Search DaniWeb - vfork

Re: Behaviour of program in exit vs return with vfork 13 Years Ago by Narue … in the child, it just ends the process. Since vfork() shares process memory between parent and child, letting the … a Bad Thing™. Technically, the way you're using vfork() is undefined regardless of your exit strategy, as allowed … are severely limited: [quote] (From POSIX.1) The vfork() function has the same effect as fork(2), except that… Behaviour of program in exit vs return with vfork 13 Years Ago by Efficience I have written a code for checking vfork in unix. But I am getting the ambiguous behavious.…of this behavior please ? I know in case of vfork same memory space is shared between parent and child but…pid,k=1; printf("Before fork \n"); pid = vfork(); if(pid == 0) { printf("I am a child … Re: Behaviour of program in exit vs return with vfork 13 Years Ago by Narue … closing any open file descriptor.[/QUOTE] IIRC, most versions of vfork() copy file descriptors, so closing them in the child is…, so once again I'll recommend using fork() instead of vfork(). The potential performance benefits aren't worth the risk. Re: Behaviour of program in exit vs return with vfork 13 Years Ago by Efficience … pid,k=1; printf("Before fork \n"); pid = vfork(); if(pid == 0) { printf("I am a child \n… Re: Behaviour of program in exit vs return with vfork 13 Years Ago by Efficience Hmm , I understand it now. Thanks a lot Narue. If child process is copying the descriptor their should not be such problem. Problem with basic templates on GCC 20 Years Ago by winbatch … -o Test /usr/lib/libstdc++.so: warning: reference to compatibility vfork(); include <unistd.h> for correct reference Test.o… creating a process in UNIX 15 Years Ago by want_to_code what are the ways that a process can be created in UNIX apart from fork/vfork? [Linux] Execve usage 15 Years Ago by Gonbe … fragment underneath shows my usage: [CODE="C"] childPID = vfork(); if (childPID == 0) { execve(input.process, input.parameters, environ); printf… execve problem: How to construct argument lists 15 Years Ago by QuantumMechanic … line sprintf(cmdstr,"%s/%s",UTILPATH,script_name); pid = vfork(); if (pid == -1) { // fork error code here } if (pid == 0… Re: variations in fread() buffering 14 Years Ago by nezachem …This is the output on Solaris in the case of vfork(): Segmentation Fault (core dumped) [/QUOTE] A vforked child… undefined behaviour. [QUOTE]MS-Windows creates threads just like vfork, where all threads share the same memory. [/QUOTE] …It does not. After vfork the parent process is blocked until the child does either… Re: variations in fread() buffering 14 Years Ago by Ancient Dragon [QUOTE] It does not. After vfork the parent process is blocked until the child does either…while sharing memory space. [/QUOTE] I have no clue how vfork() works -- I was just comparing the posted results with how… I posted and ran works just as you described for vfork() -- the win32 api function WaitForSingleObject() causes the thread to wait… Re: variations in fread() buffering 14 Years Ago by sree_ec … not be same but fp is same. Then I used vfork() instead of fork(), with the same program.. [just gave it… parent fp at 22; just like your solaris output. In vfork() parent and child uses the same memory space [shared] So… Re: variations in fread() buffering 14 Years Ago by sree_ec …;1331588]Thanks sree_ec. I added exit(0) for child (the vfork case) and it gave the same output as Solaris gives… parameter is also varying.So in the case we use vfork() and assume that it shares same fle pointer structure , we… Re: Need help passing data from child process to parent in simple fork() program 10 Years Ago by Kyle_4 You need to use vfork(). Here's an example. #include <iostream> #include <…; int num, sum=0; /*fork a child process*/ pid_t pid = vfork(); if(pid<0){ cout<<"fork failed… Re: Unknown prototype ... 17 Years Ago by invisal …(useconds_t, useconds_t); int unlink(const char *); int usleep(useconds_t); pid_t vfork(void); ssize_t write(int, const void *, size_t); [/code] Source: [url… Re: variations in fread() buffering 14 Years Ago by Ancient Dragon MS-Windows creates threads just like vfork, where all threads share the same memory. I didn't realize fork() creates new data space :-O Re: variations in fread() buffering 14 Years Ago by sree_ec [QUOTE=Ancient Dragon;1327960]MS-Windows creates threads just like vfork, where all threads share the same memory. I didn't … Re: variations in fread() buffering 14 Years Ago by Jishnu This is the output on Solaris in the case of vfork() [QUOTE]initial file handle :: 0 child read :: abcdefghij child file handle :: 11 parent file handle :: -1 Segmentation Fault (core dumped) [/QUOTE] I will add a detailed post later. Re: variations in fread() buffering 14 Years Ago by sree_ec [QUOTE=Jishnu;1328612]This is the output on Solaris in the case of vfork() I will add a detailed post later.[/QUOTE] we need to do a clean up before child terminates. So add an exit(0); or _exit(0); before the process terminates. This should solve the problem Re: variations in fread() buffering 14 Years Ago by Jishnu …[/QUOTE] Thanks sree_ec. I added exit(0) for child (the vfork case) and it gave the same output as Solaris gives… Re: variations in fread() buffering 14 Years Ago by Jishnu … parameter is also varying.So in the case we use vfork() and assume that it shares same fle pointer structure , we… Re: Segmentation Fault, and I know where it is 12 Years Ago by Ancient Dragon … = 2; for(i = 2; i < argc; i++) { pid_t pid = vfork(); if( pid == 0) { char* filename = argv[id]; id++; // ready for… Re: C dissecting protocol level 3 and application and url name in packet hex va 11 Years Ago by newbie14 … checking for strsep... yes checking for fork... yes checking for vfork... yes checking for strftime... yes checking for setlinebuf... yes checking… Re: C dissecting protocol level 3 and application and url name in packet hex va 11 Years Ago by newbie14 … checking for strsep... yes checking for fork... yes checking for vfork... yes checking for strftime... yes checking for setlinebuf... yes checking… Re: Problem with basic templates on GCC 20 Years Ago by 1o0oBhP not sure what is wrong there! However this code (untested) should work [CODE] #include <iostream> // std::cout #include <string> // std::string #include <cstdlib> // system template <class t> class mytemp { public: mytemp(t temp) { data = temp; } void print(void) { std::cout << data; }… Re: creating a process in UNIX 15 Years Ago by sknake [icode]exec[/icode] Re: creating a process in UNIX 15 Years Ago by 50701735 i think that create a process in unix is like nearly with create process in linux . you can use system called that is fork(),exec(), or system(); Re: [Linux] Execve usage 15 Years Ago by Salem The 'e' forms pass the environment. The 'p' forms (which you're not using) are the ones which search the PATH. Re: [Linux] Execve usage 15 Years Ago by gerard4143 execve info/man has really good example code towards the bottom of the topic. Here's what I did: [CODE] #include <stdio.h> #include <stdlib.h> #include <unistd.h> int main(int argc, char *argv[]) { char *newargv[] = { "/bin/ls", "-l", NULL }; char *newenviron[] = { NULL }; char *exeprog = &… