Sudo (sometimes considered as short for Super-user do) is a program designed to let system administrators allow some users to execute some commands as root (or another user). The basic philosophy is to give as few privileges.Sudoers - Community Help Wiki. Introduction. The /etc/sudoers file controls who can run what commands as what users on what machines and can also control special things such as whether you need a password for particular commands. The file is composed of aliases (basically variables) and user specifications (which control who can run what). Sudo provides a well documented sudoers file that is the first and pretty education example: # Sample /etc/sudoers file. # # This file MUST be edited with the 'visudo' command as root. # # See the sudoers man page for the. My.bak file is the other the local server. I tried too many different script but unable to successes. I tried syntax is RESTORE FILELISTONLY FROM DISK='D:\ERPNewtesting-12022014.bak' Get the. Editing the sudoers file. For Ubuntu 8. 0. 4: The default editor for visudo has changed to vi, which may cause confusion to those who are not familiar to its command bindings. To change this behavior, open your ~/.
EDITOR="nano"If you wish to use another text editor, replace "nano" with any text editor of your choice. Run source ~/. bashrc to ensure the changes you made have taken effect. Now launch visudo with sudo - E visudo in the terminal, and put in Defaults editor=/usr/bin/nano in the file. So the top of the file should now look like this: Defaults editor=/usr/bin/nano. Defaults env_reset. Again, if you wish to use another text editor, replace "nano" with the full path to the text editor of your choice. Save, and from now on launching visudo with gksu visudo for Ubuntu; kdesu visudo for Kubuntu or sudo visudo in the terminal will now open with your chosen editor. For Ubuntu 8. 1. 0: The default editor for visudo has changed to sensible- editor. To setup the default editor for visudo. You will get a prompt to choose which editor you want. Select an editor. To change later, run 'select- editor'. Choose 1- 4 [3]: If you don't consider yourself competent in any of the enlisted terminal- based editors, it is recommended that you choose option 3, nano. Because sudo is such a powerful program you must take care not to put anything formatted incorrectly in the file. To prevent any incorrect formatting getting into the file you should edit it using the command visudo run as root or by using sudo. The sudoers file is read in one pass so when multiple entries match for a user, they are applied in order. Where there are conflicting values, the last match is used (which is not necessarily the most specific match). Also you must set an alias before you can use it. Normally you will set the aliases at the beginning of the file and then set the user specifications after all the aliases are laid out. You can insert comments by prefixing them with a # but this is also used to specify a uid in certain parts of the file when it is followed by a number. Aliases. There are four kinds of aliases: User_Alias, Runas_Alias, Host_Alias and Cmnd_Alias. Each alias definition is of the form: Alias_Type NAME = item. Where Alias_Type is one of User_Alias, Runas_Alias, Host_Alias or Cmnd_Alias. A name is a string of uppercase letters, numbers and underscores starting with an uppercase letter. You can put several aliases of the same type on one line by separating them with colons (: ) as so: Alias_Type NAME1 = item. NAME2 = item. 3 You can include other aliases in an alias specification provided they would normally fit there. For example you can use a user alias wherever you would normally expect to see a list of users (for example in a user or runas alias). There are also built in aliases called ALL which match everything where they are used. If you used ALL in place of a user list it matches all users for example. If you try and set an alias of ALL it will be overridden by this built in alias so don't even try. User Aliases. User aliases are used to specify groups of users. You can specify usernames, system groups (prefixed by a %) and netgroups (prefixed by a +) as follows: # Everybody in the system group "admin" is covered by the alias ADMINS. User_Alias ADMINS = %admin. The users "tom", "dick", and "harry" are covered by the USERS alias. User_Alias USERS = tom, dick, harry. The users "tom" and "mary" are in the WEBMASTERS alias. User_Alias WEBMASTERS = tom, mary. You can also use ! This matches anybody in the USERS alias who isn't in WEBMASTERS or ADMINS aliases. User_Alias LIMITED_USERS = USERS, ! WEBMASTERS, ! ADMINSRunas Aliases. Runas Aliases are almost the same as user aliases but you are allowed to specify users by uid's. This is helpful as usernames and groups are matched as strings so two users with the same uid but different usernames will not be matched by entering a single username but can be matched with a uid. For example: # UID 0 is normally used for root. Note the hash (#) on the following line indicates a uid, not a comment. Runas_Alias ROOT = #0. This is for all the admin users similar to the User_Alias of ADMINS set earlier. Runas_Alias ADMINS = %admin, root. Host Aliases. A host alias is a list of hostname, ip addresses, networks and netgroups (prefixed with a +). If you do not