Awk-Group count of field

Shell Programming and Scripting
1

Hi,
Suppose if i am having a file with following records as given below.

  5555
  6756
  5555
  4555
  4555
  6767

how can i get the count of each record using AWK.

Eg:5555 count should be 2
4555 count should be 2
6767 count should be 1

Your help will be really appreciated.

2 
awk ' { arr[$0]++ } END { for( no in arr) { print no , arr[no] } } ' file

sort file | uniq -c
3

Thanks a lot anbu

4 
for i in $(sort file | uniq); do echo "$i has $(grep -c $i file) entries"; done
5

Seems like can use awk and perl command. But I don't have the idea to write the command line. Thanks for all of your advise.
For example, if I have the file whose content are:
Sample 1. ATAGCAGAGGGAGTGAAGAGGTGGTGGGAGGGAGCT
Sample 2. ACTTTTATTTGAATGTAATATTTGGGACAATTATTC
Sample 3. AAATCATGGTGGGTTTATTGATGGTTAGAAAGTTCC
All the sample above, got 36 nucleotide.

I want my output to count the G + C and GC %. So my output should look like this:
Sample 1: G+C = 21 GC%= 58.33%
Sample 2: G+C = 8 GC%=22.22%
Sample 3: G+C = 13 GC%=36.11%

Thanks and appreciate of your answer.

6 
awk '{ for(i=1;i<=n=split($NF,a,"");i++)  if((a=="G")||(a=="C"))  c++;
        printf "%s  GC%%=%.2f%\n",$1 FS $2 FS "G+C=" c , c/n*100; c=0}' file

On Solaris:

nawk '{gsub(/./,"& ",$NF); for(i=1;i<=n=split($NF,a);i++)  if((a=="G")||(a=="C")) c++;
                         printf "%s GC%%=%.2f%\n",$1 FS $2 FS "G+C=" c , c/n*100; c=0}' file