Shell Programming and Scripting

That's because characters sort below digits. And it would surprise me if the outputs of the two commands were different.
To obtain the desired result with the header on top of the data, try

Code:

head -1 test.csv; tail -n+2 test.csv | sort -t, -k2

Hi, RudiC

Thanks for your help. Would you mind to explain those script to me? I don't understand yet about it. Thanks in advance.

Regards,
Intan

---------- Post updated at 12:36 AM ---------- Previous update was at 12:25 AM ----------

Hi, Don Cragun

Thanks for your help. Would you mind to explain those script to me? I am getting confused about this part:

Code:

-k2.1,2.4n -k2.6,2

I think k2 means the second row of the file. Is that correct? But i don't understand the other yet. Thanks in advance.

Regards,
Intan

Have you tried looking at the man page for the sort, head, and tail utilities?

The command:

Code:

sort -k2.1,2.4n -k2.6,2 -o test.csv -t, test.csv

sorts using a primary sort key that starts with the 1st character in the 2nd field and ends with the 4th character in the second field treating that text as a numeric value (-k2.1,2.4n), using a secondary sort key that starts with the 6th character in the second field and ends with the last character of the second field as an alphanumeric value ( -k2.6,2 ), putting the sorted output into the file test.csv (-o test.csv), using comma as the field delimiter (-t,), and reading input to be sorted from the file test.csv (test.csv).

Using a numeric sort on data that starts with a non-numeric character (in this case, the 1st 4 characters of DateTimeOrigina) is treated as zero (which sorts before the year in the other lines in your file). This makes the heading sort to the beginning of your file instead of the end of your file without having to split out the 1st line of your file (as RudiC did with head -1 test.csv) and sorting the remainder of your input file (head -n+2 test.cv | sort...).

head -1 prints test's first line - the header.
tail -n+2 prints all lines starting with test's second line, then sort -t, -k2 does the rest. You may want to specify the sort keys in more detail, though.