I can't find any method of changing the cursor color in ncurses forms library from green to anything else. Googling and searching the manpage for cursor or color hasn't helped. Anyone know how this is done?
You can change the color by writing \e]12;COLOR\a or \033]12;COLOR\007, they all the same, here a simple example:
#include <stdio.h>
#include <unistd.h>
void cursor_set_color_string(const char *color) {
printf("\e]12;%s\a", color);
fflush(stdout);
}
int main(int argc, char **argv) {
cursor_set_color_string("yellow"); sleep(1);
cursor_set_color_string("gray"); sleep(1);
cursor_set_color_string("blue"); sleep(1);
cursor_set_color_string("red"); sleep(1);
cursor_set_color_string("brown"); sleep(1);
return 0;
}
Here is a list of the color names: Xterm Colors.
It looks like you can also use RGB color in the form \e]12;#XXXXXX\a:
#include <stdio.h>
#include <unistd.h>
void cursor_set_color_rgb(unsigned char red,
unsigned char green,
unsigned char blue) {
printf("\e]12;#%.2x%.2x%.2x\a", red, green, blue);
fflush(stdout);
}
int main(int argc, char **argv) {
cursor_set_color_rgb(0xff, 0xff, 0xff); sleep(1);
cursor_set_color_rgb(0xff, 0xff, 0x00); sleep(1);
cursor_set_color_rgb(0xff, 0x00, 0xff); sleep(1);
cursor_set_color_rgb(0x00, 0xff, 0xff); sleep(1);
return 0;
}
Related
Trying to understand why this section of code using the cat command isn't working with execvp in C.
char *in[5] ={"cat", "file1.txt", ">>", "file2.txt", 0};
execvp(in[0], in);
When I run it displays the contents of file1.txt but then says:
cat: >> No such file or directory.
Then displays the contents of file2.txt
Why wouldn't it recognize the >> operator in this instance?
You can read the "man tee" command which it read from standard input and write to standard output and files. You could achieve this with below example.
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
/*
Implementation of below command:
cat file1.txt > file2.txt
*/
char *cmd1[] = { "/bin/cat", "file1.txt", 0 };
char *cmd2[] = { "tee", "file2.txt", 0 };
static void sigchld_hdl (int sig)
{
int status;
while (waitpid(-1, &status, 0) > 0) {
if(WIFEXITED(status))
printf("Child exited with code %d\n", WEXITSTATUS(status)); }
}
int runcmd(int pfd[])
{
int i=0;
switch (fork()) {
case -1:
perror ("fork");
return 1;
case 0:
dup2(pfd[0], 0);
close(pfd[1]); /* the child does not need this end of the pipe */
execvp(cmd2[0], cmd2);
perror(cmd2[0]);
exit(10);
default: /* parent */
dup2(pfd[1], 1);
close(pfd[0]); /* the parent does not need this end of the pipe */
execvp(cmd1[0], cmd1);
perror(cmd1[0]);
}
sleep(1);
}
int main (int argc, char *argv[])
{
struct sigaction act;
int fd[2];
pipe(fd);
memset (&act, 0, sizeof(act));
act.sa_handler = sigchld_hdl;
if (sigaction(SIGCHLD, &act, 0)) {
perror ("sigaction");
return 1;
}
runcmd(fd);
return 0;
}
I run the program on Ubuntu 12.04,
The counters' value is awalys 0.It seems that my counters didn't work for me.
When I run the program,the ouput is :
Get the number of CPU:8
Create counters for each CPU finished!
run_perf_stat()!
Cache miss in cpu1:0
Cache miss in cpu2:0
Cache miss in cpu3:0
Cache miss in cpu4:0
Cache miss in cpu5:0
Cache miss in cpu6:0
Cache miss in cpu7:0
Cache miss in cpu8:0
I can't make sense of the values'meaning.What I want to get is every cpu's cache reference and it's cache miss.But obviously the result seems not correct!
