[9base] add read -c

          With the -c flag, read copies exactly nbytes of characters
          instead of lines. It is mutually exclusive with -n and -m
          flag.

-sl

diff -r c6943e63621b read/read.1
--- a/read/read.1	Thu Apr 19 18:17:26 2012 +0100
+++ b/read/read.1	Mon Jul 02 13:41:08 2012 -0500
 <at>  <at>  -9,6 +9,9  <at>  <at> 
 .br
 .B read
 [
+.B -c
+] [
+[
 .B -m
 ] [
 .B -n
 <at>  <at>  -62,6 +65,18  <at>  <at> 
 .I nline
 lines.
 .PP
+With the
+.B -c
+flag,
+.I read
+copies exactly
+.I nbytes
+of characters instead of lines. It is mutually exclusive with
+.B -n
+and
+.B -m
+flag.
+.PP
 .I Read
 always executes a single
 .B write
diff -r c6943e63621b read/read.c
--- a/read/read.c	Thu Apr 19 18:17:26 2012 +0100
+++ b/read/read.c	Mon Jul 02 13:41:08 2012 -0500
 <at>  <at>  -3,6 +3,7  <at>  <at> 

 int	multi;
 int	nlines;
+vlong	nchars;
 char	*status = nil;

 int
 <at>  <at>  -53,29 +54,60  <at>  <at> 
 }

 void
+chars(int fd, char *file)
+{
+	char buf[8*1024];
+	vlong m;
+	int n;
+
+	for(m = 0; m < nchars; m += n){
+		n = sizeof(buf);
+		if(n > (nchars - m))
+			n = nchars - m;
+		if((n = read(fd, buf, n)) < 0){
+			fprint(2, "read: error reading %s: %r\n", file);
+			exits("read error");
+		}
+		if(n == 0){
+			if(m == 0)
+				status = "eof";
+			break;
+		}
+		write(1, buf, n);
+	}
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: read [-m] [-n nlines] [-c nbytes] [files...]\n");
+	exits("usage");
+}
+
+void
 main(int argc, char *argv[])
 {
+	void (*proc)(int, char*);
 	int i, fd;
-	char *s;

+	proc = lines;
 	ARGBEGIN{
+	case 'c':
+		nchars = atoll(EARGF(usage()));
+		proc = chars;
+		break;
+	case 'n':
+		nlines = atoi(EARGF(usage()));
+		break;
 	case 'm':
 		multi = 1;
 		break;
-	case 'n':
-		s = ARGF();
-		if(s){
-			nlines = atoi(s);
-			break;
-		}
-		/* fall through */
 	default:
-		fprint(2, "usage: read [-m] [-n nlines] [files...]\n");
-		exits("usage");
+		usage();
 	}ARGEND

 	if(argc == 0)
-		lines(0, "<stdin>");
+		(*proc)(0, "<stdin>");
 	else
 		for(i=0; i<argc; i++){
 			fd = open(argv[i], OREAD);
 <at>  <at>  -83,7 +115,7  <at>  <at> 
 				fprint(2, "read: can't open %s: %r\n", argv[i]);
 				exits("open");
 			}
-			lines(fd, argv[i]);
+			(*proc)(fd, argv[i]);
 			close(fd);
 		}