我试图弄清楚如何从由分隔的多行记录中提取特定字段\n\n。
\n\n
在这种情况下，它恰巧是从apt-cache类似于DEBIAN控制文件输出的。查看输出apt-cache show "$package"
apt-cache show "$package"
Package: caffeine Priority: optional Section: misc Installed-Size: 641 Maintainer: Reuben Thomas <rrt@sc3d.org> Architecture: all Version: 2.8.3 Depends: python3:any (>= 3.3.2-2~), python3, gir1.2-gtk-3.0, gir1.2-appindicator3-0.1, python3-xlib, python3-pkg-resources, libnet-dbus-perl Filename: pool/main/c/caffeine/caffeine_2.8.3_all.deb Size: 58774 MD5sum: 4438db3f6d1cf43a4f4b49cc7f24cda0 SHA1: e748370ac5ccd7de6fc9466ce0451d2e90d179d4 SHA256: ae303b4e32949cc1e1af80df7217e3406291679e3f18fa8f78a5bbb97504c4f6 Description-en: Prevent the desktop becoming idle in full-screen mode Caffeine stops the desktop becoming idle when an application is running full-screen. A desktop indicator ‘caffeine-indicator’ supplies a manual toggle, and the command ‘caffeinate’ can be used to prevent idleness for the duration of any command. Description-md5: 7c14f8adc007b10f6ecafed36260bedb Package: caffeine Priority: optional Section: misc Installed-Size: 655 Maintainer: Reuben Thomas <rrt@sc3d.org> Architecture: all Version: 2.6+555~ubuntu14.04.1 Depends: python:any (<< 2.8), python:any (>= 2.7.5-5~), python, gir1.2-gtk-2.0, gir1.2-appindicator3-0.1, x11-utils, python-dbus Filename: pool/main/c/caffeine/caffeine_2.6+555~ubuntu14.04.1_all.deb Size: 58604 MD5sum: 1051c3f7d40d344f986bb632d7436849 SHA1: 5e5f622595e8cbba8fb7468b3cffe2914b0ba110 SHA256: 11c5bbf2d28dcda6a7b82872195f740f1f79521b60d3c9acea3037bf0ab3a60e Description: Prevent the desktop becoming idle Caffeine allows the user to prevent the desktop becoming idle, either manually or when certain applications are run. This prevents screen-blanking, locking, suspending, and so on. Description-md5: 738866350e5086e77408d7a9c7ffa59b Package: caffeine Status: install ok installed Priority: optional Section: misc Installed-Size: 794 Maintainer: Isaiah Heyer <freshapplepy@gmail.com> Architecture: all Version: 2.4.1+478~raring1 Depends: dconf-gsettings-backend | gsettings-backend, python (>= 2.6), python-central (>= 0.6.11), python-xlib, python-appindicator, python-xdg, python-notify, python-kaa-metadata Description: Caffeine A status bar application able to temporarily prevent the activation of both the screensaver and the "sleep" powersaving mode. Description-md5: 1c29acf1ab0f2e6636db29fbde1d14a3 Homepage: https://launchpad.net/caffeine Python-Version: >= 2.6
我想要的输出是格式中的每条记录一行apt-get download $pkg=$ver -a=$arch。基本上是可用软件包的安装命令列表…
apt-get download $pkg=$ver -a=$arch
到目前为止，我所拥有的是 apt-cache show "$package" | awk '/^Package: / { print $2 } /^Version: / { print $2 } /^Architecture: / { print $2 }' | xargs -n3 | awk '{printf "apt-get download %s=%s -a=%s\n", $1, $3, $2}'
apt-cache show "$package" | awk '/^Package: / { print $2 } /^Version: / { print $2 } /^Architecture: / { print $2 }' | xargs -n3 | awk '{printf "apt-get download %s=%s -a=%s\n", $1, $3, $2}'
这是实际输出：
apt-get download caffeine=2.8.3 -a=all apt-get download caffeine=2.6+555~ubuntu14.04.1 -a=all apt-get download caffeine=2.4.1+478~raring1 -a=all
是所需的，但似乎只是a幸，因为在此示例中字段的顺序是一致的。如果字段的顺序不同，则会中断。
我可以在Python中使用面向对象来进行此类解析，但是我很难在一个awk命令中完成此操作。我看到正确执行此操作的唯一方法是将每个记录拆分为单独的tmp文件（使用split或沿这些行的内容），然后分别解析每个文件（这很简单）。显然，我真的很想避免不必要的I / O，因为awk似乎已为此做好了准备。任何awk专业人士都知道如何解决此问题？我什至愿意接受Perl单线脚本或使用bash，但我真的对学习如何更好地利用awk感兴趣。
$ package=sed $ apt-cache show "$package" | awk '/^Package: /{p=$2} /^Version: /{v=$2} /^Architecture: /{a=$2} /^$/{print "apt-get download "p"="v" -a="a}' apt-get download sed=4.2.1-10 -a=amd64
/^Package: /{p=$2}
将软件包信息保存在variable中p。
p
/^Version: /{v=$2}
将版本信息保存在variable中v。
v
/^Architecture: /{a=$2}
将体系结构信息保存在variable中a。
a
/^$/{print "apt-get download "p"="v" -a="a}
当我们到达空白行时，以所需的形式打印出信息。
我的版本apt-cache总是在每个软件包后输出空白行。您的示例输出缺少最后一个空白行。如果您apt- cache确实没有产生最后的空白行，那么我们将需要添加更多代码来进行补偿。
apt-cache
apt- cache
作为一个风格问题，有些人可能更喜欢printf到print。在这种情况下，请将以上内容替换为：
printf
print
/^$/{printf "apt-get download %s=%s -a=%s\n",v,p,a}'
