use unix commands to filter and sort data

Let's say I have data as开发者_JS百科 below:

aaa m7
aaa m9
aaa m7
aaa m7
aaa m7
ccc m9
ccc m7
ccc m7
bbb m7
bbb m9
bbb m7
ddd m7

How could I sort it into:

aaa m9
bbb m9
ccc m9
ddd m7

using unix commands (sort, uniq, etc.)?

What I need is sort all data and then filter out all data with same field#1.

This takes your input and gives your output. I'm not sure whether it's what you want, given the vagueness of your specification...

$ cat ./4162059.awk 
#!/usr/bin/awk -f

{
    if (d[$1] < $2) {
        d[$1] = $2
    }
}

END {
    for (k in d) {
       print k " " d[k]
    }
}

$ cat ./4162059.txt 
aaa m7
aaa m9
aaa m7
aaa m7
aaa m7
ccc m9
ccc m7
ccc m7
bbb m7
bbb m9
bbb m7
ddd m7

$ ./4162059.awk 4162059.txt | sort
aaa m9
bbb m9
ccc m9
ddd m7

The awk program keeps note of the value of the column 1 with the 'highest' value of column 2 and prints them once it has parsed the whole input file. The output is then sorted by sort on the command-line.

If the data resides in data.txt, use:

sort < data.txt > sorted.txt

If you just want the m9's, use:

grep m9 < data.txt | sort | uniq > sorted_m9.txt

It's not very clear what you want to do.

I'm assuming you want to print only unique values in column 1 with the largest corresponding value in column 2 because your output has m9.

sort -V input | 
perl -nae '$H{$F[0]}=$F[1];END{for(sort keys %H){print $_." ".$H{$_}."\n";}}'

Sample run:

$ cat file
aaa m9
aaa m10
ccc m9
ccc m7
bbb m7
bbb m9
bbb m7
ddd m11
ddd m1
$ sort -V file | perl -nae '$H{$F[0]} = $F[1];END{for(sort keys %H){print $_." ".$H{$_}."\n";}}'
aaa m10
bbb m9
ccc m9
ddd m11
$