$ history | awk '{print $2}' | awk 'BEGIN {FS="|"}{print $1}' | sort | uniq -c | sort -n | tail -n 20 | sort -nr
322 ssh
123 cd
96 ls
80 svn
43 awk
36 mysql
34 cat
32 vi
24 man
19 sudo
14 rm
11 elinks
10 /usr/local/bin/mysql
8 gedit
8 echo
8 apt-cache
7 scp
7 ps