source: chapter06/coreutils.xml@ fa21b3d

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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../general.ent">
  %general-entities;
]>
<sect1 id="ch-system-coreutils" role="wrap">
<title>Coreutils-&coreutils-version;</title>
<?dbhtml filename="coreutils.html"?>

<indexterm zone="ch-system-coreutils"><primary sortas="a-Coreutils">Coreutils</primary></indexterm>

<sect2 role="package"><title/>
<para>The Coreutils package contains utilities for showing and setting the
basic system characteristics.</para>

<segmentedlist>
<segtitle>&buildtime;</segtitle>
<segtitle>&diskspace;</segtitle>
<seglistitem><seg>0.9 SBU</seg><seg>52.8 MB</seg></seglistitem>
</segmentedlist>

<segmentedlist>
<segtitle>&dependencies;</segtitle>
<seglistitem><seg>Bash, Binutils, Coreutils, Diffutils, GCC,
Gettext, Glibc, Grep, Make, Perl, and Sed</seg></seglistitem>
</segmentedlist>
</sect2>

<sect2 role="installation">
<title>Installation of Coreutils</title>

<para>A known issue with the <command>uname</command> program from
this package is that the <parameter>-p</parameter> switch always
returns <computeroutput>unknown</computeroutput>. The following patch
fixes this behavior for Intel architectures:</para>

<screen><userinput>patch -Np1 -i ../&coreutils-uname-patch;</userinput></screen>

<para>Prevent Coreutils from installing binaries that will be installed by
other packages later:</para>

<screen><userinput>patch -Np1 -i ../&coreutils-suppress-patch;</userinput></screen>

<para>POSIX requires that programs from Coreutils recognize character
boundaries correctly even in multibyte locales. The following patch
fixes this non-compliance and other internationalization-related bugs:</para>

<screen><userinput>patch -Np1 -i ../&coreutils-i18n-patch;</userinput></screen>

<para>In order for the tests added by this patch to pass, the permissions for
the test file have to be changed:</para>

<screen><userinput>chmod +x tests/sort/sort-mb-tests</userinput></screen>

<note><para>In the past, many bugs were found in this patch. When reporting
new bugs to Coreutils maintainers, please check first if they are reproducible
without this patch.</para></note>

<para>It has been found that translated messages sometimes overflow a buffer
in the <command>who -Hu</command> command. Increase the buffer size:</para>

<screen><userinput>sed -i 's/_LEN 6/_LEN 20/' src/who.c</userinput></screen>

<para>Now prepare Coreutils for compilation:</para>

<screen><userinput>./configure --prefix=/usr</userinput></screen>

<para>Compile the package:</para>

<screen><userinput>make</userinput></screen>

<para>The test suite of Coreutils makes several assumptions about the presence
of system users and groups that are not valid within the minimal environment
that exists at the moment. Therefore, additional items need to be set up before
running the tests. Skip down to <quote>Install the package</quote> if not
running the test suite.</para>

<para>Create two dummy groups and a dummy user:</para>

<screen><userinput>echo "dummy1:x:1000:" &gt;&gt; /etc/group
echo "dummy2:x:1001:dummy" &gt;&gt; /etc/group
echo "dummy:x:1000:1000::/root:/bin/bash" &gt;&gt; /etc/passwd</userinput></screen>

<para>Now the test suite is ready to be run. First, run the tests that
are meant to be run as user <emphasis>root</emphasis>:</para>

<screen><userinput>make NON_ROOT_USERNAME=dummy check-root</userinput></screen>

<para>Then run the remainder of the tests as the
<emphasis>dummy</emphasis> user:</para>

<screen><userinput>src/su dummy -c "make RUN_EXPENSIVE_TESTS=yes check"</userinput></screen>

<para>When testing is complete, remove the dummy user and
groups:</para>

<screen><userinput>sed -i '/dummy/d' /etc/passwd /etc/group</userinput></screen>

<para>Install the package:</para>

<screen><userinput>make install</userinput></screen>

<para>Move programs to the locations specified by the FHS:</para>

<screen><userinput>mv -v /usr/bin/{cat,chgrp,chmod,chown,cp,date,dd,df,echo} /bin
mv -v /usr/bin/{false,hostname,ln,ls,mkdir,mknod,mv,pwd,rm} /bin
mv -v /usr/bin/{rmdir,stty,sync,true,uname} /bin
mv -v /usr/bin/chroot /usr/sbin</userinput></screen>

