sudo操作

在非root权限下，无法执行 vim /etc/profile 并保存，提示如下错误：

"profile" E212: Can't open file for writing

Press ENTER or type command to continue

但是可以执行 sudo vim /etc/profile 并保存。

sudo的作用大体可以理解为：

为非root用户赋予一些root用户才有的操作权限。

只有在/etc/profile有记录的用户才能执行sudo操作

将当前用户设置成 管理员（在当前操作系统中设置）即可使用sudo操作。

当然，不使用sudo，而是直接su root，真正获取root权限也可以执行 vim /etc/profile

eg:

cat /etc/sudoers

权限不足，提示如下所示：

cat: /etc/sudoers: Permission denied

但是可以 sudo cat /etc/sudoers

输入如下结果：

#

# Sample /etc/sudoers file.

#

# This file MUST be edited with the 'visudo' command as root.

#

# See the sudoers man page for the details on how to write a sudoers file.

##

# Override built-in defaults

##

Defaults env_reset

Defaults env_keep += "BLOCKSIZE"

Defaults env_keep += "COLORFGBG COLORTERM"

Defaults env_keep += "__CF_USER_TEXT_ENCODING"

Defaults env_keep += "CHARSET LANG LANGUAGE LC_ALL LC_COLLATE LC_CTYPE"

Defaults env_keep += "LC_MESSAGES LC_MONETARY LC_NUMERIC LC_TIME"

Defaults env_keep += "LINES COLUMNS"

Defaults env_keep += "LSCOLORS"

Defaults env_keep += "SSH_AUTH_SOCK"

Defaults env_keep += "TZ"

Defaults env_keep += "DISPLAY XAUTHORIZATION XAUTHORITY"

Defaults env_keep += "EDITOR VISUAL"

Defaults env_keep += "HOME MAIL"

Defaults lecture_file = "/etc/sudo_lecture"

##

# User alias specification

##

# User_Alias FULLTIMERS = millert, mikef, dowdy

##

# Runas alias specification

##

# Runas_Alias OP = root, operator

##

# Host alias specification

##

# Host_Alias CUNETS = 128.138.0.0/255.255.0.0

# Host_Alias CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0

# Host_Alias SERVERS = master, mail, www, ns

# Host_Alias CDROM = orion, perseus, hercules

##

# Cmnd alias specification

##

# Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less

##

# User specification

##

# root and users in group wheel can run anything on any machine as any user

root ALL = (ALL) ALL

%admin ALL = (ALL) ALL

## Read drop-in files from /private/etc/sudoers.d

## (the '#' here does not indicate a comment)

#includedir /private/etc/sudoers.d