自学教程：Linux sudo命令

Linux sudo命令以系统管理者的身份执行指令，也就是说，经由 sudo 所执行的指令就好像是 root 亲自执行。

使用权限：在 /etc/sudoers 中有出现的使用者。

语法

sudo -V

sudo -h

sudo -l

sudo -v

sudo -k

sudo -s

sudo -H

sudo [ -b ] [ -p prompt ] [ -u username/#uid] -s

sudo command

参数说明：

• -V 显示版本编号
• -h 会显示版本编号及指令的使用方式说明
• -l 显示出自己（执行 sudo 的使用者）的权限
• -v 因为 sudo 在第一次执行时或是在 N 分钟内没有执行（N 预设为五）会问密码，这个参数是重新做一次确认，如果超过 N 分钟，也会问密码
• -k 将会强迫使用者在下一次执行 sudo 时问密码（不论有没有超过 N 分钟）
• -b 将要执行的指令放在背景执行
• -p prompt 可以更改问密码的提示语，其中 %u 会代换为使用者的帐号名称， %h 会显示主机名称
• -u username/#uid 不加此参数，代表要以 root 的身份执行指令，而加了此参数，可以以 username 的身份执行指令（#uid 为该 username 的使用者号码）
• -s 执行环境变数中的 SHELL 所指定的 shell ，或是 /etc/passwd 里所指定的 shell
• -H 将环境变数中的 HOME （家目录）指定为要变更身份的使用者家目录（如不加 -u 参数就是系统管理者 root ）
• command 要以系统管理者身份（或以 -u 更改为其他人）执行的指令

实例

sudo命令使用

$ sudo ls[sudo] password for hnlinux: hnlinux is not in the sudoers file. This incident will be reported.

指定用户执行命令

# sudo -u userb ls -l

显示sudo设置

$ sudo -L //显示sudo设置Available options in a sudoers ``Defaults'' line:syslog: Syslog facility if syslog is being used for loggingsyslog_goodpri: Syslog priority to use when user authenticates successfullysyslog_badpri: Syslog priority to use when user authenticates unsuccessfullylong_otp_prompt: Put OTP prompt on its own lineignore_dot: Ignore '.' in $PATHmail_always: Always send mail when sudo is runmail_badpass: Send mail if user authentication failsmail_no_user: Send mail if the user is not in sudoersmail_no_host: Send mail if the user is not in sudoers for this hostmail_no_perms: Send mail if the user is not allowed to run a commandtty_tickets: Use a separate timestamp for each user/tty combolecture: Lecture user the first time they run sudolecture_file: File containing the sudo lectureauthenticate: Require users to authenticate by defaultroot_sudo: Root may run sudolog_host: Log the hostname in the (non-syslog) log filelog_year: Log the year in the (non-syslog) log fileshell_noargs: If sudo is invoked with no arguments, start a shellset_home: Set $HOME to the target user when starting a shell with -salways_set_home: Always set $HOME to the target user's home directorypath_info: Allow some information gathering to give useful error messagesfqdn: Require fully-qualified hostnames in the sudoers fileinsults: Insult the user when they enter an incorrect passwordrequiretty: Only allow the user to run sudo if they have a ttyenv_editor: Visudo will honor the EDITOR environment variablerootpw: Prompt for root's password, not the users'srunaspw: Prompt for the runas_default user's password, not the users'stargetpw: Prompt for the target user's password, not the users'suse_loginclass: Apply defaults in the target user's login class if there is oneset_logname: Set the LOGNAME and USER environment variablesstay_setuid: Only set the effective uid to the target user, not the real uidpreserve_groups: Don't initialize the group vector to that of the target userloglinelen: Length at which to wrap log file lines (0 for no wrap)timestamp_timeout: Authentication timestamp timeoutpasswd_timeout: Password prompt timeoutpasswd_tries: Number of tries to enter a passwordumask: Umask to use or 0777 to use user'slogfile: Path to log filemailerpath: Path to mail programmailerflags: Flags for mail programmailto: Address to send mail tomailfrom: Address to send mail frommailsub: Subject line for mail messagesbadpass_message: Incorrect password messagetimestampdir: Path to authentication timestamp dirtimestampowner: Owner of the authentication timestamp direxempt_group: Users in this group are exempt from password and PATH requirementspassprompt: Default password promptpassprompt_override: If set, passprompt will override system prompt in all cases.runas_default: Default user to run commands assecure_path: Value to override user's $PATH witheditor: Path to the editor for use by visudolistpw: When to require a password for 'list' pseudocommandverifypw: When to require a password for 'verify' pseudocommandnoexec: Preload the dummy exec functions contained in 'noexec_file'noexec_file: File containing dummy exec functionsignore_local_sudoers: If LDAP directory is up, do we ignore local sudoers fileclosefrom: File descriptors >= %d will be closed before executing a commandclosefrom_override: If set, users may override the value of `closefrom' with the -C optionsetenv: Allow users to set arbitrary environment variablesenv_reset: Reset the environment to a default set of variablesenv_check: Environment variables to check for sanityenv_delete: Environment variables to removeenv_keep: Environment variables to preserverole: SELinux role to use in the new security contexttype: SELinux type to use in the new security contextaskpass: Path to the askpass helper programenv_file: Path to the sudo-specific environment filesudoers_locale: Locale to use while parsing sudoersvisiblepw: Allow sudo to prompt for a password even if it would be visisblepwfeedback: Provide visual feedback at the password prompt when there is user inputfast_glob: Use faster globbing that is less accurate but does not access the filesystemumask_override: The umask specified in sudoers will override the user's, even if it is more permissive

以root权限执行上一条命令

$ sudo !!

以特定用户身份进行编辑文本

$ sudo -u uggc vi ~www/index.html//以 uggc 用户身份编辑  home 目录下www目录中的 index.html 文件

列出目前的权限

sudo -l

列出 sudo 的版本资讯

sudo -V