Linux sort Command: Sorting Text File Lines in the Terminal

The sort command in Linux sorts the lines of a file. After sorting, a file can be processed by other commands, such as removing duplicate occurrences with the uniq command.

Its options are:

• -b: Ignores spaces at the beginning of the line;
• -d: Sorts lines alphabetically and ignores punctuation;
• -f: Ignores the difference between uppercase and lowercase;
• -I: Ignores control characters;
• -h: Sort in human-readable format
• -m: Merges two or more files into a sorted output file;
• -M: Treats the first three letters of lines as month (e.g., JAN);
• -n: Sorts by numbers at the beginning of lines;
• -r: Sorts in reverse order;
• -u: If the line is duplicated, shows only the first one;
• -o: Sends the command output to the file.

For example, let's sort an email file:

$ sort emails 
[email protected]@[email protected]@[email protected]@[email protected]@empresa.com

One caution should be taken when sorting numbers. See the example of the unsorted file below:

$ cat numeros 330404331191

When using sort without any parameter, it sorts first using the first byte, then the second:

$ sort numeros 119331330440

To sort using numbers as characters, you can use the -n option, or the -h option to sort in human-readable format:

$ sort -n numeros 134193140330

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