Linux command or script counting duplicated lines in a text file?

If I have a text file with the following conent

red apple
green apple
green apple
orange
orange
orange

Is there a Linux command or script that I can use to get the following result?

1 red apple
2 green apple
3 orange

Send it through sort (to put adjacent items together) then uniq -c to give counts, i.e.:

sort filename | uniq -c

and to get that list in sorted order (by frequency) you can

sort filename | uniq -c | sort -nr

Almost the same as borribles' but if you add the d param to uniq it only shows duplicates.

sort filename | uniq -cd | sort -nr

uniq -c file

and in case the file is not sorted already:

sort file | uniq -c

cat <filename> | sort | uniq -c

Can you live with an alphabetical, ordered list:

echo "red apple
> green apple
> green apple
> orange
> orange
> orange
> " | sort -u 

?

green apple
orange
red apple

or

sort -u FILE

-u stands for unique, and uniqueness is only reached via sorting.

A solution which preserves the order:

echo "red apple
green apple
green apple
orange
orange
orange
" | { old=""; while read line ; do   if [[ $line != $old ]]; then  echo $line;   old=$line; fi ; done }
red apple
green apple
orange

and, with a file

cat file | { 
old=""
while read line
do
  if [[ $line != $old ]]
  then
    echo $line
    old=$line
  fi
done }

The last two only remove duplicates, which follow immediately - which fits to your example.

echo "red apple
green apple
lila banana
green apple
" ...

Will print two apples, split by a banana.

Try this

cat myfile.txt| sort| uniq

To just get a count:

$> egrep -o '\w+' fruits.txt | sort | uniq -c

      3 apple
      2 green
      1 oragen
      2 orange
      1 red

To get a sorted count:

$> egrep -o '\w+' fruits.txt | sort | uniq -c | sort -nk1
      1 oragen
      1 red
      2 green
      2 orange
      3 apple

EDIT

Aha, this was NOT along word boundaries, my bad. Here's the command to use for full lines:

$> cat fruits.txt | sort | uniq -c | sort -nk1
      1 oragen
      1 red apple
      2 green apple
      2 orange

Here is a simple python script using the Counter type. The benefit is that this does not require sorting the file, essentially using zero memory:

import collections
import fileinput
import json

print(json.dumps(collections.Counter(map(str.strip, fileinput.input())), indent=2))

Output:

$ cat filename | python3 script.py
{
  "red apple": 1,
  "green apple": 2,
  "orange": 3
}

or you can use a simple one-liner:

$ cat filename | python3 -c 'print(__import__("json").dumps(__import__("collections").Counter(map(str.strip, __import__("fileinput").input())), indent=2))'