算术运算:
- let 表达式
- $((表达式))
- $[表达式]
运算符:+(加) -(减) *(乘) /(整除) %(求余数)
# let A=1+2
# echo $A
# echo $((2*5))
# echo $[10%3]
手工创建帐号思路:
(1)/etc/passwd (7列)
echo "$ACCOUNT:x:$[$MAXUID+1]:$[$MAXGID+1]::/home/$ACCOUNT:/bin/bash" >> /etc/passwd
(2)/etc/shadow(8列)
chmod u+w /etc/shadow
echo "$ACCOUNT::::::::" >> /etc/shadow
chmod u-w /etc/shadow
(3)/etc/group
echo "$ACCOUNT:x:$[$MAXGID+1]:$ACCOUNT" >> /etc/group
(4)家目录
mkdir /home/$ACCOUNT
cp -a /etc/skel/. /home/$ACCOUNT
chown -R $ACCOUNT:$ACCOUNT /home/$ACCOUNT
chmod 700 /home/$ACCOUNT
(5)邮箱
touch /var/spool/mail/$ACCOUNT
chown $ACCOUNT:mail /var/spool/mail/$ACCOUNT
chmod 660 /var/spool/mail/$ACCOUNT
(6)口令
echo "123" | passwd --stdin $ACCOUNT
如何获取系统当前最大的uid和gid?