The sort command in Linux arranges lines in a file or input based on various criteria, such as alphabetical order, numerical order, and more. It’s commonly used for data processing, where sorting a file or output in a specific order is required.

Basic Syntax

sort [options] filename

Common Options

• -r : Sorts in reverse order.
• -n : Sorts by numeric value.
• -k : Specifies a column (or field) to sort by.
• -u : Removes duplicate lines.
• -t : Specifies a delimiter for sorting by fields (default is whitespace).

Examples with Output

Example 1: Sorting a File Alphabetically

Suppose file.txt contains:

banana
apple
cherry
date

Command

sort file.txt

Output

apple
banana
cherry
date

Explanation:

• sort file.txt arranges the lines alphabetically in ascending order.

Example 2: Sorting in Reverse Order

You can reverse the order of sorting using -r.

Command

sort -r file.txt

Output

date
cherry
banana
apple

Explanation:

• sort -r file.txt sorts the lines in reverse alphabetical order.

Example 3: Sorting Numerically

For files with numbers, use -n to sort based on numeric values.

Suppose numbers.txt contains:

10
1
20
2

Command

sort -n numbers.txt

Output

1
2
10
20

Explanation:

• sort -n treats each line as a number, sorting numerically.

Example 4: Sorting by a Specific Column

Suppose data.txt contains two columns of data separated by spaces:

apple 3
banana 1
cherry 2
date 5

Command

sort -k 2 data.txt

Output

banana 1
cherry 2
apple 3
date 5

Explanation:

• -k 2 sorts based on the second column, which is the numeric values in this case.

Example 5: Sorting by a Delimited Field

If fields are separated by a specific delimiter, use -t with -k.

Suppose data.csv contains:

apple,3
banana,1
cherry,2
date,5

Command

sort -t ',' -k 2 data.csv

Output

banana,1
cherry,2
apple,3
date,5

Explanation:

• -t ',' specifies a comma as the delimiter.
• -k 2 sorts by the second field, which is the numeric value after the comma.

Example 6: Removing Duplicate Lines

If a file has duplicate lines, -u can remove them while sorting.

Suppose duplicates.txt contains:

apple
banana
apple
cherry
banana

Command

sort -u duplicates.txt

Output

apple
banana
cherry

Explanation:

• sort -u removes duplicate lines, leaving only unique entries in sorted order.

Summary of Common sort Commands

The sort command is an essential tool for organizing and managing data, particularly in scripts and data processing workflows.