[root@localhost wyb]# cat tishiuser.sh #!/bin/bash #提示用户输入一个用户名，如果存在；显示用户UID和SHELL信息；否则，#则显示无此用户；显示完成之后，提示用户再次输入；如果是quit则退出;echo ‘Input `quit` to quit‘while :do    read -p "Please Input a user:" choice    [ -z $choice ] &&continue    [[ "$choice" = "quit"  ]] && break        id $choice  &> /dev/null   [ $? -eq 0 ] && grep "$choice" /etc/passwd|awk -F ":" ‘{print $3,$NF}‘|| echo "NO this user!"done[root@localhost wyb]# bash tishiuser.sh Input `quit` to quitPlease Input a user:quit[root@localhost wyb]# bash tishiuser.sh Input `quit` to quitPlease Input a user:root0 /bin/bash11 /sbin/nologinPlease Input a user:fineday500 /bin/bashPlease Input a user:bobo501 /bin/bashPlease Input a user:quit[root@localhost wyb]# bash tishiuser.sh Input `quit` to quitPlease Input a user:llkkNO this user!Please Input a user:quit[root@localhost wyb]#