I have read the doc about the perf method at:
http://www.man7.org/linux/man-pages/man2/perf_event_open.2.html
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <asm-generic/unistd.h>
#include <dirent.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <asm/unistd.h>
#include "perf_event.h"
#define MAX_COUNTERS 256
static int fd[MAX_COUNTERS];
static unsigned int counter;
static unsigned int nr_cpus = 0; // amount of cpus
//open counter
long sys_perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
int cpu, int group_fd, unsigned long flags)
{
int ret;
ret = syscall(__NR_perf_event_open, hw_event, pid, cpu,
group_fd, flags);
return ret;
}
void run_perf_stat()
{
long long eventContents=0;
for (counter = 0; counter < nr_cpus; counter++){
if(fd[counter]!=-1){
read(fd[counter],&eventContents,sizeof(long long));
printf("Cache miss in cpu%d:%lld\n",counter+1,eventContents);
}
else{
fprintf(stderr, "Fail to read counter %d\n", counter);
}
}
}
int main(int argc, const char **argv){
DIR *dir; //access to dir
struct dirent *drp;
int run_count, p, pid;
struct timespec tim, tim2;
tim.tv_sec = 1; tim.tv_nsec = 0;
nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);// the number of CPU
printf("Get the number of CPU:%d\n",nr_cpus);
//create counters for each CPU (system-wide)
struct perf_event_attr attr; //cache miss
memset(&attr, 0, sizeof(struct perf_event_attr));
attr.type = PERF_TYPE_HARDWARE;
attr.config = PERF_COUNT_HW_CACHE_MISSES;
attr.size = sizeof(struct perf_event_attr);
attr.disabled = 0;
attr.read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |
PERF_FORMAT_TOTAL_TIME_RUNNING;
unsigned int cpu = 0;
for(cpu = 0; cpu < nr_cpus; cpu++)
fd[cpu] = sys_perf_event_open(&attr, -1, cpu, -1, 0);
printf("Create counters for each CPU finished!\n");
//get perf report
while (1) {
nanosleep(&tim , &tim2);
printf("run_perf_stat()!\n");
run_perf_stat();
}
return 1;
}
And I also run the example given at http://www.man7.org/linux/man-pages/man2/perf_event_open.2.html
But,unfortunaely,The result is always 0,too.Here comes the example in the man-page.
The following is a short example that measures the total instruction count of a call to printf(3).
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <asm/unistd.h>
long
perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
int cpu, int group_fd, unsigned long flags)
{
int ret;
ret = syscall(__NR_perf_event_open, hw_event, pid, cpu,
group_fd, flags);
return ret;
}
int
main(int argc, char **argv)
{
struct perf_event_attr pe;
long long count;
int fd;
memset(&pe, 0, sizeof(struct perf_event_attr));
pe.type = PERF_TYPE_HARDWARE;
pe.size = sizeof(struct perf_event_attr);
pe.config = PERF_COUNT_HW_INSTRUCTIONS;
pe.disabled = 1;
pe.exclude_kernel = 1;
pe.exclude_hv = 1;
fd = perf_event_open(&pe, 0, -1, -1, 0);
if (fd == -1) {
fprintf(stderr, "Error opening leader %llx\n", pe.config);
exit(EXIT_FAILURE);
}
ioctl(fd, PERF_EVENT_IOC_RESET, 0);
ioctl(fd, PERF_EVENT_IOC_ENABLE, 0);
printf("Measuring instruction count for this printf\n");
ioctl(fd, PERF_EVENT_IOC_DISABLE, 0);
read(fd, &count, sizeof(long long));
printf("Used %lld instructions\n", count);
close(fd);
}
I just tried your code and removing following lines (line no 75,76) makes the code work for me.
attr.read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |
PERF_FORMAT_TOTAL_TIME_RUNNING;
I have a small network consisting of 2 hosts (OS X and linux) with a switch between them. When I run the following pair of programs, the receiver (linux) doesn't see any multicast packets. However, when I run
tcpdump -i eth0 -s 512 udp
on the linux box, everything starts to work. Can someone tell me why running tcpdump enables this to work?
Note that both machines have IPv6 enabled (if that matters). The host addresses in the code are the IPv4 addresses of the local interfaces.
