source: general/sysutils/at.xml@ c4f64d6

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;

  <!ENTITY at-download-http "&sources-anduin-http;/at/at_&at-version;.orig.tar.gz">
  <!ENTITY at-download-ftp  " ">
  <!ENTITY at-md5sum        "ca3657a1c90d7c3d252e0bc17feddc6e">
  <!ENTITY at-size          "130 KB">
  <!ENTITY at-buildsize     "1.9 MB (including tests)">
  <!ENTITY at-time          "less than 0.1 SBU">
]>

<sect1 id="at" xreflabel="At-&at-version;">
  <?dbhtml filename="at.html"?>


  <title>at-&at-version;</title>

  <indexterm zone="at">
    <primary sortas="a-at">at</primary>
  </indexterm>

  <sect2 role="package">
    <title>Introduction to at</title>

    <para>
      The <application>at</application> package provides delayed job execution
      and batch processing. It is required for Linux Standards Base (LSB)
      conformance.
    </para>

    &lfs121_checked;

    <bridgehead renderas="sect3">Package Information</bridgehead>
    <itemizedlist spacing="compact">
      <listitem>
        <para>
          Download (HTTP): <ulink url="&at-download-http;"/>
        </para>
      </listitem>
      <listitem>
        <para>
          Download (FTP): <ulink url="&at-download-ftp;"/>
        </para>
      </listitem>
      <listitem>
        <para>
          Download MD5 sum: &at-md5sum;
        </para>
      </listitem>
      <listitem>
        <para>
          Download size: &at-size;
        </para>
      </listitem>
      <listitem>
        <para>
          Estimated disk space required: &at-buildsize;
        </para>
      </listitem>
      <listitem>
        <para>
          Estimated build time: &at-time;
        </para>
      </listitem>
    </itemizedlist>

    <bridgehead renderas="sect3">at Dependencies</bridgehead>

    <bridgehead renderas="sect4">Required</bridgehead>
    <para role="required">
      An <xref linkend="server-mail"/>
    </para>

    <bridgehead renderas="sect4">Optional</bridgehead>
    <para role="optional">
      <xref linkend="linux-pam"/>
    </para>

  </sect2>

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

    <para>
      Before building <application>at</application>, as the
      <systemitem class="username">root</systemitem> user you should create
      the group and user <systemitem class="username">atd</systemitem> which
      will run the <command>atd</command> daemon:
    </para>

<screen role="root"><userinput>groupadd -g 17 atd                                                  &amp;&amp;
useradd -d /dev/null -c "atd daemon" -g atd -s /bin/false -u 17 atd</userinput></screen>

    <para>
      Install <application>at</application> with the following
      commands:
    </para>

    <screen revision="sysv"><userinput>./configure --with-daemon_username=atd        \
            --with-daemon_groupname=atd       \
            --with-jobdir=/var/spool/atjobs   \
            --with-atspool=/var/spool/atspool \
            SENDMAIL=/usr/sbin/sendmail       &amp;&amp;
make -j1</userinput></screen>

    <screen revision="systemd"><userinput>./configure --with-daemon_username=atd        \
            --with-daemon_groupname=atd       \
            SENDMAIL=/usr/sbin/sendmail       \
            --with-jobdir=/var/spool/atjobs   \
            --with-atspool=/var/spool/atspool \
            --with-systemdsystemunitdir=/lib/systemd/system &amp;&amp;
make -j1</userinput></screen>

    <para>
      To test the results, issue: <command>make test</command>.
    </para>


    <para>
      Now, as the <systemitem class="username">root</systemitem> user:
    </para>

<screen role="root"><userinput>make install docdir=/usr/share/doc/at-&at-version; \
             atdocdir=/usr/share/doc/at-&at-version;</userinput></screen>

  </sect2>

  <sect2 role="configuration">
    <title>Configuring at</title>

    <sect3 id="at-config">
      <title>Config Files</title>

      <para>
        <filename>/etc/at.allow</filename> and
        <filename>/etc/at.deny</filename> determines who can submit jobs via at
        or batch.
      </para>

