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Code samples from Computer Networks I Lab Manual, Chapter 3 - Program I/O with the Getopt and Syslog Libraries
#include <stdio.h>
#include <stdlib.h>
#define NAME_LENGTH 20
int main()
{
char name[NAME_LENGTH];
printf("Please enter your name: ");
if (fgets(name, NAME_LENGTH, stdin) != NULL)
{
printf("Nice to meet you, %s", name);
}
exit(EXIT_SUCCESS);
}
#include <syslog.h>
#include <stdlib.h>
int main()
{
int i = 42;
char* str = "universe";
openlog("fig3-10", LOG_PERROR | LOG_PID | LOG_NDELAY, LOG_USER);
syslog(LOG_INFO, "The answer to the %s is %d", str, i);
closelog();
exit(EXIT_SUCCESS);
}
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
int main(int argc, char** argv)
{
FILE* file;
openlog("fig3-11", LOG_PERROR | LOG_PID | LOG_NDELAY, LOG_USER);
syslog(LOG_DEBUG, "Program started");
syslog(LOG_DEBUG, "Testing arguments");
syslog(LOG_DEBUG, "Arguments passed to the program: %d", argc);
// Check if a filename was passed as an argument
if (argc != 2)
{
syslog(LOG_ERR, "No filename specified");
closelog();
exit(EXIT_FAILURE);
}
// If so, open the file
syslog(LOG_DEBUG, "Opening file '%s'", argv[1]);
file = fopen(argv[1], "r");
// Ensure the file was opened successfully
if (file == NULL)
{
syslog(LOG_ERR, "The specified file could not be opened");
closelog();
exit(EXIT_FAILURE);
}
syslog(LOG_INFO, "The file '%s' exists and was successfully opened!", argv[1]);
close(file);
closelog();
exit(EXIT_SUCCESS);
}
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
int main(int argc, char** argv)
{
FILE* file;
setlogmask(LOG_UPTO(LOG_INFO));
openlog("fig3-12", LOG_PERROR | LOG_PID | LOG_NDELAY, LOG_USER);
syslog(LOG_DEBUG, "Program started");
syslog(LOG_DEBUG, "Testing arguments");
syslog(LOG_DEBUG, "Arguments passed to the program: %d", argc);
if (argc != 2)
{
syslog(LOG_ERR, "No filename specified");
closelog();
exit(EXIT_FAILURE);
}
syslog(LOG_DEBUG, "Opening file '%s'", argv[1]);
file = fopen(argv[1], "r");
if (file == NULL)
{
syslog(LOG_ERR, "The specified file could not be opened");
closelog();
exit(EXIT_FAILURE);
}
syslog(LOG_INFO, "The file '%s' exists and was successfully opened!", argv[1]);
close(file);
closelog();
exit(EXIT_SUCCESS);
}
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char** argv)
{
bool verbose = false;
char* log_filename;
int i;
// Iterate over the command line arguments
for (i = 1; i < argc; ++i)
{
// Check for the --verbose / -v flag
if (strcmp(argv[i], "--verbose") == 0 || strcmp(argv[i], "-v") == 0)
{
verbose = true;
}
// Check for the --log / -l flag
else if (strcmp(argv[i], "--log") == 0 || strcmp(argv[i], "-l") == 0)
{
// Ensure that an argument was provided
if (i + 1 == argc) {
fprintf(stderr, "The --log / -l option requires an argument\n");
exit(EXIT_FAILURE);
}
else {
log_filename = argv[++i];
}
}
}
printf("Verbose : %s\n", verbose ? "true" : "false");
printf("Log : %s\n", log_filename);
exit(EXIT_SUCCESS);
}
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <stdbool.h>
int main(int argc, char** argv)
{
int c;
bool verbose = false;
char* log_filename = NULL;
while ((c = getopt(argc, argv, "vl:")) != -1)
{
switch(c)
{
case 'v':
verbose = true;
break;
case 'l':
printf("-l called -- ignoring for now\n");
break;
case '?':
