termcap.3

操作系统设计与实现源码

.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)termcap.3x	6.1 (Berkeley) 5/15/85
.\"
.TH TERMCAP 3 "May 15, 1985"
.UC 4
.SH NAME
termcap, tgetent, tgetnum, tgetflag, tgetstr, tgoto, tputs \- terminal independent operation routines
.SH SYNOPSIS
.nf
.ft B
#include <termcap.h>

int tgetent(char *\fIbp\fP, char *\fIname\fP)
int tgetflag(char *\fIid\fP)
int tgetnum(char *\fIid\fP)
char *tgetstr(char *\fIid\fP, char **\fIarea\fP)
char *tgoto(char *\fIcm\fP, int \fIdestcol\fP, int \fIdestline\fP)
int tputs(char *\fIcp\fP, int \fIaffcnt\fP, void (*\fIoutc\fP)(int))
.ft R
.fi
.SH DESCRIPTION
These functions extract and use capabilities from the terminal capability data
base
.BR termcap (5).
These are low level routines;
see
.BR curses (3)
for a higher level package.
.PP
.B Tgetent
extracts the entry for terminal
.I name
into the buffer at
.IR bp .
.I Bp
should be a character buffer of size
1024 and must be retained through all subsequent calls
to
.BR tgetnum ,
.BR tgetflag ,
and
.BR tgetstr .
.B Tgetent
returns \-1 if it cannot find a termcap
file, 0 if the terminal name given does not have an entry,
and 1 if all goes well.
.PP
.B Tgetent
uses the following recipe to find the termcap file and entry
.IR name :
.PP
.in +5n
if $TERMCAP is itself a termcap entry for
.I name
.br
then
.in +5n
use $TERMCAP
.in -5n
elif $TERMCAP names a file
.br
then
.in +5n
use entry
.I name
found in that file
.in -5n
elif this is Minix-vmd
.br
then
.in +5n
if $TERMPATH is defined
.br
then
.in +5n
search the termcap files named in $TERMPATH for the first occurance of a
.I name
entry and use that entry
.in -5n
else
.in +5n
the path
.B $HOME/.termcap:/etc/termcap:/usr/etc/termcap"
is searched for entry
.I name
.in -5n
fi
.in -5n
fi
.in -5n
.RE
.PP
.B Tgetnum
gets the numeric value of capability
.IR id ,
returning \-1 if is not given for the terminal.
.B Tgetflag
returns 1 if the specified capability is present in
the terminal's entry, 0 if it is not.
.B Tgetstr
returns the string value of the capability
.IR id ,
places it in the buffer at
.IR area ,
and advances the
.I area
pointer.
It decodes the abbreviations for this field described in
.BR termcap (5),
except for cursor addressing and padding information.
.B Tgetstr
returns NULL if the capability was not found.
.PP
.B Tgoto
returns a cursor addressing string decoded from
.I cm
to go to column
.I destcol
in line
.IR destline .
It uses the external variables
.B UP
(from the \fBup\fR capability)
and
.B BC
(if \fBbc\fR is given rather than \fBbs\fR)
if necessary to avoid placing \fB\en\fR, \fB^D\fR or \fB^@\fR in
the returned string.
(Programs which call tgoto should be sure to turn off the XTABS bit(s),
since
.B tgoto
may now output a tab.
Note that programs using termcap should in general turn off XTABS
anyway since some terminals use CTRL-I for other functions,
such as nondestructive space.)
If a \fB%\fR sequence is given which is not understood, then
.B tgoto
returns \*(lqOOPS\*(rq.
.PP
.B Tputs
decodes the leading padding information of the string
.IR cp ;
.I affcnt
gives the number of lines affected by the operation, or 1 if this is
not applicable,
.I outc
is a routine which is called with each character in turn.
The external variable
.B ospeed
should contain the output speed of the terminal as encoded by
.BR stty (3).
The external variable
.B PC
should contain a pad character to be used (from the \fBpc\fR capability)
if a null (\fB^@\fR) is inappropriate.
.SH SEE ALSO
.BR curses (3),
.BR termcap (5).
.SH AUTHOR
William Joy
.SH NOTES
The Minix implementation does not support any of the external variables,
only the functions calls.  The Minix-vmd termcap does support it all,
although noone in his right mind meddles with those variables.