Need some assistance with LINUXUNIX file sorting Consider th

Need some assistance with LINUX/UNIX file sorting

Consider the file whodb created with this command: -bash-3.2$ who > whodb

Part 1: Please show the command to: sort it by date (primary key) and time (secondary key) logged in.

Part 2: Please show the command to: create a new file called useron containing username, date, and time logged in.

Solution

Taking sample data:

Code    Date TIME
AHOS05       23/12/2016   10AM
AHOS06       15/12/2016   2PM
AHOS62       29/12/2016   10AM
AHOS64       23/12/2016   2PM
AHOS70       26/12/2016   10AM
AZFT01       06/12/2016   10AM
AHOS73       11/12/2016   2PM
AMHOS051   05/12/2016   10AM
AMHOS041   20/12/2016   2PM
AMHOS042   27/12/2016   2PM
AMHOS053   11/12/2016   10AM
AMHOS043   30/12/2016   2PM

A) Try using sort command to display lines of its input listed in sorted order.
Special option is there which is called -M to sort months. Total 3 fields are there in which First one is some sort of code, Second one is actual date in DD/MM/YYYY format and third one is time.
As question says, sorting needs to be done using date and time.
So,You need to sort 2nd and 3rd column using -k option of sort commands as follows:

$ sort -k 2,2n -k 3 whodb

Sample Output

AMHOS051   05/12/2016   10AM
AZFT01       06/12/2016   10AM
AMHOS053   11/12/2016   10AM
AHOS73       11/12/2016   2PM
AHOS06       15/12/2016   2PM
AMHOS041   20/12/2016   2PM
AHOS05       23/12/2016   10AM
AHOS64       23/12/2016   2PM
AHOS70       26/12/2016   10AM
AMHOS042   27/12/2016   2PM
AHOS62       29/12/2016   10AM
AMHOS043   30/12/2016   2PM

Where,

-> -k 2,2n -k 3 : Sort data using the given column number.
   The option -k 2,2n -k 3 will sorts each column.
   First, it will sort 2nd column (date dd field) and then 3rd column (time).
-> whodb : Input file