Use of sort command in shell

One 、sort How commands work

sort The command takes each line of the file as the comparison object , By comparing different peers , So as to get the final result . The comparison principle is to start with the first character , Press backward in sequence ASCII Code value for comparison , Finally, output the results in ascending order

Compare the previous results ：

[[email protected] programming]$ cat seq.txt
banana
apple
pear
orange

The result after comparison ：

[[email protected] programming]$ sort seq.txt
apple
banana
orange
pear

Two 、sort Command parameters

2.1 sort -u

The function is to remove duplicate lines in the output line

Use only sort Result ：

[[email protected] programming]$ sort seq.txt
apple
banana
orange
pear
pear

add -u Result ：

[[email protected] programming]$ sort -u seq.txt
apple
banana
orange
pear

2.2 sort -r

Role is ,sort The default sorting method of the command is ascending , If you want to change it to descending order , You need to add -r

2.3 sort -o

because sort The default is to output the results to standard output , So redirection is needed to convert the result write file , Form like sort filename > newfile. however , If you want to output the sorting results to In the original document , Not with redirection

As shown below ： This situation will number.txt Empty

[[email protected] programming]$ sort -r number.txt > number.txt
[[email protected] programming]$ cat number.txt
[[email protected] programming]$

Right now ,-o The option appears , It successfully solved this problem , Let you feel free to write the results to the original file

[[email protected] programming]$ cat number.txt
1
3
5
2
4

After using ：

[[email protected] programming]$ sort -r number.txt -o number.txt
[[email protected] programming]$ cat number.txt
5
4
3
2
1

2.4 sort -t And -k

If there is a file like this ：

[[email protected] programming]$ cat facebook.txt
banana:30:5.5
apple:10:2.5
pear:90:2.3
orange:20:3.4

This file has three columns , Columns are separated by colons , The first column shows the type of fruit , The second column shows the number of fruits , The third column shows the price of fruit
So I want to sort by the number of fruits , That is, sort by the second column , How to use it sort Realization ？
fortunately ,sort Provides -t Options , You can set a space character later . After specifying the spacer , You can use it -k To specify the number of columns

[[email protected] programming]$ sort -n -k 2 -t : facebook.txt
apple:10:2.5
orange:20:3.4
banana:30:5.5
pear:90:2.3

We use a colon as a separator , And sort the second column in numerical ascending order , The results are very satisfactory

2.5 Other sort Common options

• -f Will convert all lowercase letters to uppercase letters for comparison , That is, ignore case
• -c Will check if the file is in order , If in disorder , Then output the information about the first disordered row , Finally back to 1
• -C Will check if the file is in order , If in disorder , No output , Return only 1
• -M It will be sorted by month , such as JAN Less than FEB wait
• -b All blanks in front of each line are ignored , Compare from the first visible character