Ubuntu – How to sort lines in a text file from the terminal

Here is a more general approach. Get the output of du folder and du -h folder in two different files.

du folder > file1
du -h folder > file2

The key part is this: concatenate file1 and file2 line by line, with a suitable delimiter.

paste -d '#' file1 file2 > file3

(assuming # does not appear in file1 and file2)

Now sort file3. Note that this will sort based on file1 contents and break ties by file2 contents. Extract the relevant result using cut:

sort -n -k1,7 file3 | cut -d '#' -f 2

Also take a look at man sort for other options.

You may also save this as an alias, for later re-use. To do so, add the following to the bottom of ~/.bashrc:

sorted-du () {
    paste -d '#' <( du "$1" ) <( du -h "$1" ) | sort -n -k1,7 | cut -d '#' -f 2
}

Then, open a new terminal session and execute your new alias:

sorted-du /home

Use the -o option of sort instead of using redirection operator, this will edit the file in place.

From man sort:

-o, --output=FILE
              write result to FILE instead of standard output

Here is a test:

$ cat test.txt 
A
C
B

$ sort test.txt 
A
B
C

$ sort test.txt -o test.txt

$ cat test.txt 
A
B
C