52 lines
2.5 KiB
HTML
52 lines
2.5 KiB
HTML
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<TITLE>Visible bell mini-Howto: Basic Concepts About Termcap and Terminfo</TITLE>
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<H2><A NAME="s5">5. Basic Concepts About Termcap and Terminfo</A></H2>
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<P>The file <CODE>/etc/termcap</CODE> is a text file that lists the
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<CODE>term</CODE>inal <CODE>cap</CODE>abilities. Several applications use the
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<CODE>termcap</CODE> information to move the cursor around the screen and do
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other screen-oriented tasks. <CODE>tcsh</CODE>, <CODE>bash</CODE>, <CODE>vi</CODE> and all
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the <CODE>curses</CODE>-based applications use the <CODE>termcap</CODE> database.
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<P>The database describes several terminal types. The
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<CODE>TERM</CODE> environment variable selects the right behaviour
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at run-time, by naming a <CODE>termcap</CODE> entry to be used by
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applications.
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<P>Within the database, each capability of the terminal appears as a
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two-letter code and a representation of the actual escape sequence
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used to get the desired effect. The separator character between
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different capabilities is the colon (":"). As an example, the audible
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bell, with code "bl", usually appears as "<CODE>bl=^G</CODE>". This sequence
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tells that the bell sound is obtained by printing the control-G
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character, the ASCII BEL.
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<P>In addition to the <CODE>bl</CODE> capability, the <CODE>vb</CODE> capability is
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recognized. It is used to represent the "visible bell". <CODE>vb</CODE> is
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usually missing in the <CODE>linux</CODE> entry of the <CODE>termcap</CODE>
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file.
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<P>Most modern applications and libraries use the <CODE>terminfo</CODE> database
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instead of <CODE>termcap</CODE>. This database uses one file per terminal-type
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and lives in <CODE>/usr/lib/terminfo</CODE>; to avoid using huge
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directories, the description of each terminal type is stored in a
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directory named after its first letter; the <CODE>linux</CODE> entry,
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therefore, is <CODE>/usr/lib/terminfo/l/linux</CODE>. To build a
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<CODE>terminfo</CODE> entry you'll ``compile'' the <CODE>termcap</CODE> description;
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refer to the <CODE>tic</CODE> program and its manual page.
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<P>
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