Many ways to sort file content on Linux

The Linux sort command can arrange command output or file content in a lot more ways than you might realize–alphabetically, numerically, by month and randomly are only some of the more interesting choices. In this post, we take a look at some of the more useful sorting options and explain how they differ.

The default

The default sort might seem fairly straightforward. Digits come first, followed by letters and, for each letter, lowercase characters precede uppercase characters. You can expect to see this kind of ordering:

012345aAbBcCdDeE

ASCII order

Looking at the numeric byte values for each of these letters, you may note that what you see above is not the “natural order” as far as ASCII is concerned.

$ echo 012345aAbBcCdDeE | od -bc
0000000 060 061 062 063 064 065 141 101 142 102 143 103 144 104 145 105
          0   1   2   3   4   5   a   A   b   B   c   C   d   D   e   E

As you’ll notice in this octal dump of the list of characters, uppercase letters have lower ASCII values and would come before lowercase letters if they were listed in ASCII order. To sort by byte value, prepend your sort command with LC_ALL=C. For example, here’s a comparison of sorting in byte order compared with the default sort  order:

$ LC_ALL=C sort file		$ sort file
0				0
1				1
2				2
3				3
4				4
5				5
A <==				a <==
B <==				A <==
C				b
D				B
E				c
a				C
b				d
c				D
d				e
e				E

Numeric order

To sort numerically, you need to use -n or you’ll end up sorting numbers by character and 100 would pretend to be smaller than 2. Here’s a comparison between a default sort and a numeric sort: