finish npc

wip/npc/Makefile

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+npc: npc.c

wip/npc/npc.1

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+.TH npc 1
+
+.SH NAME
+
+npc \(en show non-printing characters
+
+.SH SYNOPSIS
+
+npc
+.RB ( -eht )
+
+.SH DESCRIPTION
+
+Npc reads from standard input and writes to standard output, replacing non-
+printing characters with printable equivalents. Control characters print as a
+carat ('^') followed by the character '@' through '_' corresponding to the
+character replaced (e.g. control-X becomes "^X"). The delete character (0x7F)
+becomes "^?". Characters with the high bit set (>127) are printed as "M-"
+followed by the graphical representation for the same character without the
+high bit set.
+.PP
+The
+.B -e
+option prints a currency sign ('$') before each line ending.
+.PP
+The
+.B -t
+option prints tab characters as "^I" rather than a literal horizontal tab.
+
+.SH DIAGNOSTICS
+
+Npc prints a debug message and exits with the appropriate sysexits(3) error
+code in the event of an error, otherwise it exits successfully.
+
+.SH STANDARDS
+
+None.
+
+.SH COPYRIGHT
+
+Public domain.
+
+.SH SEE ALSO
+
+cat(1), cat-v(1)
+.PP
+"UNIX Style, or cat -v Considered Harmful" by Rob Pike

wip/npc/npc.c

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+#include <stdio.h> /* fprintf(3), fputs(3), getc(3), putc(3), stdin, stdout,
+                    * EOF */
+#include <unistd.h> /* getopt(3) */
+#if !defined EX_USAGE || !defined EX_OK
+#	include <sysexits.h>
+#endif
+
+static char *program_name = "npc";
+
+int main(int argc, char *argv[]){
+	int c;
+	char showend;
+	char showtab;
+
+	showend = 0;
+	showtab = 0;
+
+	if(argc > 0)
+		while((c = getopt(argc, argv, "et")) != -1)
+			switch(c){
+			case 'e':	showend = 1; break;
+			case 't':	showend = 1; break;
+			default:	goto usage;
+			}
+
+	if(optind > argc){
+usage:		fprintf(stderr,
+			"Usage: %s (-eht)\n",
+			argv[0] == NULL ? program_name : argv[0]);
+		return EX_USAGE;
+	}
+
+	while((c = getc(stdin)) != EOF){
+		if(c > 127){
+			fputs("M-", stdout);
+			c -= 128;
+		}
+		switch(c){
+		case 127:	fputs("^?", stdout);
+				break;
+		case '\n':	if(showend)
+					putc('$', stdout);
+		default:
+			if(c >= ' ' || c == '\n' || (!showtab && c == '\t'))
+				putc(c, stdout);
+			else
+				fprintf(stdout, "^%c", c + '@');
+		}
+	}
+
+	return EX_OK;
+}