      <indexterm zone="at at-config">
        <primary sortas="e-etc-at.allow">/etc/at.allow</primary>
      </indexterm>

      <indexterm zone="at at-config">
        <primary sortas="e-etc-at.deny">/etc/at.deny</primary>
      </indexterm>

    </sect3>

    <sect3>
      <title>Linux PAM Configuration</title>

      <para>
        If <application>At</application> has been built with
        <application>Linux PAM</application> support, you need to create a
        <application>PAM</application> configuration file, to get it working
        correctly with BLFS.
      </para>

      <para>
        Issue the following commands as the <systemitem
        class="username">root</systemitem> user to create the configuration
        file for <application>Linux PAM</application>:
      </para>

<screen role="root"><userinput>cat &gt; /etc/pam.d/atd &lt;&lt; "EOF"
<literal># Begin /etc/pam.d/atd

auth     required pam_unix.so
account  required pam_unix.so
password required pam_unix.so
session  required pam_unix.so

# End /etc/pam.d/atd</literal>
EOF</userinput></screen>

    </sect3>

    <sect3  id="at-init">
      <title><phrase revision="sysv">Boot Script</phrase>
             <phrase revision="systemd">Systemd Unit</phrase></title>

      <para revision="sysv">
        Install the <filename>/etc/init.d/atd</filename>
        init script from the <xref linkend="bootscripts"/> package.
      </para>

      <para revision="systemd">
        To start the <command>atd</command> daemon at boot,
        enable the previously installed systemd unit by
        running the following command as the
        <systemitem class="username">root</systemitem> user:
      </para>

      <indexterm zone="at at-init">
        <primary sortas="f-at">at</primary>
      </indexterm>

<screen role="root" revision="sysv"><userinput>make install-atd</userinput></screen>

<screen role="root" revision="systemd"><userinput>systemctl enable atd</userinput></screen>

    </sect3>

  </sect2>

  <sect2 role="content">
    <title>Contents</title>

    <segmentedlist>
      <segtitle>Installed Programs</segtitle>
      <segtitle>Installed Libraries</segtitle>
      <segtitle>Installed Directories</segtitle>

      <seglistitem>
        <seg>
          at, atd, atq (symlink), atrm (symlink), atrun, and batch
        </seg>
        <seg>
          None
        </seg>
        <seg>
          /usr/share/doc/at-&at-version;
        </seg>
      </seglistitem>
    </segmentedlist>

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

      <varlistentry id="at-prog">
        <term><command>at</command></term>
        <listitem>
          <para>
            queues, examines or deletes jobs for later execution
          </para>
          <indexterm zone="at at-prog">
            <primary sortas="b-at">at</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="atd">
        <term><command>atd</command></term>
        <listitem>
          <para>
            is the daemon that runs jobs queued for later execution
          </para>
          <indexterm zone="at atd">
            <primary sortas="b-atd">atd</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="atq">
        <term><command>atq</command></term>
        <listitem>
          <para>
            lists the user's pending jobs, or all jobs, if superuser
          </para>
          <indexterm zone="at atq">
            <primary sortas="b-atq">atq</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="atrm">
        <term><command>atrm</command></term>
        <listitem>
          <para>
            deletes jobs, identified by their job number
          </para>
          <indexterm zone="at atrm">
            <primary sortas="b-atrm">atrm</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="atrun">
        <term><command>atrun</command></term>
        <listitem>
          <para>
            runs jobs queued for later execution
          </para>
          <indexterm zone="at atrun">
            <primary sortas="b-atrun">atrun</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="batch">
        <term><command>batch</command></term>
        <listitem>
          <para>
            is a script that executes commands when system load levels permit
          </para>
          <indexterm zone="at batch">
            <primary sortas="b-batch">batch</primary>
          </indexterm>
        </listitem>
      </varlistentry>

    </variablelist>

  </sect2>

</sect1>