GETFLAGS(9.2) GETFLAGS(9.2)
NAME
getflags, usage - process flag arguments in argv
SYNOPSIS
#include <libg.h>
#include <fb.h>
int getflags(int argc, char *argv[], char
int usage(char *tail)
extern char **flag[], cmdline[], *cmdname, *flagset[];
DESCRIPTION
Getflags digests an argument vector argv, finding flag argu-
ments listed in flags. Flags is a string of flag letters. A
letter followed by a colon and a number is expected to have
the given number of parameters. A flag argument starts with
`-' and is followed by any number of flag letters. A flag
with one or more parameters must be the last flag in an
argument. If any characters follow it, they are the flag's
first parameter. Otherwise the following argument is the
first parameter. Subsequent parameters are taken from sub-
sequent arguments.
The global array flag is set to point to an array of parame-
ters for each flag found. Thus, if flag -x was seen,
flag['x'] is non-zero, and flag['x'][i] is the flag's ith
parameter. If flag -x has no parameters flag['x']==flagset.
Flags not found are marked with a zero. Flags and their
parameters are deleted from argv. Getflags returns the
adjusted argument count.
Getflags stops scanning for flags upon encountering a non-
flag argument, or the argument --, which is deleted.
Getflags places a pointer to argv[0] in the external vari-
able cmdname. It also concatenates the original members of
argv, separated by spaces, and places the result in the
external array cmdline.
Usage constructs a usage message, prints it on the standard
error file, and exits with status 1. The command name
printed is argv[0]. Appropriate flag usage syntax is gener-
ated from flags. As an aid, explanatory information about
flag parameters may be included in flags in square brackets
as in the example. Tail is printed at the end of the mes-
sage. If getflags encountered an error, usage tries to
indicate the cause.
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GETFLAGS(9.2) GETFLAGS(9.2)
EXAMPLES
main(int argc, char *argv[]){
if((argc=getflags(argc, argv, "vinclbhse:1[expr]", 1))==-1)
usage("[file ...]");
}
might print:
Illegal flag -u
Usage: grep [-vinclbhs] [-e expr] [file ...]
SEE ALSO
ARG(2)
DIAGNOSTICS
Getflags returns -1 on error: a syntax error in flags, set-
ting a flag more than once, setting a flag not mentioned in
flags, or running out of argv while collecting a flag's
parameters.
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