPI: 匹配ACPI:
• .*?：匹配 0 个或多个任意字符，包括换行符（非贪婪）
• (?=\susb\b)：积极的前瞻性断言我们前面有一个词usb