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_@ -9,6 +9,9 @@
.br
.B read
[
+.B -c
+] [
+[
.B -m
] [
.B -n
_AT_@ -62,6 +65,18 @@
.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_@ -3,6 +3,7 @@
int multi;
int nlines;
+vlong nchars;
char *status = nil;
int
_AT_@ -53,29 +54,60 @@
}
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_@ -83,7 +115,7 @@
fprint(2, "read: can't open %s: %r\n", argv[i]);
exits("open");
}
- lines(fd, argv[i]);
+ (*proc)(fd, argv[i]);
close(fd);
}
Received on Mon Jul 02 2012 - 20:44:38 CEST