# Using sort

sort is a Unix command to order data in file(s) in a sequence.

# Sort command output

sort command is used to sort a list of lines.

Input from a file

sort file.txt

Input from a command

You can sort any output command. In the example a list of file following a pattern.

find * -name pattern | sort

# Make output unique

If each lines of the output need to be unique, add -u option.

To display owner of files in folder

ls -l | awk '{print $3}' | sort -u

# Numeric sort

Suppose we have this file:

test>>cat file
10.Gryffindor
4.Hogwarts
2.Harry
3.Dumbledore
1.The sorting hat

To sort this file numerically, use sort with -n option:

test>>sort -n file

This should sort the file as below:

1.The sorting hat
2.Harry
3.Dumbledore
4.Hogwarts
10.Gryffindor

Reversing sort order: To reverse the order of the sort use the -r option

To reverse the sort order of the above file use:

sort -rn file

This should sort the file as below:

10.Gryffindor
4.Hogwarts
3.Dumbledore
2.Harry
1.The sorting hat

# Sort by keys

Suppose we have this file:

test>>cat Hogwarts
  Harry        Malfoy        Rowena        Helga
  Gryffindor   Slytherin     Ravenclaw     Hufflepuff
  Hermione     Goyle         Lockhart      Tonks
  Ron          Snape         Olivander     Newt
  Ron          Goyle         Flitwick      Sprout

To sort this file using a column as key use the k option:

test>>sort -k 2 Hogwarts

This will sort the file with column 2 as the key:


 Ron        Goyle        Flitwick        Sprout
  Hermione   Goyle        Lockhart        Tonks
  Harry      Malfoy       Rowena          Helga
  Gryffindor Slytherin    Ravenclaw       Hufflepuff
  Ron        Snape        Olivander       Newt

Now if we have to sort the file with a secondary key along with the primary key use:

sort -k 2,2 -k 1,1 Hogwarts

This will first sort the file with column 2 as primary key, and then sort the file with column 1 as secondary key:


 Hermione        Goyle        Lockhart        Tonks
  Ron             Goyle        Flitwick        Sprout
  Harry           Malfoy       Rowena          Helga
  Gryffindor      Slytherin    Ravenclaw       Hufflepuff
  Ron             Snape        Olivander       Newt

If we need to sort a file with more than 1 key , then for every -k option we need to specify where the sort ends. So -k1,1 means start the sort at the first column and end sort at first column.

-t option

In the previous example the file had the default delimeter - tab. In case of sorting a file that has non-default delimeter we need the -t option to specify the delimeter. Suppose we have the file as below:

test>>cat file
5.|Gryffindor
4.|Hogwarts
2.|Harry
3.|Dumbledore
1.|The sorting hat

To sort this file as per the second column, use:

test>>sort -t "|" -k 2 file

This will sort the file as below:

3.|Dumbledore
5.|Gryffindor
2.|Harry
4.|Hogwarts
1.|The sorting hat

# Syntax

sort [option] filename

# Parameters

Option	Meaning
-u	Make each lines of output unique

# Remarks

Full user manual of sort reading online (opens new window)

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