25条awk命令和技巧

注：红色系标记的命令行是测试通过，并从终端复制下来的。蓝色标记的命令行是可行但未试过的。蓝色中文是手动加的注释。未标记颜色的命令行未测试。

第13条按k，m，g统计目录大小，很有学习价值。
源：25 Best AWK Commands / Tricks

1)  List of commands you use most often

history | awk '{a[$2]++} END {for (i in a){print a[i]" "i} }' | sort -nr | head

和第16条的结果一样。

2) Display a block of text with AWK

awk '/start_pattern

/,/stop_patern/' file.txt

I find this terribly useful for grepping through a file, looking for just a block of text. There’s “grep -A # pattern file.txt” to see a specific number of lines following your pattern, but what if you want to see the whole block? Say, the output of “dmidecode” (as root):

dmidecode | awk '/Battery/,/^$/'Will show me everything following the battery block up to the next block of text. Again, I find this extremely useful when I want to see whole blocks of text based on a pattern, and I don’t care to see the rest of the data in output. This could be used against the ‘/etc/securetty/user’ file on Unix to find the block of a specific user. It could be used against VirtualHosts or Directories on Apache to find specific definitions. The scenarios go on for any text formatted in a block fashion. Very handy.

显示某2个模式匹配以及2者之间的所有行。

使用sed实现

sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' file.txt

3) Graph # of connections for each hosts.

netstat -an | grep ESTABLISHED | awk '{print $5}' | awk -F: '{print $1}' | sort | uniq -c | awk '{printf ("%s\t%s\t",$2,$1); for (i=0;i < $1;i++){print "*"};print " "}'

Written for linux, the real example is how to produce ascii text graphs based on a numeric value (anything where uniq -c is useful is a good candidate).

用*的个数来显示来自某个ip的连接数多少。每打印一个*就会换行，看起来不爽，命令需要改进。

4) Check your unread Gmail from the command line

curl -u username:password –silent “” | tr -d ‘\n’ | awk -F ” ‘{for (i=2; i<=NF; i++) {print $i}}’ | sed -n “s/\(.*\)<\/title.*name>\(.*\)<\/name>.*/\2 – \1/p”

Checks the Gmail ATOM feed for your account, parses it and outputs a list of unread messages.

For some reason sed gets stuck on OS X, so here’s a Perl version for the Mac:

curl -u username:password --silent "" | tr -d '\n' | awk -F '' '{for (i=2; i<=NF; i++) {print $i}}' | perl -pe 's/^