specify a netmask with a network the netmask of the hosts ethernet interface(s) will be used when matching. This is all the servers. Host_Alias SERVERS = 1. This is the whole network. Host_Alias NETWORK = 1. And this is every machine in the network that is not a server. Host_Alias WORKSTATIONS = NETWORK, ! SERVER. # This could have been done in one step with. Host_Alias WORKSTATIONS = 1. SERVERS. # but I think this method is clearer. Command Aliases. Command aliases are lists of commands and directories. You can use this to specify a group of commands. If you specify a directory it will include any file within that directory but not in any subdirectories. The special command '"sudoedit"' allows users to run sudo with the - e flag or as the command sudoedit. If you include command line arguments in a command in an alias these must exactly match what the user enters on the command line. If you include any of the following they will need to be escaped with a backslash (\): ",", "\", ": ", "=". Examples: # All the shutdown commands. Cmnd_Alias SHUTDOWN_CMDS = /sbin/poweroff, /sbin/reboot, /sbin/halt. Printing commands. Cmnd_Alias PRINTING_CMDS = /usr/sbin/lpc, /usr/sbin/lprm. Admin commands. Cmnd_Alias ADMIN_CMDS = /usr/sbin/passwd, /usr/sbin/useradd, /usr/sbin/userdel, /usr/sbin/usermod, /usr/sbin/visudo. Web commands. Cmnd_Alias WEB_CMDS = /etc/init. User Specifications. User Specifications are where the sudoers file sets who can run what as who. It is the key part of the file and all the aliases have just been set up for this very point. If this was a film this part is where all the key threads of the story come together in the glorious unveiling before the final climatic ending. Basically it is important and without this you ain't going anywhere. A user specification is in the format < user list> < host list> = < operator list> < tag list> < command list> The user list is a list of users or a user alias that has already been set, the host list is a list of hosts or a host alias, the operator list is a list of users they must be running as or a runas alias and the command list is a list of commands or a cmnd alias. The tag list has not been covered yet and allows you set special things for each command. You can use PASSWD and NOPASSWD to specify whether the user has to enter a password or not and you can also use NOEXEC to prevent any programs launching shells themselves (as once a program is running with sudo it has full root privileges so could launch a root shell to circumvent any restrictions in the sudoers file. For example (using the aliases and users from earlier) # This lets the webmasters run all the web commands on the machine. WEBMASTERS webserver= WEB_CMDS. This lets the admins run all the admin commands on the servers. ADMINS SERVERS= ADMIN_CMDS. This lets all the USERS run admin commands on the workstations provided. USERS WORKSTATIONS=(ADMINS) ADMIN_CMDS. This lets "harry" shutdown his own machine without a password. NOPASSWD: SHUTDOWN_CMDS. And this lets everybody print without requiring a password. ALL ALL=(ALL) NOPASSWD: PRINTING_CMDSThe Default Ubuntu Sudoers File. The sudoers file that ships with Ubuntu 8. This file MUST be edited with the 'visudo' command as root. See the man page for details on how to write a sudoers file. Defaults env_reset. Uncomment to allow members of group sudo to not need a password. ALL=NOPASSWD: ALL. Host alias specification. User alias specification. Cmnd alias specification. User privilege specification. ALL=(ALL) ALL. # Members of the admin group may gain root privileges. ALL=(ALL) ALLThis is pretty much empty and only has three rules in it. The first (Defaults env_reset) resets the terminal environment after switching to root. So, ie: all user set variables are removed. The second (root ALL=(ALL) ALL) just lets root do everything on any machine as any user. And the third (%admin ALL=(ALL) ALL) lets anybody in the admin group run anything as any user. Note that they will still require a password (thus giving you the normal behaviour you are so used to). If you want to add your own specifications and you are a member of the admin group then you will need to add them after this line. Otherwise all your changes will be overridden by this line saying you (as part of the admin group) can do anything on any machine as any user provided you give a password. Common Tasks. This section includes some common tasks and how to accomplish them using the sudoers file. Shutting Down From The Console Without A Password. Often people want to be able to shut their computers down without requiring a password to do so. This is particularly useful in media PCs where you want to be able to use the shutdown command in the media centre to shutdown the whole computer. To do this you need to add some cmnd aliases as follows: Cmnd_Alias SHUTDOWN_CMDS = /sbin/poweroff, /sbin/halt, /sbin/reboot. You also need to add a user specification (at the end of the file after the "%admin ALL = (ALL) ALL" line so it takes effect - see above for details): < your username> ALL=(ALL) NOPASSWD: SHUTDOWN_CMDSObviously you need to replace "< your username> " with the username of the user who needs to be able to shutdown the pc without a password. You can use a user alias here as normal.
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