ref: 6009b7c2afc987944217138f570ba35b16aac5e4
parent: 0843a94f9a747e9cfb6266e74a90220e487e8f61
author: cinap_lenrek <cinap_lenrek@gmx.de>
date: Mon Jul 2 13:46:21 EDT 2012
read: add -c flag to copy bytes instead of lines
--- a/sys/man/1/cat
+++ b/sys/man/1/cat
@@ -12,8 +12,11 @@
.B -m
] [
.B -n
-.I nline
+.I nlines
] [
+.B -c
+.I nbytes
+] [
.I file ...
]
.SH DESCRIPTION
@@ -54,8 +57,20 @@
flag causes it to continue reading and writing multiple lines until end of file;
.B -n
causes it to read no more than
-.I nline
+.I nlines
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
--- a/sys/src/cmd/read.c
+++ b/sys/src/cmd/read.c
@@ -3,6 +3,7 @@
int multi;
int nlines;
+vlong nchars;
char *status = nil;
int
@@ -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);
@@ -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);
}
--
⑨