<para>Some of the scripts in the LFS-Bootscripts package depend on
<command>head</command> and <command>sleep</command>.  As
<filename class="directory">/usr</filename> may not be available during the
early stages of booting, those binaries need to be on the root partition:</para>

<screen><userinput>mv -v /usr/bin/{head,sleep} /bin</userinput></screen>

</sect2>


<sect2 id="contents-coreutils" role="content"><title>Contents of Coreutils</title>

<segmentedlist>
<segtitle>Installed programs</segtitle>
<seglistitem><seg>basename, cat, chgrp, chmod, chown, chroot, cksum,
comm, cp, csplit, cut, date, dd, df, dir, dircolors, dirname, du,
echo, env, expand, expr, factor, false, fmt, fold, groups, head,
hostid, hostname, id, install, join, link, ln, logname, ls, md5sum,
mkdir, mkfifo, mknod, mv, nice, nl, nohup, od, paste, pathchk, pinky,
pr, printenv, printf, ptx, pwd, readlink, rm, rmdir, seq, sha1sum,
shred, sleep, sort, split, stat, stty, sum, sync, tac, tail, tee,
test, touch, tr, true, tsort, tty, uname, unexpand, uniq, unlink,
users, vdir, wc, who, whoami, and yes</seg></seglistitem>
</segmentedlist>

<variablelist><bridgehead renderas="sect3">Short Descriptions</bridgehead>
<?dbfo list-presentation="list"?>
<?dbhtml list-presentation="table"?>

