Sudo/ja

コマンドは特権の昇格をシンプル・安全に管理します. たとえば一般ユーザーが特定（もしくはすべて）のコマンドをや他のユーザーで（パスワードなしも含め）実行できるようにします.

ユーザーに特権の必要な操作を許可したいがrootは渡したくない、という時にはsudoを使うとよいでしょう. sudoは誰が何をすることができるかを制御できます. それではこの素敵なツールについて簡単に紹介します.

This article is meant as a quick introduction. The package is a lot more powerful than what is described here. It has special features for editing files as a different user, running from within a script (so it can background, read the password from standard in instead of the keyboard, ...), etc.

さらなる情報に関しては、やのマニュアルを参照してください.

Logging activity
One additional advantage of is that it can log any attempt (successful or not) to run an application. This is very useful when tracking who made that one fatal mistake that took 10 hours to fix :)

Granting permissions
The package allows the system administrator to grant permission to other users to execute one or more applications they would normally have no right to. Unlike using the  bit on these applications  gives a more fine-grained control on who can execute a certain command and when.

With a clear list can be made of who can execute a certain application. If the setuid bit is set on an executable, any user would be able to run the application (or any user of a certain group, depending on the permissions used). With the user can (and probably should) be required to provide a password in order to execute the application.

の設定はに書かれています. このファイルを や やその他のエディタで編集してはいけません. 代わりに を使うようにしてください.

基本的な構文
の最も難解な部分がの構文です. 基本的な構文を示します.

この構文では、"host"からログインしている"user"というユーザーは"commands"に上げられたコマンドをrootとして実行してもよい、ということを に示します. "swift"がlocalhostでログインしていたら の実行を許可する、といった現実的な例を考えるとわかりやすいでしょう.

A more real-life example might make this more clear: To allow the user to execute  when he is logged in on :

ユーザー名の代わりにグループ名を使うこともできます. この場合はグループ名の頭に をつけてください. グループのメンバーに の実行を許可する場合はこのように書きます.

コマンドごとに行を増やす代わりに、一行に複数のコマンドを書くこともできます. 例えば先ほどのユーザーに だけでなく と の実行も許可する場合はこう書きます.

The precise command line can also be specified (including parameters and arguments) not just the name of the executable. This is useful to restrict the use of a certain tool to a specified set of command options. The tool allows shell-style wildcards (AKA meta or glob characters) to be used in path names as well as command-line arguments in the sudoers file. Note that these are not regular expressions.

Here is an example of from the perspective of a first-time user of the tool who has been granted access to the full power of :

が要求するパスワードはユーザー自身のパスワードです. この手順を踏むことで、うっかりログインしたまま席を離れてしまった時に不正利用されないようにします.

なお は を変更しません. で実行するコマンドはあなたの環境から実行されます. このため、などに置かれたツールを実行したい時は次のように完全なパスを に渡す必要があります.

Basic syntax with LDAP
The  and   USE flags are needed for the LDAP support.

When using sudo with LDAP, sudo will read configuration from LDAP Server as well. So two files will need to edited.

The following LDAP entry will need to added for sudo.

The configuration on the sudoer on LDAP are similar to files with some different. Please read more about sudo with LDAP on the link below.

エイリアスを用いる
In larger environments having to enter all users over and over again (or hosts, or commands) can be a daunting task. To ease the administration of aliases can defined. The format to declare aliases is quite simple:

One alias that always works, for any position, is the  alias (to make a good distinction between aliases and non-aliases it is recommended to use capital letters for aliases). The  alias is an alias to all possible settings.

A sample use of the  alias to allow any user to execute the  command if he is logged on locally is:

Another example is to allow the user to execute the  command as root, regardless of where he is logged in from:

More interesting is to define a set of users who can run software administrative applications (such as and ) on the system and a group of administrators who can change the password of any user, except root!

Non-root execution
It is also possible to have a user run an application as a different, non-root user. This can be very interesting when running applications as a different user (for instance for the web server) and want to allow certain users to perform administrative steps as that user (like killing zombie processes).

Inside list the user(s) in between   and   before the command listing:

For instance, to allow to run the  tool as the  or  user:

With this set, the user can run to select the user he wants to run the application as:

An alias can set for the user to run an application as using the  directive. Its use is identical to the other  directives we have seen before.

Passwords and default settings
By default, asks the user to identify himself using his own password. Once a password is entered, remembers it for 5 minutes, allowing the user to focus on his tasks and not repeatedly re-entering his password.

Of course, this behavior can be changed: set the  directive in  to change the default behavior for a user.

For instance, to change the default 5 minutes to 0 (never remember):

A setting of  would remember the password indefinitely (until the system reboots).

A different setting would be to require the password of the user that the command should be run as and not the users' personal password. This is accomplished using. In the following example we also set the number of retries (how many times the user can re-enter a password before fails) to   instead of the default 3:

Another interesting feature is to keep the  variable set so that graphical tools can be executed:

Dozens of default settings can changed using the  directive. Fire up the manual page and search for.

To allow a user to run a certain set of commands without providing any password whatsoever, start the commands with, like so:

Bash completion
Users that want bash completion with sudo need to run this once.

Zshell completion
Users that want zsh completion for sudo can set the following in and  respectively

With the above change, all commands in the, and  locations will be available to the shell for completion when the command is prefaced with 'sudo'.

Listing privileges
To list the current user's capabilities, run :

Any command in that does not require a password to be entered, a password will not be required to list the entries either. Otherwise sudo will ask for a password if it isn't remembered.

Prolonging password timeout
By default, if a user has entered their password to authenticate their self to, it is remembered for 5 minutes. If the user wants to prolong this period, he can run to reset the time stamp so that it will take another 5 minutes before  asks for the password again.

The inverse is to kill the time stamp using.