Rdb: Ruby-Nachbau der MWC /rdb-Werkzeuge

man/cursor.man

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+.TH cursor "" "" "/rdb Command"
+.PC "Move the cursor to the row and column requested"
+\fBcursor \fIrow col \fB[ \fICURSOR \fB]\fR
+.PP
+.II cursor^move
+.II "move cursor"
+.II "reposition cursor"
+The command
+.B cursor
+move the cursor to screen position
+.I row
+and
+.IR column .
+You can
+.B cursor
+and the
+.B /rdb
+command
+.B clear.rdb
+to perform complex screen handling from within a shell script.
+You can paint your screen with cursor moves and
+.B echo
+commands;
+then use the
+.B read
+command to read the user's input; and finally use various
+COHERENT and
+.B /rdb
+commands to examine and confirm the input.
+You can also clear fields of the screen by moving the cursor
+and writing blanks.
+.PP
+You must give the row and column you want.
+.B cursor
+also needs the cursor movement (\fBcm\fR) entry from file
+.BR /etc/termcap .
+This can be given as an argument, but the easiest way
+is to set up the shell variable called
+.B CURSOR ;
+then
+.B cursor
+will find it in its environment automatically.
+To set up the
+.B CURSOR
+variable, do the following:
+.DM
+	CURSOR=`termput cm`
+.DE
+.PP
+.\"On UNIX System 5 Release 2, use
+.\".B tput:
+.\".sp
+.\".nf
+.\"$ CURSOR=`tput cup`
+.\".fi
+.\".sp
+Another way is to use your text editor to find the entry in
+.B /etc/termcap
+and copy its
+.B cm
+entry for your terminal to your
+.BR .profile :
+.DM
+	CURSOR=^[[%p1%d;%p2%dH
+.DE
+.PP
+This is the entry for the
+.B pc
+terminal.
+The uparrow bracket (^[) is the ESC character (\fB<ctrl-[>\fR).
+The function
+.I tgoto
+function from the
+.B termcap
+library
+converts it into the proper escape string.
+.SH Example
+The following moves the cursor to the middle of an 80-by-24 screen:
+.DM
+	cursor 11 38
+.DE
+.SH Speed
+.B cursor
+is fast, but there is a much faster way.
+Set a shell variable like
+.B L22
+to move to the 22nd line:
+.DM
+	L22=`cursor 23 0`
+.DE
+.PP
+Then you can use:
+.DM
+	echo "$L22$MESSAGE\ec"
+.DE
+.PP
+in your shell programs for a fast cursor movement and to print a message.
+Note the quotation marks around the messages in case there are
+special characters.
+Also note the
+.IR \ec ,
+which tells
+.B echo
+not to print a carriage return.
+.\"In older versions of UNIX
+.\"it is
+.\".I -n
+.\"instead of
+.\".I \ec.
+.PP
+An even better trick is to use the shell feature that tests
+to see if a variable has been set and only gives it a value
+when it needs one:
+.DM
+	echo "${L22:=`cursor 22 0`}$MESSAGE\ec"
+.DE
+.PP
+All of this magic causes the shell to check if
+.B L22
+has a value.
+If not, it executes the
+.B cursor
+command and assigns the value to
+.B L22.
+Then, if this line is called in a loop, the next time the
+value will have been set and will be about 20 times faster.
+.SH "See Also"
+.B
+termput
+.R
+.br
+COHERENT Lexicon:
+.B
+\&.profile,
+termcap
+.R