如果我使用单引号将 awk 的 action 语句括起来，它会按预期工作：
$ dpkg -l | grep "linux\-[a-z]*\-" | awk {'print $2'}
linux-headers-3.13.0-27
linux-headers-3.13.0-27-generic
linux-headers-3.14.4-031404
linux-headers-3.14.4-031404-generic
linux-headers-generic
linux-image-3.13.0-27-generic
linux-image-3.14.4-031404-generic
linux-image-extra-3.13.0-27-generic
linux-image-generic
linux-libc-dev:i386
linux-sound-base
但是如果我使用双引号将它们括起来，它会打印整行而不是特定的列/字段：
$ dpkg -l | grep "linux\-[a-z]*\-" | awk {"print $2"}
ii linux-headers-3.13.0-27 3.13.0-27.50 all Header files related to Linux kernel version 3.13.0
ii linux-headers-3.13.0-27-generic 3.13.0-27.50 i386 Linux kernel headers for version 3.13.0 on 32 bit x86 SMP
ii linux-headers-3.14.4-031404 3.14.4-031404.201405130853 all Header files related to Linux kernel version 3.14.4
ii linux-headers-3.14.4-031404-generic 3.14.4-031404.201405130853 i386 Linux kernel headers for version 3.14.4 on 32 bit x86 SMP
ii linux-headers-generic 3.13.0.27.33 i386 Generic Linux kernel headers
ii linux-image-3.13.0-27-generic 3.13.0-27.50 i386 Linux kernel image for version 3.13.0 on 32 bit x86 SMP
ii linux-image-3.14.4-031404-generic 3.14.4-031404.201405130853 i386 Linux kernel image for version 3.14.4 on 32 bit x86 SMP
ii linux-image-extra-3.13.0-27-generic 3.13.0-27.50 i386 Linux kernel extra modules for version 3.13.0 on 32 bit x86 SMP
ii linux-image-generic 3.13.0.27.33 i386 Generic Linux kernel image
ii linux-libc-dev:i386 3.13.0-27.50 i386 Linux Kernel Headers for development
ii linux-sound-base 1.0.25+dfsg-0ubuntu4 all base package for ALSA and OSS sound systems
为什么会这样？为什么使用双引号将 awk 的操作语句括起来与使用单引号将它们括起来会产生不同的结果？我可以做一些事情，以便使用双引号括起来就像使用单引号括起来一样吗？
如果您使用双引号，则会在调用$2之前awk被shell 替换。因为$2通常是空运行
awk {"print $2"}
和跑步一样
awk {"print "}
用
awk {"print \$2"}
如果你想使用双引号。