Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!mailrus!cornell!uw-beaver!ssc-vax!uvicctr!tholm
From: tholm@uvicctr.UUCP (Terrence W. Holm)
Newsgroups: comp.os.minix
Subject: getopt(3)
Message-ID: <532@uvicctr.UUCP>
Date: 31 Oct 88 16:37:16 GMT
Reply-To: tholm@uvicctr.UUCP (Terrence W. Holm)
Organization: University of Victoria, Victoria B.C. Canada
Lines: 170

EFTH MINIX report #54  - November 1988 -  getopt(3)


The recently posted ps(1) requires getopt(3), for those
people missing this subroutine: Here is Henry Spencer's
version, (slightly locally modified).

----------------------------------------------------------
echo x - getopt.c
gres '^X' '' > getopt.c << '/'
X/*
X * getopt - get option letter from argv
X *
X * Copyright (c) Henry Spencer.
X * Written by Henry Spencer.
X *
X * This software is not subject to any license of the American Telephone
X * and Telegraph Company or of the Regents of the University of California.
X *
X * Permission is granted to anyone to use this software for any purpose on
X * any computer system, and to alter it and redistribute it freely, subject
X * to the following restrictions:
X *
X * 1. The author is not responsible for the consequences of use of this
X *    software, no matter how awful, even if they arise from flaws in it.
X *
X * 2. The origin of this software must not be misrepresented, either by
X *    explicit claim or by omission.  Since few users ever read sources,
X *    credits must appear in the documentation.
X *
X * 3. Altered versions must be plainly marked as such, and must not be
X *    misrepresented as being the original software.  Since few users
X *    ever read sources, credits must appear in the documentation.
X *
X * 4. This notice may not be removed or altered.
X */
X
X/*
X * changed index() calls to strchr() - darwin, oct 87.
X *
X * added opterr & optopt     - Terrence W. Holm, Aug. 1988
X */
X
X#include <stdio.h>
X
Xchar	*optarg;	/* Global argument pointer. */
Xint	optind = 0;	/* Global argv index. */
Xint	opterr = 1;	/* Print error flag, default = on */
Xint	optopt;
X
Xstatic char	*scan = NULL;	/* Private scan pointer. */
X
Xextern char	*strchr();
X
Xint
Xgetopt(argc, argv, optstring)
Xint argc;
Xchar *argv[];
Xchar *optstring;
X{
X	register char c;
X	register char *place;
X
X	optarg = NULL;
X
X	if (scan == NULL || *scan == '\0') {
X		if (optind == 0)
X			optind++;
X	
X		if (optind >= argc || argv[optind][0] != '-' || argv[optind][1] == '\0')
X			return(EOF);
X		if (strcmp(argv[optind], "--")==0) {
X			optind++;
X			return(EOF);
X		}
X	
X		scan = argv[optind]+1;
X		optind++;
X	}
X
X	optopt = c = *scan++;
X	place = strchr(optstring, c);
X
X	if (place == NULL || c == ':') {
X		if ( opterr )
X			fprintf(stderr, "%s: unknown option -%c\n", argv[0], c);
X		return('?');
X	}
X
X	place++;
X	if (*place == ':') {
X		if (*scan != '\0') {
X			optarg = scan;
X			scan = NULL;
X		} else if (optind < argc) {
X			optarg = argv[optind];
X			optind++;
X		} else {
X			if ( opterr )
X				fprintf(stderr, "%s: -%c argument missing\n", argv[0], c);
X			return('?');
X		}
X	}
X
X	return(c);
X}
/
echo x - getopt.3
gres '^X' '' > getopt.3 << '/'
XSUBROUTINES
X    getopt(3)		- get option letter from argv
X
XINVOCATION
X    extern char *optarg;
X    extern int   optind;
X    extern int   opterr;
X    extern int   optopt;
X
X    int getopt( argc, argv, optstring )
X      int   argc;
X      char *argv[];
X      char *optstring;
X
XEXPLANATION
X    Getopt(3) is used to ease the process of scanning the
X    options on a command line. The <argc> and <argv> given
X    to main() are passed to getopt(3), as well as a string
X    naming all of the single character option names. If
X    an option allows an argument, then a ':' is put after
X    the name in <optstring>.
X
X    For example, the <optstring> "af:x" means that the
X    command accepts the options "-a", "-f" and "-x". The
X    "-f" option has an argument. When a command line is
X    entered the options without a following argument may
X    be grouped together, and there may be space between
X    the "-f" and its argument in the command line. For
X    example,
X
X	cmd -a -xf arg rest of line
X
X    After each call, main() must check the returned option
X    name and, if appropriate, the argument referenced by
X    <optarg>. Main() should continue to call getopt(3) until
X    it returns EOF, at which time main() can use <optind> to
X    determine how many items still remain on the command line.
X
X    The cases for getopt(3) returning EOF are: no more items
X    in the command line, an item does not start with a "-",
X    an item is simply "-" or an item is "--". In the latter
X    case, <optind> is incremented past this item.
X
X    Normally getopt(3) will print an error message on stderr
X    if either an unknown option is encountered or an option
X    is missing an argument. This output may be suppressed by
X    setting <opterr> to 0. Errors cause '?' to be returned and
X    <optopt> to be set to the offending option letter.
X
XRESULTS
X    o/w : Option character, <optarg> points to possible argument.
X    EOF : Finished scanning options, <optind> is next <argv>.
X    '?' : Encountered an illegal option, <optopt> is letter.
X
XAUTHOR
X    Henry Spencer
/
----------------------------------------------------------

		Terrence W. Holm
		  uw-beaver!uvicctr!tholm