Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site ut-sally.UUCP Path: utzoo!decvax!genrad!panda!talcott!harvard!seismo!ut-sally!jsq From: jsq@ut-sally.UUCP (John Quarterman) Newsgroups: mod.std.unix Subject: Re: command line arguments Message-ID: <2256@ut-sally.UUCP> Date: Thu, 4-Jul-85 10:54:39 EDT Article-I.D.: ut-sally.2256 Posted: Thu Jul 4 10:54:39 1985 Date-Received: Thu, 4-Jul-85 22:18:30 EDT References: <2210@ut-sally.UUCP> <2226@ut-sally.UUCP>, <2244@ut-sally.UUCP> <2255@ut-sally.UUCP> Organization: U. Texas CS Dept., Austin, Texas Lines: 433 Approved: jsq@ut-sally.UUCP From: John Quarterman (moderator)Topic: yet more on getopt (command line arguments) Two more messages, the first a followup to a previous posting, and the second public domain sources and man pages for getopt(3) and getopt(1). -mod ---------------------------------------------------------------------- From: ihnp4!utzoo!henry Date: 3 Jul 85 18:34:41 CDT (Wed) To: ihnp4!ut-sally!std-unix Subject: Re: command line arguments > > A group of bundled options may end with an option that has an argument. > > This creates confusion in using C-Kermit when you want to send an image > file. For example: > > send -is filename < --- works fine > send -si filename < --- bombs the program The AT&T syntax standard (which getopt does not completely enforce) actually forbids both of these usages. Options with arguments are not allowed to be bundled, and they must be separated from their arguments by a space. > I would *much* prefer to bundle the flags, then > have those with arguments pick them up in the same order as the flags are > listed. The few existing commands that use such a convention, notably tar(1), are (in my experience) the worse for it. It's seriously error-prone. I think the AT&T people did the right thing. ------------------------------ Date: Tue, 2 Jul 85 13:07:09 edt From: ihnp4!utcs!ian (Ian F. Darwin) To: ihnp4!ut-sally!jsq@tzec.UTEXAS.ARPA Subject: here is getopt Here is the source for getopt(3), the function that should be in everybody's C program, and getopt(1), a program that uses it to make shell programs comprehensible and consistent. There are man pages for both. Please send these on to the mod. group. Thanks. [ I have hacked the following shell script slightly so that it doesn't extract directly into system source directories, rather into the current directory. It should be assumed that this code comes with no warranty from me, Ian Darwin, or anyone else as to whether it accurately represents getopt as distributed with System V, or any command line standard, or that it works at all, or that it will cause no damage when extracted or used. -mod] #! /bin/sh #! To unbundle, sh this file echo x - "(/usr/man/man3/getopt.3)" >&2 echo x - mkdir lib >&2 mkdir lib >&2 echo x - lib/getopt.3 >&2 cat >lib/getopt.3 <<"//SYSIN DD SYSOUT=BD" .TH GETOPT 3 local .DA 25 March 1982 .SH NAME getopt \- get option letter from argv .SH SYNOPSIS .ft B int getopt(argc, argv, optstring) .br int argc; .br char **argv; .br char *optstring; .sp extern char *optarg; .br extern int optind; .ft .SH DESCRIPTION .I Getopt returns the next option letter in .I argv that matches a letter in .IR optstring . .I Optstring is a string of recognized option letters; if a letter is followed by a colon, the option is expected to have an argument that may or may not be separated from it by white space. .I Optarg is set to point to the start of the option argument on return from .IR getopt . .PP .I Getopt places in .I optind the .I argv index of the next argument to be processed. Because .I optind is external, it is normally initialized to zero automatically before the first call to .IR getopt . .PP When all options have been processed (i.e., up to the first non-option argument), .I getopt returns .BR EOF . The special option .B \-\- may be used to delimit the end of the options; .B EOF will be returned, and .B \-\- will be skipped. .SH SEE ALSO getopt(1) .SH DIAGNOSTICS .I Getopt prints an error message on .I stderr and returns a question mark .RB ( ? ) when it encounters an option letter not included in .IR optstring . .SH EXAMPLE The following code fragment shows how one might process the arguments for a command that can take the mutually exclusive options .B a and .BR b , and the options .B f and .BR o , both of which require arguments: .PP .RS .nf main(argc, argv) int argc; char **argv; { int c; extern int optind; extern char *optarg; \&. \&. \&. while ((c = getopt(argc, argv, "abf:o:")) != EOF) switch (c) { case 'a': if (bflg) errflg++; else aflg++; break; case 'b': if (aflg) errflg++; else bproc(); break; case 'f': ifile = optarg; break; case 'o': ofile = optarg; break; case '?': default: errflg++; break; } if (errflg) { fprintf(stderr, "Usage: ..."); exit(2); } for (; optind < argc; optind++) { \&. \&. \&. } \&. \&. \&. } .RE .PP A template similar to this can be found in .IR /usr/pub/template.c . .SH HISTORY Written by Henry