Shell Programming and Scripting

a 1
b 786
c 90709
d 99
a 9875
b 989
c 887
d 111

a 1 9875
b 786 989
c 90709 887
d 99 111

awk '{a[$1]=a[$1]?a[$1] FS $NF:$0}END{for(i in a) print a[i]}' infile | sort

$ cat t.pl 
while(<>)  {
    # take the first word, use it as key and build a hash.
    ( $key, $value ) = /^(\w+)\s+(.*)$/;

    push @{$hash{$key}}, $value;
}

while ( ($key, $value) = each %hash )  {
    print "$key ";
    print "@$value";
    print "\n";
}

$ cat input-file 
a 1
b 786
c 90709
d 99
a 9875
b 989
c 887
d 111
$ perl t.pl input-file
c 90709 887
a 1 9875
b 786 989
d 99 111