Text processing awk, very cool and powerful

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1. There is a question

输入的文本内容 inputfile ：
a   1
b   2
b   3
c   4
c   5 
c   6
d   7
d   8
d   9
d   10


处理后输出的内容：
a 1
b 5
c 15
d 34
avg 5.5

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Two, two-line solution

 cat inputfile |awk '{s[$1]+=$2}END{for (i in s){print i,s[i]}}'
 cat inputfile |awk '{sum+=$2}END {print "avg " sum/NR}'

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Three, one-line solution

awk  '{s[$1] += $2}END{ for(i in s){ print i, s[i] } }{sum+=$2}END{print "avg ", sum/NR}'   inputfile

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