用户
添加用户
[root@oldboyedu59 ~]# useradd oldboy
[root@oldboyedu59 ~]# id oldboy
uid=1000(oldboy) gid=1000(oldboy) groups=1000(oldboy)
设置密码
[root@oldboyedu59 ~]# passwd oldboy
Changing password for user oldboy.
New password:
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.
切换用户
[root@oldboyedu59 ~]# su - oldboy
[oldboy@oldboyedu59 ~]$ whoami
oldboy
[oldboy@oldboyedu59 ~]$ id
uid=1000(oldboy) gid=1000(oldboy) groups=1000(oldboy)
rw-r--r--的含义
rw-所有者 --r所属用户组 r--其他人（陌生人）
user group other
u g o
rwx-的代表数字和意思
r 4 read 是否可读
w 2 write 是否可写
x 1 executable 是否可以运行 （执行）
- 0
[root@oldboyedu59 oldboy]# ls -l /etc/hosts /bin/ls
-rwxr-xr-x. 1 root root 117680 Oct 31 03:16 /bin/ls
-rw-r--r-- 1 root root 188 Apr 1 17:13 /etc/hosts
-rwxr-xr-x
421401401
7 5 5
-rw-r--r--
420400400
6 4 4
权限与用户的对应关系图：
TIM图片20190411152549.png
例题
755
-rwxr-xr-x. 1 root root 117680 Oct 31 03:16 /bin/ls
750 -rwxr-x---
640 -rw-r-----
604 -rw----r--
644 -rw-r--r--
400 -r--------
修改权限 chmod
[root@oldboyedu59 oldboy]# ls -l oldboy.txt
-rw-r--r-- 2 root root 7 Apr 10 11:57 oldboy.txt
[root@oldboyedu59 oldboy]# chmod 755 oldboy.txt
[root@oldboyedu59 oldboy]# ls -l oldboy.txt
-rwxr-xr-x 2 root root 7 Apr 10 11:57 oldboy.txt
根据字符形式修改权限
[root@oldboyedu59 oldboy]# chmod u-w oldboy.txt
[root@oldboyedu59 oldboy]# ll oldboy.txt
-r--r--r-- 2 root root 7 Apr 10 11:57 oldboy.txt
[root@oldboyedu59 oldboy]# chmod u+w oldboy.txt
[root@oldboyedu59 oldboy]# ll oldboy.txt
-rw-r--r-- 2 root root 7 Apr 10 11:57 oldboy.txt
[root@oldboyedu59 oldboy]# chmod u=w oldboy.txt
[root@oldboyedu59 oldboy]# ll oldboy.txt
--w-r--r-- 2 root root 7 Apr 10 11:57 oldboy.txt
给每个位置都加上执行权限 ugo
[root@oldboyedu59 oldboy]# chmod ugo+x oldboy.txt
[root@oldboyedu59 oldboy]# chmod a-x oldboy.txt
[root@oldboyedu59 oldboy]#
[root@oldboyedu59 oldboy]# ll oldboy.txt
-rw-r--r-- 2 root root 7 Apr 10 11:57 oldboy.txt
[root@oldboyedu59 oldboy]# chmod a+x oldboy.txt
[root@oldboyedu59 oldboy]# ll oldboy.txt
-rwxr-xr-x 2 root root 7 Apr 10 11:57 oldboy.txt
[root@oldboyedu59 oldboy]# chmod a-x oldboy.txt
[root@oldboyedu59 oldboy]# ll oldboy.txt
-rw-r--r-- 2 root root 7 Apr 10 11:57 oldboy.txt
[root@oldboyedu59 oldboy]# chmod +x oldboy.txt
[root@oldboyedu59 oldboy]# ll oldboy.txt
-rwxr-xr-x 2 root root 7 Apr 10 11:57 oldboy.txt
chmod ugo+x oldboy.txt=chmod a+x oldboy.txt
