1.同义词
vi ~/.bashrc
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias nt='netstat -anp|grep'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
alias so='source ~/.bashrc'
source ~/.bashrc
netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'