558 lines
12 KiB
Plaintext
558 lines
12 KiB
Plaintext
<!--
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;; $Id: interact.docbook,v 1.1 2012/08/25 07:19:02 gdr Exp $
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-->
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<chapter id="gsh-interact">
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<title>Interacting with the GNO Shell</title>
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<section id="gsh-interact-exec">
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<title>Executing Commands</title>
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<para>A command consists of two parts: a name and
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its arguments. The command name is the name used to start the
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command. The name is usually the name of a file which can be
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executed. The only exceptions are commands which are built-in to
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the shell. These commands are documented in
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<xref linkend="gsh-commands"/>.
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Any shell utility command with a filetype of EXE,
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SYS16, or EXEC, can be executed in this fashion. The command name
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must be separated from the command arguments with a space.</para>
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<para>The command arguments are parameters that
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the command takes as data to work with (In Applesoft BASIC,
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"HELLO WORLD" would be an argument for the <command>PRINT</command>
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command).
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Command arguments are separated from each other with a space.
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Note that although arguments extend the usefulness of a command,
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not all commands have arguments. Any arguments entered after the
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command will be passed by the shell to the program when it starts
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exectuting. </para>
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<para>The examples below use the following
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commands:</para>
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<informalexample>
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<screen>
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qtime displays time in English text
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echo prints arguments to the screen
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</screen>
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</informalexample>
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<para>Examples:</para>
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<informalexample>
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<screen>
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<prompt>% </prompt><userinput>qtime</userinput>
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It's almost five.
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<prompt>% </prompt><userinput>echo II Infinitum</userinput>
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II Infinitum
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</screen>
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</informalexample>
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<para>At the simplest level the user enters
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commands to the shell by typing them on the keyboard. <command>gsh</command>
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includes a command-line editor to help the user enter and edit
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commands. The editor also provides a way to modify and execute
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previous commands. Additionally the editor can help complete the
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names of commands, filenames and variables.</para>
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</section>
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<section>
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<title>Commandline Editing</title>
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<para>The following sections provide a complete description of the
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functions of the command-line editor with short examples
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depicting how each editing key works.</para>
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<para>Throughout the examples the underline character, "_",
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will be used to represent the current cursor
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position. In addition, "OA" is used to represent the
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Open Apple key and the term <parameter>word</parameter> is used to indicate a
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string of characters consisting of only letters, digits, and
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underscores. To the right of a editing key entry is the
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<command>bindkey</command> function name which is used to remap
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editing functions to new keys. This information is included for
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reference purposes only. See <xref linkend="gsh-commands"/> for
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more information on the <command>bindkey</command> command.
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</para>
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<para>It should be pointed out that at this stage
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that the user should not be concerned with what the actual
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commands used in the examples do, rather the user should
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concentrate on how the command-line editor functions work.</para>
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</section>
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<section>
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<title>Command Input</title>
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<para>
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These command-line editor keys
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deal with entering text directly on the command-line.</para>
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<variablelist>
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<varlistentry>
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<term>
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RETURN
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</term>
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<listitem>
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<para>
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Newline.
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</para>
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<para>
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The return key is used to terminate
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line input. <command>gsh</command> then interprets the command on the
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line and acts accordingly. The position of the cursor on the
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command-line does not matter.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-D
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</term>
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<listitem>
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<para>
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(no bindkey name)
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</para>
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<para>
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Causes <command>gsh</command> to exit if it was the first
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character typed on the command-line. If there are still jobs
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running in the background or stopped, <command>gsh</command> will display
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the message "There are stopped jobs". If you press CTRL-D a
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second time without an intervening command, <command>gsh</command> will
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terminate all the jobs in the job list and exit.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-R
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</term>
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<listitem>
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<para>
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redraw
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</para>
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<para>
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Moves to the next line and re-displays
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the current command-line. Use this to redraw the current line
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if the screen becomes garbled.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-L
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</term>
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<listitem>
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<para>
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clear-screen
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</para>
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<para>
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Clears the screen, moves the cursor to
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the top line, and redraws the prompt and any command-line
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that was in the process of being edited.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section>
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<title>Command Editing</title>
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<para>
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These command-line editor keys
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allow editing of the command-line text.