<varlistentry id="basename">
<term><command>basename</command></term>
<listitem>
<para>Strips any path and a given suffix from a file name</para>
<indexterm zone="ch-system-coreutils basename"><primary sortas="b-basename">basename</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="cat">
<term><command>cat</command></term>
<listitem>
<para>Concatenates files to standard output</para>
<indexterm zone="ch-system-coreutils cat"><primary sortas="b-cat">cat</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="chgrp">
<term><command>chgrp</command></term>
<listitem>
<para>Changes the group ownership of files and directories</para>
<indexterm zone="ch-system-coreutils chgrp"><primary sortas="b-chgrp">chgrp</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="chmod">
<term><command>chmod</command></term>
<listitem>
<para>Changes the permissions of each file to the given mode; the mode
can be either a symbolic representation of the changes to make or an
octal number representing the new permissions</para>
<indexterm zone="ch-system-coreutils chmod"><primary sortas="b-chmod">chmod</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="chown">
<term><command>chown</command></term>
<listitem>
<para>Changes the user and/or group ownership of files and directories</para>
<indexterm zone="ch-system-coreutils chown"><primary sortas="b-chown">chown</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="chroot">
<term><command>chroot</command></term>
<listitem>
<para>Runs a command with the specified directory as the 
<filename class="directory">/</filename> directory</para>
<indexterm zone="ch-system-coreutils chroot"><primary sortas="b-chroot">chroot</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="cksum">
<term><command>cksum</command></term>
<listitem>
<para>Prints the Cyclic Redundancy Check (CRC) checksum and the byte
counts of each specified file</para>
<indexterm zone="ch-system-coreutils cksum"><primary sortas="b-cksum">cksum</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="comm">
<term><command>comm</command></term>
<listitem>
<para>Compares two sorted files, outputting in three columns the lines
that are unique and the lines that are common</para>
<indexterm zone="ch-system-coreutils comm"><primary sortas="b-comm">comm</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="cp">
<term><command>cp</command></term>
<listitem>
<para>Copies files</para>
<indexterm zone="ch-system-coreutils cp"><primary sortas="b-cp">cp</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="csplit">
<term><command>csplit</command></term>
<listitem>
<para>Splits a given file into several new files, separating them
according to given patterns or line numbers and outputting the byte
count of each new file</para>
<indexterm zone="ch-system-coreutils csplit"><primary sortas="b-csplit">csplit</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="cut">
<term><command>cut</command></term>
<listitem>
<para>Prints sections of lines, selecting the parts according to given
fields or positions</para>
<indexterm zone="ch-system-coreutils cut"><primary sortas="b-cut">cut</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="date">
<term><command>date</command></term>
<listitem>
<para>Displays the current time in the given format, or sets the
system date</para>
<indexterm zone="ch-system-coreutils date"><primary sortas="b-date">date</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="dd">
<term><command>dd</command> </term>
<listitem>
<para>Copies a file using the given block size and count, while
optionally performing conversions on it</para>
<indexterm zone="ch-system-coreutils dd"><primary sortas="b-dd">dd</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="df">
<term><command>df</command></term>
<listitem>
<para>Reports the amount of disk space available (and used) on all
mounted file systems, or only on the file systems holding the selected
files</para>
<indexterm zone="ch-system-coreutils df"><primary sortas="b-df">df</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="dir">
<term><command>dir</command></term>
<listitem>
<para>Lists the contents of each given directory (the same as
the <command>ls</command> command)</para>
<indexterm zone="ch-system-coreutils dir"><primary sortas="b-dir">dir</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="dircolors">
<term><command>dircolors</command></term>
<listitem>
<para>Outputs commands to set the <envar>LS_COLOR</envar>
environment variable to change the color scheme used by
<command>ls</command></para>
<indexterm zone="ch-system-coreutils dircolors"><primary sortas="b-dircolors">dircolors</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="dirname">
<term><command>dirname</command></term>
<listitem>
<para>Strips the non-directory suffix from a file name</para>
<indexterm zone="ch-system-coreutils dirname"><primary sortas="b-dirname">dirname</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="du">
<term><command>du</command></term>
<listitem>
<para>Reports the amount of disk space used by the current directory,
by each of the given directories (including all subdirectories) or by
each of the given files</para>
<indexterm zone="ch-system-coreutils du"><primary sortas="b-du">du</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="echo">
<term><command>echo</command></term>
<listitem>
<para>Displays the given strings</para>
<indexterm zone="ch-system-coreutils echo"><primary sortas="b-echo">echo</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="env">
<term><command>env</command></term>
<listitem>
<para>Runs a command in a modified environment</para>
<indexterm zone="ch-system-coreutils env"><primary sortas="b-env">env</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="expand">
