~username:应用另一个用户的家目录
which
basename
dirname
type
file
echo
man
info
whatis
export
ls
hwclock
rmdir
rm
date
cd
pwd
mkdir
cat/tac
head/tail
more/less
nano
touch
cp
mv
finger
useradd
id
groupadd
usermod
groupmod
passwd
chage
newgrp
chmod
chown
chgrp
userdel
umask
declare
printenv
clear
原文：http://benzyi.blog.51cto.com/8731267/1388445