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</para>
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<variablelist>
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<varlistentry>
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<term>
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CTRL-B
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</term>
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<term>
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LEFT-ARROW
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</term>
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<listitem>
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<para>
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backward-char
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</para>
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<para>
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Moves the cursor one character to the left. You
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cannot move past the first character on the line. If so, <command>gsh</command>
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will output an error beep.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-F
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</term>
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<term>
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RIGHT-ARROW
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</term>
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<listitem>
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<para>
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forward-char
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</para>
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<para>
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Moves the cursor one character to the right. You
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cannot move past the last character on the line. If so, <command>gsh</command>
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will output an error beep.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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DELETE
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</term>
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<listitem>
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<para>
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backward-delete-char
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</para>
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<para>
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Deletes the character to the left of the
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cursor. You can delete up to the first character on the
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command-line.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CLEAR
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</term>
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<term>
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CTRL-X
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</term>
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<listitem>
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<para>
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kill-whole-line
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</para>
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<para>
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Deletes all characters on the command line and positions the
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cursor after the prompt.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-Y
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</term>
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<listitem>
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<para>
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kill-end-of-line
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</para>
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<para>
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Deletes all characters from the cursor to
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the end of the command-line.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-D
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</term>
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<term>
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OA-D
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</term>
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<listitem>
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<para>
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delete-char
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</para>
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<para>
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Deletes the character under the cursor.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-A
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</term>
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<term>
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OA-<
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</term>
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<listitem>
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<para>
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beginning-of-line
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</para>
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<para>
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Moves the cursor to the beginning of the line.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-E
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</term>
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<term>
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OA->
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</term>
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<listitem>
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<para>
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end-of-line
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</para>
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<para>
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Moves the cursor to the first position past the last character on
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the line.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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OA-RIGHT-ARROW
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</term>
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<listitem>
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<para>
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forward-word
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</para>
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<para>
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Moves the cursor right to the last
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character of the current word.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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OA-LEFT-ARROW
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</term>
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<listitem>
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<para>
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backward-word
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</para>
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<para>
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Moves the cursor left to the beginning of
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the current word.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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OA-E
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</term>
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<listitem>
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<para>
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toggle-cursor
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</para>
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<para>
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Toggles input mode between insert and
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overstrike. Overstrike mode is distinguished by a solid inverse
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cursor and insert mode by a blinking '_' (underscore) cursor. In
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overstrike mode, any characters that are typed directly
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over-write those characters below the cursor. In insert mode, the
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characters typed are inserted before the character below the
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cursor.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section id="gsh-interact-hist">
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<title>History Editing</title>
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<para>
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These command-line editor keys allow access
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to previously entered commands. The GNO shell automatically keeps
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track of previous commands in what is called a history buffer.
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</para>
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<para>
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The maximum number of command-lines saved
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in the history buffer is determined by the shell variable . A
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default value for this variable is set in the <filename>gshrc</filename> file
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that the GNO Installer creates. The lines saved to the history
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buffer are kept between sessions. That is, when you exit
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<command>gsh</command>, $SAVEHIST command-lines are saved to your
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<filename>$HOME/history</filename> file.
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When <command>gsh</command> is invoked again, all
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command-lines saved in the history buffer will be available using
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history editing keys. See <xref linkend="gsh-shellvars-predef"/>
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for more information on the HISTORY and SAVEHIST shell variables.
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</para>
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<variablelist>
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<varlistentry>
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<term>
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CTRL-P
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</term>
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<term>
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UP-ARROW
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</term>
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<listitem>
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<para>
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up-history
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</para>
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<para>
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Fetches the previous command-line. If the current
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command-line is the first line in the history buffer, the
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next line fetched will be an empty command-line. If
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invoked again, the last line in the history buffer will
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be displayed.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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CTRL-N
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</term>
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<term>
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DOWN-ARROW
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</term>
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<listitem>
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<para>
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down-history
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</para>
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<para>
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Fetches the next command-line. If the
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current command-line is the last command line in the
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history buffer, the next line fetched will be the first
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command-line in the history buffer.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section>
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<title>Command, Filename, and Variable Completion</title>
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<para>
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These command-line editor keys can
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be used to complete filenames, commands and variables.
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</para>
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<variablelist>
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<varlistentry>
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<term>
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CTRL-D
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</term>
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<listitem>
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<para>
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list-choices
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</para>
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<para>
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Lists commands and pathnames that match the current word.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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TAB
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</term>
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<listitem>
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<para>
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complete-word
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</para>
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<para>
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Command, pathname and variable
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completion. If the cursor is positioned on the first word
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of the command-line, command pathname is performed, else
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pathname or variable completion is performed. The word is
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expanded to the closest matching command, pathname or
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variable. Characters are appended up to the point that
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they would cause more than one. If a complete pathname
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results for pathname completion, <command>gsh</command> appends a "/"
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if the pathname is a directory; otherwise, it appends a space.
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</para>
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<para>
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Note that if there is more than one
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match for the partial command, <command>gsh</command> will sound a
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beep on the speaker. You can use the CTRL-D (list-choices)
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command to see the list of possible
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matches, and should either finish entering the command
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manually or type enough additional characters to
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guarantee a unique match.
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</para>
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<para>
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If the FIGNORE environment variable
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is set, <command>gsh</command> ignores filenames (when doing
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completion) that end with any of the suffixes in $FIGNORE.
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See <xref linkend="gsh-shellvars-predef"/>
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for more information regarding the FIGNORE environment variable.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section>
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<title>Other Ways of Entering Commands</title>
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<section>
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<title>Terminal Input</title>
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<para>
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An example involving the connection of a
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terminal will be shown in
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<xref linkend="gsh-productive-redirect"/>
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but it is necessary to mention here that when
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using <command>gsh</command> over a terminal, some keystrokes must be
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slightly modified. This is because there are no terminals that
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can transmit the OA key. Instead, a two-key sequence must be used
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which replaces OA with ESC. For example, instead of pressing OA-E
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to toggle insert mode, you can type ESC-E over a terminal to do
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the same thing.
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</para>
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<para>
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If you will be using terminals seriously
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then you should install the Remote Access package.
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</para>
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</section>
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<section>
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<title>Script File</title>
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<para>
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While you would normally type commands on
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the command-line, you can also store a series of often used
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commands in a file. A file containing such a series of commands
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is called a script. A script is normally created by using a text
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editor.
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</para>
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<para>
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By typing the name of the script file, the
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shell will execute it, line by line, as if you had typed each
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command separately. The <filename>gshrc</filename> file presented in
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<xref linkend="gsh-start-custom"/>
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is an example of a script file.
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</para>
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</section>
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</section>
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</chapter>
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