<term><command>expand</command></term>
<listitem>
<para>Converts tabs to spaces</para>
<indexterm zone="ch-system-coreutils expand"><primary sortas="b-expand">expand</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="expr">
<term><command>expr</command></term>
<listitem>
<para>Evaluates expressions</para>
<indexterm zone="ch-system-coreutils expr"><primary sortas="b-expr">expr</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="factor">
<term><command>factor</command></term>
<listitem>
<para>Prints the prime factors of all specified integer numbers</para>
<indexterm zone="ch-system-coreutils factor"><primary sortas="b-factor">factor</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="false">
<term><command>false</command></term>
<listitem>
<para>Does nothing, unsuccessfully; it always exits with a status code
indicating failure</para>
<indexterm zone="ch-system-coreutils false"><primary sortas="b-false">false</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="fmt">
<term><command>fmt</command></term>
<listitem>
<para>Reformats the paragraphs in the given files</para>
<indexterm zone="ch-system-coreutils fmt"><primary sortas="b-fmt">fmt</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="fold">
<term><command>fold</command></term>
<listitem>
<para>Wraps the lines in the given files</para>
<indexterm zone="ch-system-coreutils fold"><primary sortas="b-fold">fold</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="groups">
<term><command>groups</command></term>
<listitem>
<para>Reports a user's group memberships</para>
<indexterm zone="ch-system-coreutils groups"><primary sortas="b-groups">groups</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="head">
<term><command>head</command></term>
<listitem>
<para>Prints the first ten lines (or the given number of lines) of each given file</para>
<indexterm zone="ch-system-coreutils head"><primary sortas="b-head">head</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hostid">
<term><command>hostid</command></term>
<listitem>
<para>Reports the numeric identifier (in hexadecimal) of the host</para>
<indexterm zone="ch-system-coreutils hostid"><primary sortas="b-hostid">hostid</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hostname">
<term><command>hostname</command></term>
<listitem>
<para>Reports or sets the name of the host</para>
<indexterm zone="ch-system-coreutils hostname"><primary sortas="b-hostname">hostname</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="id">
<term><command>id</command></term>
<listitem>
<para>Reports the effective user ID, group ID, and
group memberships of the current user or specified user</para>
<indexterm zone="ch-system-coreutils id"><primary sortas="b-id">id</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="install">
<term><command>install</command> </term>
<listitem>
<para>Copies files while setting their
permission modes and, if possible, their owner and group</para>
<indexterm zone="ch-system-coreutils install"><primary sortas="b-install">install</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="join">
<term><command>join</command></term>
<listitem>
<para>Joins the lines that have identical join fields from two
separate files</para>
<indexterm zone="ch-system-coreutils join"><primary sortas="b-join">join</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="link">
<term><command>link</command></term>
<listitem>
<para>Creates a hard link with the given name to a file</para>
<indexterm zone="ch-system-coreutils link"><primary sortas="b-link">link</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="ln">
<term><command>ln</command></term>
<listitem>
<para>Makes hard links or soft (symbolic) links between files</para>
<indexterm zone="ch-system-coreutils ln"><primary sortas="b-ln">ln</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="logname">
<term><command>logname</command></term>
<listitem>
<para>Reports the current user's login name</para>
<indexterm zone="ch-system-coreutils logname"><primary sortas="b-logname">logname</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="ls">
<term><command>ls</command></term>
<listitem>
<para>Lists the contents of each given directory</para>
<indexterm zone="ch-system-coreutils ls"><primary sortas="b-ls">ls</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="md5sum">
<term><command>md5sum</command></term>
<listitem>
<para>Reports or checks Message Digest 5 (MD5) checksums</para>
<indexterm zone="ch-system-coreutils md5sum"><primary sortas="b-md5sum">md5sum</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="mkdir">
<term><command>mkdir</command></term>
<listitem>
<para>Creates directories with the given names</para>
<indexterm zone="ch-system-coreutils mkdir"><primary sortas="b-mkdir">mkdir</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="mkfifo">
<term><command>mkfifo</command></term>
<listitem>
<para>Creates First-In, First-Outs (FIFOs), a <quote>named
pipe</quote> in UNIX parlance, with the given names</para>
<indexterm zone="ch-system-coreutils mkfifo"><primary sortas="b-mkfifo">mkfifo</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="mknod">
<term><command>mknod</command></term>
<listitem>
<para>Creates device nodes with the given names; a device node is a
character special file, a block special file, or a FIFO</para>
<indexterm zone="ch-system-coreutils mknod"><primary sortas="b-mknod">mknod</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="mv">
<term><command>mv</command></term>
<listitem>
<para>Moves or renames files or directories</para>
<indexterm zone="ch-system-coreutils mv"><primary sortas="b-mv">mv</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="nice">
