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#include <u.h>
#include <libc.h>
int wrrd;
void
usage(void)
{
fprint(2, "usage: rdwr [-w] file\n");
exits("usage");
}
void
main(int argc, char **argv)
{
int fd;
char buf[8192];
int n;
ARGBEGIN{
case 'w':
wrrd = 1;
break;
default:
usage();
}ARGEND;
if(argc != 1)
usage();
if((fd = open(argv[0], ORDWR)) < 0)
sysfatal("open: %r");
if(wrrd){
n = read(fd, buf, sizeof buf);
if(n < 0)
fprint(2, "read error: %r\n");
else{
write(1, buf, n);
print("\n");
}
}
while(print("> "), (n = read(0, buf, 1000)) > 0) {
seek(fd, 0, 0);
if(write(fd, buf, n-1) != n-1) /* n-1: no newline */
fprint(2, "write error: %r\n");
seek(fd, 0, 0);
n = read(fd, buf, sizeof buf);
if(n < 0)
fprint(2, "read error: %r\n");
else{
write(1, buf, n);
print("\n");
}
}
}
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