ref: 5d202d345616907d511b46e395226958fe66a2c3
dir: /sys/src/cmd/aux/rdwr.c/
#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"); } } }