<term><command>nice</command></term>
<listitem>
<para>Runs a program with modified scheduling priority</para>
<indexterm zone="ch-system-coreutils nice"><primary sortas="b-nice">nice</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="nl">
<term><command>nl</command></term>
<listitem>
<para>Numbers the lines from the given files</para>
<indexterm zone="ch-system-coreutils nl"><primary sortas="b-nl">nl</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="nohup">
<term><command>nohup</command></term>
<listitem>
<para>Runs a command immune to hangups, with its output redirected to
a log file</para>
<indexterm zone="ch-system-coreutils nohup"><primary sortas="b-nohup">nohup</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="od">
<term><command>od</command></term>
<listitem>
<para>Dumps files in octal and other formats</para>
<indexterm zone="ch-system-coreutils od"><primary sortas="b-od">od</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="paste">
<term><command>paste</command></term>
<listitem>
<para>Merges the given files, joining sequentially corresponding lines
side by side, separated by tab characters</para>
<indexterm zone="ch-system-coreutils paste"><primary sortas="b-paste">paste</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="pathchk">
<term><command>pathchk</command></term>
<listitem>
<para>Checks if file names are valid or portable</para>
<indexterm zone="ch-system-coreutils pathchk"><primary sortas="b-pathchk">pathchk</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="pinky">
<term><command>pinky</command></term>
<listitem>
<para>Is a lightweight finger client; it reports some information about the given users</para>
<indexterm zone="ch-system-coreutils pinky"><primary sortas="b-pinky">pinky</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="pr">
<term><command>pr</command></term>
<listitem>
<para>Paginates and columnates files for printing</para>
<indexterm zone="ch-system-coreutils pr"><primary sortas="b-pr">pr</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="printenv">
<term><command>printenv</command></term>
<listitem>
<para>Prints the environment</para>
<indexterm zone="ch-system-coreutils printenv"><primary sortas="b-printenv">printenv</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="printf">
<term><command>printf</command></term>
<listitem>
<para>Prints the given arguments according to the given format, much
like the C printf function</para>
<indexterm zone="ch-system-coreutils printf"><primary sortas="b-printf">printf</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="ptx">
<term><command>ptx</command></term>
<listitem>
<para>Produces a permuted index from the contents of the given files,
with each keyword in its context</para>
<indexterm zone="ch-system-coreutils ptx"><primary sortas="b-ptx">ptx</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="pwd">
<term><command>pwd</command></term>
<listitem>
<para>Reports the name of the current working directory</para>
<indexterm zone="ch-system-coreutils pwd"><primary sortas="b-pwd">pwd</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="readlink">
<term><command>readlink</command></term>
<listitem>
<para>Reports the value of the given symbolic link</para>
<indexterm zone="ch-system-coreutils readlink"><primary sortas="b-readlink">readlink</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="rm">
<term><command>rm</command></term>
<listitem>
<para>Removes files or directories</para>
<indexterm zone="ch-system-coreutils rm"><primary sortas="b-rm">rm</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="rmdir">
<term><command>rmdir</command></term>
<listitem>
<para>Removes directories if they are empty</para>
<indexterm zone="ch-system-coreutils rmdir"><primary sortas="b-rmdir">rmdir</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="seq">
<term><command>seq</command></term>
<listitem>
<para>Prints a sequence of numbers within a given range and with a
given increment</para>
<indexterm zone="ch-system-coreutils seq"><primary sortas="b-seq">seq</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="sha1sum">
<term><command>sha1sum</command></term>
<listitem>
<para>Prints or checks 160-bit Secure Hash Algorithm 1 (SHA1) checksums</para>
<indexterm zone="ch-system-coreutils sha1sum"><primary sortas="b-sha1sum">sha1sum</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="shred">
<term><command>shred</command></term>
<listitem>
<para>Overwrites the given files repeatedly with complex patterns,
making it difficult to recover the data</para>
<indexterm zone="ch-system-coreutils shred"><primary sortas="b-shred">shred</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="sleep">
<term><command>sleep</command></term>
<listitem>
<para>Pauses for the given amount of time</para>
<indexterm zone="ch-system-coreutils sleep"><primary sortas="b-sleep">sleep</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="sort">
<term><command>sort</command></term>
<listitem>
<para>Sorts the lines from the given files</para>
<indexterm zone="ch-system-coreutils sort"><primary sortas="b-sort">sort</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="split">
<term><command>split</command></term>
<listitem>
<para>Splits the given file into pieces, by size or by number of lines</para>
<indexterm zone="ch-system-coreutils split"><primary sortas="b-split">split</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="stat">
<term><command>stat</command></term>
<listitem>
<para>Displays file or filesystem status</para>
<indexterm zone="ch-system-coreutils stat"><primary sortas="b-stat">stat</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="stty">
<term><command>stty</command></term>
<listitem>