On the OS X machine, I run:
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define BUFLEN 256
int s;
int count;
struct in_addr local_address;
struct sockaddr_in multicast_address;
char buffer[BUFLEN];
int
main (int argc, char *argv[]) {
int port = 12345;
int retval = 0;
char *host_ip = "192.168.1.31";
char *multicast_ip = "224.0.0.251";
count = (int)time(NULL);
s = socket(AF_INET, SOCK_DGRAM, 0);
printf("s=%d\n", s);
local_address.s_addr = inet_addr(host_ip);
retval = setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, (char *)&local_address, sizeof(local_address));
printf("setsockopt=%d\n", retval);
memset((char *)&multicast_address, 0, sizeof(multicast_address));
multicast_address.sin_family = AF_INET;
multicast_address.sin_addr.s_addr = inet_addr(multicast_ip);
multicast_address.sin_port = htons(port);
while (1) {
sprintf(buffer, "Message number %d", count);
count++;
retval = sendto(s, buffer, BUFLEN, 0, (struct sockaddr*)&multicast_address, sizeof(multicast_address));
printf("sendto=%d\n", retval);
sleep(3);
}
return 0;
}
On the linux box, I run:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define BUFLEN 256
int s;
struct ip_mreq multicast_group;
struct sockaddr_in localSock;
char buffer[BUFLEN];
int
main(int argc, char *argv[]) {
int reuse = 1;
int retval = 0;
int port = 12345;
char *host_ip = "192.168.1.131";
char *multicast_ip = "224.0.0.251";
s = socket(AF_INET, SOCK_DGRAM, 0);
printf("s = %d\n", s);
setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&reuse, sizeof(reuse));
printf("REUSEADDR = %d\n", retval);
memset((char *) &localSock, 0, sizeof(localSock));
localSock.sin_family = AF_INET;
localSock.sin_port = htons(port);
localSock.sin_addr.s_addr = INADDR_ANY;
retval = bind(s, (struct sockaddr*)&localSock, sizeof(localSock));
printf("bind = %d\n", retval);
multicast_group.imr_multiaddr.s_addr = inet_addr(multicast_ip);
multicast_group.imr_interface.s_addr = inet_addr(host_ip);
retval = setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *)&multicast_group, sizeof(multicast_group));
printf("ADD_MEMBERSHIP = %d\n", retval);
while (1) {
retval = read(s, buffer, BUFLEN);
printf("%d => [%s]\n", retval, buffer);
}
return 0;
}
Thanks.
What is the best possible way to send packets coming on an interface back to the same interface without changing anything in the packet. I want to have a loopback effect for the actual traffic coming on one of my interfaces e.g eth0
I think you can easily achieve this with Python/Scapy. Something like
sniff(iface="eth0", prn=lambda x: sendp(x, iface="eth0"))
should do it.
I don't think you can do this easily with a physical interface. I used the tap module for this purpose, though. It's quite simple: I create a new tap interface, and my program writes back everything that is read from the device. I used this to test a proprietary network protocol - so it might or might not work for what you intend to do. The code is quite simple:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/if_tun.h>
#define DEVNAME "gnlo0"
static int tun_alloc(char *dev)
{
struct ifreq ifr;
int fd, ret;
if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
perror("open");
return -1;
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP;
if (*dev)
strncpy(ifr.ifr_name, dev, IFNAMSIZ);
ret = ioctl(fd, TUNSETIFF, (void *)&ifr);
if (ret < 0) {
close(fd);
perror("ioctl TUNSETIFF");
return ret;
}
strcpy(dev, ifr.ifr_name);
return fd;
}
int main(int argc, char **argv)
{
int fd = -1;
int ret = 1;
char dev[IFNAMSIZ];
strncpy(dev, DEVNAME, IFNAMSIZ - 1);
printf("opening %s\n", dev);
fd = tun_alloc(dev);
if (fd < 0)
goto out;
char buf[512];
snprintf(buf, sizeof(buf) - 1,
"ip addr flush dev %s; ip link set dev %s up", dev, dev);
if (system(buf) < 0) {
perror("system");
goto out;
}
while (1) {
unsigned char packet[65535];
int len = read(fd, packet, sizeof(packet));
if (len < 0) {
perror("read");
goto out;
}
printf("incoming packet [%d octets]\n", len);
len = write(fd, packet, len);
printf("fed back packet [%d octets]\n", len);
}
ret = 0;
out:
if (fd >= 0)
close(fd);
return ret;
}
#include <pthread.h>
#ifndef __linux__
#include <windows.h>// to include the windows.h library//
#endif
#include <stdio.h>
#include <stdlib.h>
#define NUM_THREADS 5
#include <sys/timeb.h>
void *PrintHello(void *threadid)
{
srand(time(NULL));
long tid,a;
tid = (long)threadid;
a=rand()%5;
printf("Hello World! It's me, thread #%ld!%ld\n", tid,a);
pthread_exit(NULL);
}
int main (int argc, char *argv[])
{
pthread_t threads[NUM_THREADS];
int rc;
long t,a;
srand(time(NULL));
for(t=0; t<NUM_THREADS; t++){
a=rand()%5;
printf("In main: creating thread %ld,%ld\n", t,a);
rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
if (rc){
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
}
/* Last thing that main() should do */
pthread_exit(NULL);
}
Alright I have this simple code and when I compile it inside the main() the random numbers
are different from one another but when i try to generate random numbers inside the threads, all the numbers that are produced are the same.
Try seeding from outside the threads. The problem is that you get the same seed for each thread