// Error message already printed by getopt -- we'll just exit
exit(EXIT_FAILURE);
break;
}
}
printf("Verbose : %s\n", verbose ? "true" : "false");
printf("Log : %s\n", log_filename);
exit(EXIT_SUCCESS);
}
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <stdbool.h>
int main(int argc, char** argv)
{
int c;
bool verbose = false;
char* log_filename = NULL;
while ((c = getopt(argc, argv, "vl:")) != -1)
{
switch(c)
{
case 'v':
verbose = true;
break;
case 'l':
log_filename = optarg;
break;
case '?':
// Error message already printed by getopt -- we'll just exit
exit(EXIT_FAILURE);
break;
}
}
printf("Verbose : %s\n", verbose ? "true" : "false");
printf("Log : %s\n", log_filename);
exit(EXIT_SUCCESS);
}
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <stdbool.h>
int main(int argc, char** argv)
{
int c, i;
bool verbose = false;
char* log_filename = NULL;
while ((c = getopt(argc, argv, "vl:")) != -1)
{
switch(c)
{
case 'v':
verbose = true;
break;
case 'l':
log_filename = optarg;
break;
case '?':
// Error message already printed by getopt -- we'll just exit
exit(EXIT_FAILURE);
break;
}
}
printf("Verbose : %s\n", verbose ? "true" : "false");
printf("Log : %s\n", log_filename);
for (i = optind; i < argc; ++i)
{
printf("Processing file %s\n", argv[i]);
}
exit(EXIT_SUCCESS);
}
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
int main(int argc, char** argv)
{
int c, i;
static int verbose_flag = 0;
char* log_filename = NULL;
while (1)
{
static struct option long_options[] =
{
{"verbose", no_argument, &verbose_flag, 1 },
{"log", required_argument, 0, 'l'},
{0, 0, 0, 0}
};
int option_index = 0;
c = getopt_long(argc, argv, "vl:", long_options, &option_index);
// If we've reached the end of the options, stop iterating
if (c == -1)
break;
switch (c)
{
case 'l':
log_filename = optarg;
break;
case 'v':
verbose_flag = 1;
break;
case '?':
// Error message already printed by getopt_long -- we'll just exit
exit(EXIT_FAILURE);
break;
}
}
printf("Verbose : %s\n", verbose_flag ? "true" : "false");
printf("Log : %s\n", log_filename);
for (i = optind; i < argc; ++i)
{
printf("Processing file %s\n", argv[i]);
}
exit(EXIT_SUCCESS);
}
#include <syslog.h>
#include <stdlib.h>
int main()
{
openlog("fig3-7", LOG_PID | LOG_NDELAY, LOG_USER);
syslog(LOG_NOTICE, "Hello Syslog!");
syslog(LOG_INFO, "Here's an informational message.");
syslog(LOG_WARNING, "Here's a warning.");
syslog(LOG_ERR, "Here's an error.");
syslog(LOG_DEBUG, "Here's some debugging information.\n");
closelog();
exit(EXIT_SUCCESS);
}
#include <syslog.h>
#include <stdlib.h>
int main()
{
openlog("fig3-8", LOG_PERROR | LOG_PID | LOG_NDELAY, LOG_USER);
syslog(LOG_NOTICE, "Hello Syslog!");
syslog(LOG_INFO, "Here's an informational message.");
syslog(LOG_WARNING, "Here's a warning.");
syslog(LOG_ERR, "Here's an error.");
syslog(LOG_DEBUG, "Here's some debugging information.\n");
closelog();
exit(EXIT_SUCCESS);
}
#include <syslog.h>
#include <stdlib.h>
void b()
{
syslog(LOG_DEBUG, "Entering b()");
syslog(LOG_DEBUG, "Leaving b()");
}
void a()
{
syslog(LOG_DEBUG, "Entering a()");
b();
syslog(LOG_DEBUG, "Leaving a()");
}
int main()
{
openlog("fig3-9", LOG_PERROR | LOG_PID | LOG_NDELAY, LOG_USER);
a();
closelog();
exit(EXIT_SUCCESS);
}
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