If this is UNIX:
sort -k 2 file.txt
You can use multiple -k flags to sort on more than one column. For example, to sort by family name then first name as a tie breaker:
sort -k 2,2 -k 1,1 file.txt
Relevant options from "man sort":
-k, --key=POS1[,POS2]
start a key at POS1, end it at POS2 (origin 1)
POS is F[.C][OPTS], where F is the field number and C the character position in the field. OPTS is one or more single-letter ordering options, which override global ordering options for that key. If no key is given, use the entire line as the key.
-t, --field-separator=SEP
use SEP instead of non-blank to blank transition
FWIW, here is a sort method for showing which processes are using the most virt memory.
memstat | sort -k 1 -t':' -g -r | less
Sort options are set to first column, using : as column seperator, numeric sort and sort in reverse.
sort -nk2 file.txt
Accordingly you can change column number.
To sort by second field only (thus where second fields match, those lines with matches remain in the order they are in the original without sorting on other fields) :
sort -k 2,2 -s orig_file > sorted_file
Source: Stackoverflow.com