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94 lines
2.7 KiB
Plaintext
94 lines
2.7 KiB
Plaintext
NAME
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prompt - display a prompt and wait for input from terminal
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SYNOPSIS
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prompt(str)
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TYPES
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str string
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return string
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DESCRIPTION
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When prompt(str) is called and input is from a terminal, the string
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str is displayed and execution is halted until a newline ends a line
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read from the input; the string formed by the characters in the line
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(other than the newline) is returned as the value of prompt().
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Be careful when using prompt(str) while calc is being used as a
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shell script. Unless calc is run with the -p command line option,
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the prompt builtin will fail and return null. This is because when
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calc is running as a shell script, calc will close stdin run in in
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a non-interactive mode.
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The following shell script will always print "got null" because
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stdin will be closed by calc during startup:
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#!/usr/bin/calc -q -f
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# The prompt will ALWAYS FAIL and return a null value
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n = prompt("Test> ");
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if (isnull(n)) {
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print("got null");
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} else {
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print("got " + n);
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}
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However the following shell script (note the -p before the -f in
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the 1st line) will be interactive, prompt with "Test> " and print
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the "got" result as expected:
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#!/usr/bin/calc -q -p -f
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n = prompt("Test> ");
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if (isnull(n)) {
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print("got null");
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} else {
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print("got " + n);
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}
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EXAMPLE
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; x = prompt("? ");
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? 273
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; x
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"273"
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; for (;;) {s = prompt("? "); if (s=="end") break; print "\t":eval(s)^2;}
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? 3
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9
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? 2 + 3
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25
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? end
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LIMITS
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none
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LINK LIBRARY
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none
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SEE ALSO
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command, fgetfield, fgetline, fgetstr, unexpected
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## Copyright (C) 1999,2006,2023 Landon Curt Noll
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##
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## Calc is open software; you can redistribute it and/or modify it under
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## the terms of the version 2.1 of the GNU Lesser General Public License
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## as published by the Free Software Foundation.
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##
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## Public License for more details.
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##
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## A copy of version 2.1 of the GNU Lesser General Public License is
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## distributed with calc under the filename COPYING-LGPL. You should have
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## received a copy with calc; if not, write to Free Software Foundation, Inc.
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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##
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## Under source code control: 1995/12/18 12:34:58
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## File existed as early as: 1995
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##
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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