man/less-variables.xml

   1 <?xml version="1.0"?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refsect1>
   7   <title>Environment</title>
   8
   9   <variablelist class='environment-variables'>
  10     <varlistentry id='pager'>
  11       <term><varname>$SYSTEMD_PAGER</varname></term>
  12
  13       <listitem><para>Pager to use when <option>--no-pager</option> is not given; overrides
  14       <varname>$PAGER</varname>. If neither <varname>$SYSTEMD_PAGER</varname> nor <varname>$PAGER</varname> are set, a
  15       set of well-known pager implementations are tried in turn, including
  16       <citerefentry project='man-pages'><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry> and
  17       <citerefentry project='man-pages'><refentrytitle>more</refentrytitle><manvolnum>1</manvolnum></citerefentry>, until one is found. If
  18       no pager implementation is discovered no pager is invoked. Setting this environment variable to an empty string
  19       or the value <literal>cat</literal> is equivalent to passing <option>--no-pager</option>.</para></listitem>
  20     </varlistentry>
  21
  22     <varlistentry id='less'>
  23       <term><varname>$SYSTEMD_LESS</varname></term>
  24
  25       <listitem><para>Override the options passed to <command>less</command> (by default
  26       <literal>FRSXMK</literal>).</para>
  27
  28       <para>Users might want to change two options in particular:</para>
  29
  30       <variablelist>
  31         <varlistentry>
  32           <term><option>K</option></term>
  33
  34           <para>This option instructs the pager to exit immediately when
  35           <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo> is pressed. To allow
  36           <command>less</command> to handle <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo>
  37           itself to switch back to the pager command prompt, unset this option.</para>
  38
  39           <para>If the value of <varname>$SYSTEMD_LESS</varname> does not include <literal>K</literal>,
  40           and the pager that is invoked is <command>less</command>,
  41           <keycombo><keycap>Ctrl</keycap><keycap>C</keycap></keycombo> will be ignored by the
  42           executable, and needs to be handled by the pager.</para>
  43         </varlistentry>
  44
  45         <varlistentry>
  46           <term><option>X</option></term>
  47
  48           <para>This option instructs the pager to not send termcap initialization and deinitialization
  49           strings to the terminal. It is set by default to allow command output to remain visible in the
  50           terminal even after the pager exits. Nevertheless, this prevents some pager functionality from
  51           working, in particular paged output cannot be scrolled with the mouse.</para>
  52         </varlistentry>
  53       </variablelist>
  54
  55       <para>See
  56       <citerefentry project='man-pages'><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  57       for more discussion.</para></listitem>
  58     </varlistentry>
  59
  60     <varlistentry id='lesscharset'>
  61       <term><varname>$SYSTEMD_LESSCHARSET</varname></term>
  62
  63       <listitem><para>Override the charset passed to <command>less</command> (by default <literal>utf-8</literal>, if
  64       the invoking terminal is determined to be UTF-8 compatible).</para></listitem>
  65     </varlistentry>
  66
  67     <varlistentry id='colors'>
  68       <term><varname>$SYSTEMD_COLORS</varname></term>
  69
  70       <listitem><para>The value must be a boolean. Controls whether colorized output should be
  71       generated. This can be specified to override the decision that <command>systemd</command> makes based
  72       on <varname>$TERM</varname> and what the console is connected to.</para>
  73       </listitem>
  74     </varlistentry>
  75
  76     <!-- This is not documented on purpose, because it is not clear if $NO_COLOR will become supported
  77          widely enough. So let's provide support, but without advertising this.
  78     <varlistentry id='no-color'>
  79       <term><varname>$NO_COLOR</varname></term>
  80
  81       <listitem><para>If set (to any value), and <varname>$SYSTEMD_COLORS</varname> is not set, equivalent to
  82       <option>SYSTEMD_COLORS=0</option>. See <ulink url="https://no-color.org/">no-color.org</ulink>.</para>
  83       </listitem>
  84     </varlistentry>
  85     -->
  86
  87     <varlistentry id='urlify'>
  88       <term><varname>$SYSTEMD_URLIFY</varname></term>
  89
  90       <listitem><para>The value must be a boolean. Controls whether clickable links should be generated in
  91       the output for terminal emulators supporting this. This can be specified to override the decision that
  92       <command>systemd</command> makes based on <varname>$TERM</varname> and other conditions.</para>
  93       </listitem>
  94     </varlistentry>
  95
  96   </variablelist>
  97 </refsect1>