練習：
提供十個用戶user1到user10；如果是add，添加用戶,求密碼同用戶名，只有用戶不存在的情況下才能添加；如果是del，刪除用戶以及家目錄；如果是其他直接退出
#!/bin/bash
if [ $# -lt 1 ]; then
????? echo "Usage:test1? [add] or[del]"
????? exit 7
fi
if [ $1 == 'add'?];then
????? for I in {1..10};do
???????????? if id user$I&>/dev/null;then
??????????????????? echo"The user$I ?isexist"
???????????? else
??????????????????? useradd user$I
??????????????????? echo user$I ?| passwd --stdinuser$I ?&>/dev/null
??????????????????? echo "add user$I finished"
????? done
elif [ $1 ==?'del' ?];then
????? for I in {1..10};do
???????????? if id user$I &>/dev/null;then
??????????????????? userdel -r user$I
??????????????????? echo "delete user$I finished"
???????????? else
??????????????????? echo "The user$I isnoexist"?????????????????
????? done
else
????? echo "Unknown Parameter"
????? exit 9
fi
組合條件測試：
-a：與關(guān)系
-o：或關(guān)系
!：取反
例如：大于等于1并且小于3
if [ $# -gt 1 –a?$# -le 3 ]或者if[$# -gt 1 ] && [$# -le 3 ]
