Date: Sun, 19 May 2013 00:01:58 +0000 (UTC) From: Tom Rhodes <trhodes@FreeBSD.org> To: doc-committers@freebsd.org, svn-doc-projects@freebsd.org Subject: svn commit: r41667 - in projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook: basics users Message-ID: <201305190001.r4J01wQe092105@svn.freebsd.org>
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Author: trhodes Date: Sun May 19 00:01:57 2013 New Revision: 41667 URL: http://svnweb.freebsd.org/changeset/doc/41667 Log: Add more information on binary formats in basics. Add a note about sudo in the users chapter. Add a section on using root in the users chapter. Modified: projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/basics/chapter.xml projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/users/chapter.xml Modified: projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/basics/chapter.xml ============================================================================== --- projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/basics/chapter.xml Sat May 18 23:44:23 2013 (r41666) +++ projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/basics/chapter.xml Sun May 19 00:01:57 2013 (r41667) @@ -302,6 +302,15 @@ console none managing requests for hardware devices, peripherals, memory, and CPU time fairly to each user.</para> + <para>Much more information about User Accounts is in the chapter + about <link linkend="users">accounts</link>. For now you just + need to know that each person (user) who uses the computer should be + given their own username and password. The system keeps track + of the people using the computer based on this username. Since + it is often the case that several people are working on the same + project Unix also provides groups. Several users can be placed + in the same group.</para> + <para>Because the system is capable of supporting multiple users, everything the system manages has a set of permissions governing who can read, write, and execute the resource. These @@ -2416,8 +2425,23 @@ Swap: 256M Total, 38M Used, 217M Free, 1 <sect1 id="binary-formats"> <title>Binary Formats</title> - <para>To understand why &os; uses the &man.elf.5; format,the three - currently <quote>dominant</quote> executable formats for &unix; + <para>Typically when a command is passed to the shell, the shell + will arrange for an executable file to be loaded into memory and + a new process is created. Executable files can either be a binary + file (usually created by the linker as part of compiling a program) + or a shell script (text file to be interpreted by a binary file, + like &man.sh.1; or &man.perl.1;). The &man.file.1; command can + usually determine what is inside a file.</para> + + <para>Binary files need to have a well defined format for the system + to be able to use them properly. Part of the file will be the + executable machine code (the instructions that tell the CPU what + to do), part of it will be data space with pre-defined values, + part will be data space with no pre-defined values, etc. Through + time, different binary file formats have evolved.</para> + + <para>To understand why &os; uses the &man.elf.5; format, the three + currently <quote>dominant</quote>, executable formats for &unix; must be described:</para> <itemizedlist> @@ -2545,6 +2569,14 @@ Swap: 256M Total, 38M Used, 217M Free, 1 out of the <filename>GENERIC</filename> kernel, and eventually removed from the kernel once the need to run legacy <filename>a.out</filename> programs is past.</para> + + <para>In addition to &man.file.1; another command that can prove + useful when working with executables is &man.ldd.1;. If + &man.file.1; reveals that a file is a dynamically linked + executable &man.ldd.1; can figure out what dynamically linked + libraries that executable file requires. Sometimes programs can + be linked against compatibility libraries instead of the main + system libraries, or otherwise rely on dynamic libraries.</para> </sect1> <sect1 id="basics-more-information"> Modified: projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/users/chapter.xml ============================================================================== --- projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/users/chapter.xml Sat May 18 23:44:23 2013 (r41666) +++ projects/ISBN_1-57176-407-0/en_US.ISO8859-1/books/handbook/users/chapter.xml Sun May 19 00:01:57 2013 (r41667) @@ -1034,4 +1034,49 @@ uid=1001(jru) gid=1001(jru) groups=1001( <filename>/etc/group</filename>, refer to &man.pw.8; and &man.group.5;.</para> </sect1> + + <sect1 id="users-becomesuper"> + <title>Becoming Superuser</title> + + <para>There are several ways to do things as the superuser. The + worst way is to log in as <username>root</username> directly. + Usually very little activity requires <username>root</username> + so logging off and logging in as <username>root</username>, + performing tasks, then logging off and on again as a normal user + is a waste of time.</para> + + <para>A better way is to use &man.su.1; without providing a login + but using <literal>-</literal> to inherit the root environment. + Not providing a login will imply super user. For this to work + the login that must be in the <groupname>wheel</groupname> group. + An example of a typical software installation would involve the + administrator unpacking the software as a normal user and then + elevating their privileges for the build and installation of + the software.</para> + + <example> + <title>Install a Program As The Superuser</title> + + <screen>&prompt.user; <userinput>configure</userinput> +&prompt.user; <userinput>make</userinput> +&prompt.user; <userinput>su -</userinput> +Password: +&prompt.root; <userinput>make install</userinput> +&prompt.root; <userinput>exit</userinput> +&prompt.user;</screen> + </example> + + <para>Note in this example the transition to + <username>root</username> is less painful than logging off + and back on twice.</para> + + <para>Using &man.su.1; works well for single systems or small + networks with just one system administrator. For more complex + environments (or even for these simple environments) + <command>sudo</command> should be used. It is provided as a port, + <filename role="package">security/sudo</filename>. It allows for + things like activity logging, granting users the ability to only + run only certain commands as the superuser, and several other + options.</para> + </sect1> </chapter>help
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