Spencer, working from a Bell Labs manual page. Behavior believed identical to the Bell version. .SH BUGS It is not obvious how `\-' standing alone should be treated; this version treats it as a non-option argument, which is not always right. .PP Option arguments are allowed to begin with `\-'; this is reasonable but reduces the amount of error checking possible. .PP .I Getopt is quite flexible but the obvious price must be paid: there is much it could do that it doesn't, like checking mutually exclusive options, checking type of option arguments, etc. //SYSIN DD SYSOUT=BD echo x - "(/usr/man/man1/getopt.1)" >&2 echo x - mkdir bin >&2 mkdir bin >&2 echo x - bin/getopt.1 >&2 cat >bin/getopt.1 <<"//SYSIN DD SYSOUT=BD" .TH GETOPT 1 local .DA 12 April 1984 .SH NAME getopt \- parse command options .SH SYNOPSIS .B set \-\- \`getopt optstring .B $*\` .SH DESCRIPTION .I Getopt is used to break up options in command lines for easy parsing by shell procedures, and to check for legal options. .I Optstring is a string of recognized option letters (see .IR getopt (3)); if a letter is followed by a colon, the option is expected to have an argument which may or may not be separated from it by white space. The special option .B \-\- is used to delimit the end of the options. .I Getopt will place .B \-\- in the arguments at the end of the options, or recognize it if used explicitly. The shell arguments (\fB$1 $2\fR ...) are reset so that each option is preceded by a .B \- and in its own shell argument; each option argument is also in its own shell argument. .SH EXAMPLE The following code fragment shows how one might process the arguments for a command that can take the options .B a and .BR b , and the option .BR o , which requires an argument. .PP .RS .nf set \-\- \`getopt abo: $*\` if test $? != 0 then echo 'Usage: ...' exit 2 fi for i do case "$i" in \-a|\-b) flag=$i; shift;; \-o) oarg=$2; shift; shift;; \-\-) shift; break;; esac done .fi .RE .PP This code will accept any of the following as equivalent: .PP .RS .nf cmd \-aoarg file file cmd \-a \-o arg file file cmd \-oarg -a file file cmd \-a \-oarg \-\- file file .RE .PP A program template similar to this example can be found in .IR /usr/pub/template.sh . .SH SEE ALSO sh(1), getopt(3) .SH DIAGNOSTICS .I Getopt prints an error message on the standard error output when it encounters an option letter not included in .IR optstring . .SH HISTORY Written by Henry Spencer, working from a Bell Labs manual page. Behavior believed identical to the Bell version. .SH BUGS Whatever .IR getopt (3) has. .PP Arguments containing white space or imbedded shell metacharacters generally will not survive intact; this looks easy to fix but isn't. .PP The error message for an invalid option is identified as coming from .I getopt rather than from the shell procedure containing the invocation of .IR getopt ; this again is hard to fix. .PP The precise best way to use the .I set command to set the arguments without disrupting the value(s) of shell options varies from one shell version to another. //SYSIN DD SYSOUT=BD echo x - "(/usr/src/lib/libc/gen/getopt.c)" >&2 echo x - lib/getopt.c >&2 cat >lib/getopt.c <<"//SYSIN DD SYSOUT=BD" /* * getopt - get option letter from argv */ #include char *optarg; /* Global argument pointer. */ int optind = 0; /* Global argv index. */ static char *scan = NULL; /* Private scan pointer. */ extern char *index(); int getopt(argc, argv, optstring) int argc; char *argv[]; char *optstring; { register char c; register char *place; optarg = NULL; if (scan == NULL || *scan == '\0') { if (optind == 0) optind++; if (optind >= argc || argv[optind][0] != '-' || argv[optind][1] == '\0') return(EOF); if (strcmp(argv[optind], "--")==0) { optind++; return(EOF); } scan = argv[optind]+1; optind++; } c = *scan++; place = index(optstring, c); if (place == NULL || c == ':') { fprintf(stderr, "%s: unknown option -%c\n", argv[0], c); return('?'); } place++; if (*place == ':') { if (*scan != '\0') { optarg = scan; scan = NULL; } else if (optind < argc) { optarg = argv[optind]; optind++; } else { fprintf(stderr, "%s: -%c argument missing\n", argv[0], c); return('?'); } } return(c); } //SYSIN DD SYSOUT=BD echo x - "(/usr/src/bin/getopt.c)" >&2 echo x - bin/getopt.c >&2 cat >bin/getopt.c <<"//SYSIN DD SYSOUT=BD" #include main(argc, argv) int argc; char *argv[]; { extern int optind; extern char *optarg; int c; int status = 0; optind = 2; /* Past the program name and the option letters. */ while ((c = getopt(argc, argv, argv[1])) != EOF) switch (c) { case '?': status = 1; /* getopt routine gave message */ break; default: if (optarg != NULL) printf(" -%c %s", c, optarg); else printf(" -%c", c); break; } printf(" --"); for (; optind < argc; optind++) printf(" %s", argv[optind]); printf("\n"); exit(status); } //SYSIN DD SYSOUT=BD exit 0 ---------------------------------------------------------------------- -- John Quarterman, jsq@ut-sally.ARPA, {ihnp4,seismo,ctvax}!ut-sally!jsq