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UNIX for Advanced & Expert Users
forks....HELP!!! someone anyone?
Post 49624 by richardspence2 on Tuesday 6th of April 2004 03:36:31 PM
04-06-2004
fork...help
Hey,
check out this code... I tried running it with "fgets" as it states that "gets" is a dangerous code.... however, its not executing the linux commands... what could be the problem, or what in this code needs modification??
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <wait.h>
#define MAX 1024
void parse(char*buf, char ** args);
void execute(char**args);
int main()
{
char buf[MAX];
char *args[64];
for(;
{
/*Prompts for and reads a command*/
printf("Command: ");
if(fgets(buf, MAX, stdin) == '\0'){
printf("\n");
exit(0);
}
/*Splits the strings into arguments*/
parse(buf,args);
/*Executes the command*/
execute(args);
}
}
/* Parse: - Splits the commands in buf into individual arguments */
void parse(char*buf,char **args)
//char * buf;
//char ** args;
{
while(*buf != '\0'){
/*Strips the whitespace with the
use of null so previous argument
is terminated automatically*/
while(*buf == ' '|| *buf == '\t' || buf == '\n')
*buf++ = '\0';
/*Saves the argument*/
*args++ = buf;
/*Skips over the argument*/
while((*buf != '\0') && (buf != ' ') && (*buf != '\t') && (*buf != '\n'))
buf++;
}
*args = '\0';
}
/*Execute spawns the child process
and execute the program*/
void execute(char **args)
//char ** args;
{
pid_t pid;
int status;
/*Get a child process*/
if((pid = fork()) < 0){
perror("ERROR executing fork\n");
exit(1);
}
/*Child executes the code inside the if statement*/
if(pid == 0){
execvp(*args, args);
perror(*args);
exit(1);
}
/*The parent executes the wait*/
while (wait(&status) != pid)
/* empty */ ;
}
Thankx in advance.......
check out this code... I tried running it with "fgets" as it states that "gets" is a dangerous code.... however, its not executing the linux commands... what could be the problem, or what in this code needs modification??
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <wait.h>
#define MAX 1024
void parse(char*buf, char ** args);
void execute(char**args);
int main()
{
char buf[MAX];
char *args[64];
for(;
{/*Prompts for and reads a command*/
printf("Command: ");
if(fgets(buf, MAX, stdin) == '\0'){
printf("\n");
exit(0);
}
/*Splits the strings into arguments*/
parse(buf,args);
/*Executes the command*/
execute(args);
}
}
/* Parse: - Splits the commands in buf into individual arguments */
void parse(char*buf,char **args)
//char * buf;
//char ** args;
{
while(*buf != '\0'){
/*Strips the whitespace with the
use of null so previous argument
is terminated automatically*/
while(*buf == ' '|| *buf == '\t' || buf == '\n')
*buf++ = '\0';
/*Saves the argument*/
*args++ = buf;
/*Skips over the argument*/
while((*buf != '\0') && (buf != ' ') && (*buf != '\t') && (*buf != '\n'))
buf++;
}
*args = '\0';
}
/*Execute spawns the child process
and execute the program*/
void execute(char **args)
//char ** args;
{
pid_t pid;
int status;
/*Get a child process*/
if((pid = fork()) < 0){
perror("ERROR executing fork\n");
exit(1);
}
/*Child executes the code inside the if statement*/
if(pid == 0){
execvp(*args, args);
perror(*args);
exit(1);
}
/*The parent executes the wait*/
while (wait(&status) != pid)
/* empty */ ;
}
Thankx in advance.......
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LEARN ABOUT SUNOS
stat
stat.h(3HEAD) Headers stat.h(3HEAD) NAME
stat.h, stat - data returned by stat system call SYNOPSIS
#include <sys/types.h> #include <sys/stat.h> DESCRIPTION
The system calls stat, lstat and fstat return data in a stat structure, which is defined in <stat.h>. The constants used in the st_mode field are also defined in this file: #define S_IFMT /* type of file */ #define S_IAMB /* access mode bits */ #define S_IFIFO /* fifo */ #define S_IFCHR /* character special */ #define S_IFDIR /* directory */ #define S_IFNAM /* XENIX special named file */ #define S_INSEM /* XENIX semaphore subtype of IFNAM */ #define S_INSHD /* XENIX shared data subtype of IFNAM */ #define S_IFBLK /* block special */ #define S_IFREG /* regular */ #define S_IFLNK /* symbolic link */ #define S_IFSOCK /* socket */ #define S_IFDOOR /* door */ #define S_ISUID /* set user id on execution */ #define S_ISGID /* set group id on execution */ #define S_ISVTX /* save swapped text even after use */ #define S_IREAD /* read permission, owner */ #define S_IWRITE /* write permission, owner */ #define S_IEXEC /* execute/search permission, owner */ #define S_ENFMT /* record locking enforcement flag */ #define S_IRWXU /* read, write, execute: owner */ #define S_IRUSR /* read permission: owner */ #define S_IWUSR /* write permission: owner */ #define S_IXUSR /* execute permission: owner */ #define S_IRWXG /* read, write, execute: group */ #define S_IRGRP /* read permission: group */ #define S_IWGRP /* write permission: group */ #define S_IXGRP /* execute permission: group */ #define S_IRWXO /* read, write, execute: other */ #define S_IROTH /* read permission: other */ #define S_IWOTH /* write permission: other */ #define S_IXOTH /* execute permission: other */ The following macros are for POSIX conformance (see standards(5)): #define S_ISBLK(mode) block special file #define S_ISCHR(mode) character special file #define S_ISDIR(mode) directory file #define S_ISFIFO(mode) pipe or fifo file #define S_ISREG(mode) regular file #define S_ISSOCK(mode) socket file ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
stat(2), types.h(3HEAD), attributes(5), standards(5) SunOS 5.10 30 Aug 2002 stat.h(3HEAD)