How to use Sort Command in Linux

Sort command sorts the lines of a text file. Following are several practical
examples on how to use the sort command based on the following sample text
file that has employee information in the format:

employee_name:employee_id:department_name.

$ cat names.txt
Emma Thomas:100:Marketing
Alex Jason:200:Sales
Madison Randy:300:Product Development
Sanjay Gupta:400:Support
Nisha Singh:500:Sales

Sort a text file in ascending order
$ sort names.txt
Alex Jason:200:Sales
Emma Thomas:100:Marketing
Madison Randy:300:Product Development
Nisha Singh:500:Sales
Sanjay Gupta:400:Support
Sort a text file in descending order

$ sort -r names.txt
Sanjay Gupta:400:Support
Nisha Singh:500:Sales
Madison Randy:300:Product Development
Emma Thomas:100:Marketing
Alex Jason:200:Sales
Sort a colon delimited text file on 2nd field (employee_id)

$ sort -t: -k 2 names.txt
Emma Thomas:100:Marketing
Alex Jason:200:Sales
Madison Randy:300:Product Development
Sanjay Gupta:400:Support
Nisha Singh:500:Sales
Sort a tab delimited text file on 3rd field (department_name) and
suppress duplicates

$ sort -t: -u -k 3 names.txt
Emma Thomas:100:Marketing
Madison Randy:300:Product Development
Alex Jason:200:Sales
Sanjay Gupta:400:Support
Sort the passwd file by the 3rd field (numeric userid)

$ sort -t: -k 3n /etc/passwd | more
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
Sort /etc/hosts file by ip-addres

$ sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n /etc/hosts
127.0.0.1 localhost.localdomain localhost
192.168.100.101 dev-db.thegeekstuff.com dev-db
192.168.100.102 prod-db.thegeekstuff.com prod-db
192.168.101.20 dev-web.thegeekstuff.com dev-web
192.168.101.21 prod-web.thegeekstuff.com prod-web
Combine sort with other commands

o ps –ef | sort : Sort the output of process list
o ls -al | sort +4n : List the files in the ascending order of the file-
 size. i.e sorted by 5th filed and displaying smallest files first.
o ls -al | sort +4nr : List the files in the descending order of the
 file-size. i.e sorted by 5th filed and displaying largest files first.