term% cat index.txt 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 *flags)
int usage(char *tail)
extern char **flag[], cmdline[], *cmdname, *flagset[];
DESCRIPTION
Getflags digests an argument vector argv, finding flag arguments 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 subsequent arguments.
The global array flag is set to point to an array of parameters 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 argu‐
ment, or the argument --, which is deleted.
Getflags places a pointer to argv[0] in the external variable 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]. Appro‐
priate flag usage syntax is generated from flags. As an aid, explana‐
tory information about flag parameters may be included in flags in
square brackets as in the example. Tail is printed at the end of the
message. If getflags encountered an error, usage tries to indicate the
cause.
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 ...]
SOURCE
/sys/src/libfb/getflags.c
SEE ALSO
ARG(2)
DIAGNOSTICS
Getflags returns -1 on error: a syntax error in flags, setting a flag
more than once, setting a flag not mentioned in flags, or running out
of arguments while collecting a flag's parameters.
GETFLAGS(9.2)