<para>Sets or reports terminal line settings</para>
<indexterm zone="ch-system-coreutils stty"><primary sortas="b-stty">stty</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="sum">
<term><command>sum</command></term>
<listitem>
<para>Prints checksum and block counts for each given file</para>
<indexterm zone="ch-system-coreutils sum"><primary sortas="b-sum">sum</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="sync">
<term><command>sync</command></term>
<listitem>
<para>Flushes file system buffers; it forces changed blocks to disk
and updates the super block</para>
<indexterm zone="ch-system-coreutils sync"><primary sortas="b-sync">sync</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="tac">
<term><command>tac</command></term>
<listitem>
<para>Concatenates the given files in reverse</para>
<indexterm zone="ch-system-coreutils tac"><primary sortas="b-tac">tac</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="tail">
<term><command>tail</command></term>
<listitem>
<para>Prints the last ten lines (or the given number of lines) of each
given file</para>
<indexterm zone="ch-system-coreutils tail"><primary sortas="b-tail">tail</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="tee">
<term><command>tee</command></term>
<listitem>
<para>Reads from standard input while writing both to standard output
and to the given files</para>
<indexterm zone="ch-system-coreutils tee"><primary sortas="b-tee">tee</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="test">
<term><command>test</command></term>
<listitem>
<para>Compares values and checks file types</para>
<indexterm zone="ch-system-coreutils test"><primary sortas="b-test">test</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="touch">
<term><command>touch</command></term>
<listitem>
<para>Changes file timestamps, setting the access and modification
times of the given files to the current time; files that do not exist
are created with zero length</para>
<indexterm zone="ch-system-coreutils touch"><primary sortas="b-touch">touch</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="tr">
<term><command>tr</command></term>
<listitem>
<para>Translates, squeezes, and deletes the given characters from
standard input</para>
<indexterm zone="ch-system-coreutils tr"><primary sortas="b-tr">tr</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="true">
<term><command>true</command></term>
<listitem>
<para>Does nothing, successfully; it always exits with a status code
indicating success</para>
<indexterm zone="ch-system-coreutils true"><primary sortas="b-true">true</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="tsort">
<term><command>tsort</command></term>
<listitem>
<para>Performs a topological sort; it writes a completely ordered list
according to the partial ordering in a given file</para>
<indexterm zone="ch-system-coreutils tsort"><primary sortas="b-tsort">tsort</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="tty">
<term><command>tty</command></term>
<listitem>
<para>Reports the file name of the terminal connected to standard
input</para>
<indexterm zone="ch-system-coreutils tty"><primary sortas="b-tty">tty</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="uname">
<term><command>uname</command></term>
<listitem>
<para>Reports system information</para>
<indexterm zone="ch-system-coreutils uname"><primary sortas="b-uname">uname</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="unexpand">
<term><command>unexpand</command></term>
<listitem>
<para>Converts spaces to tabs</para>
<indexterm zone="ch-system-coreutils unexpand"><primary sortas="b-unexpand">unexpand</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="uniq">
<term><command>uniq</command></term>
<listitem>
<para>Discards all but one of successive identical lines</para>
<indexterm zone="ch-system-coreutils uniq"><primary sortas="b-uniq">uniq</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="unlink">
<term><command>unlink</command></term>
<listitem>
<para>Removes the given file</para>
<indexterm zone="ch-system-coreutils unlink"><primary sortas="b-unlink">unlink</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="users">
<term><command>users</command></term>
<listitem>
<para>Reports the names of the users currently logged on</para>
<indexterm zone="ch-system-coreutils users"><primary sortas="b-users">users</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="vdir">
<term><command>vdir</command></term>
<listitem>
<para>Is the same as <command>ls -l</command></para>
<indexterm zone="ch-system-coreutils vdir"><primary sortas="b-vdir">vdir</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="wc">
<term><command>wc</command></term>
<listitem>
<para>Reports the number of lines, words, and bytes for each given
file, as well as a total line when more than one file is given</para>
<indexterm zone="ch-system-coreutils wc"><primary sortas="b-wc">wc</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="who">
<term><command>who</command></term>
<listitem>
<para>Reports who is logged on</para>
<indexterm zone="ch-system-coreutils who"><primary sortas="b-who">who</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="whoami">
<term><command>whoami</command></term>
<listitem>
<para>Reports the user name associated with the current effective user ID</para>
<indexterm zone="ch-system-coreutils whoami"><primary sortas="b-whoami">whoami</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="yes">
<term><command>yes</command></term>
<listitem>
<para>Repeatedly outputs <quote>y</quote> or a given string until
killed</para>
<indexterm zone="ch-system-coreutils yes"><primary sortas="b-yes">yes</primary></indexterm>
</listitem>
</varlistentry>
</variablelist>

</sect2>

</sect1>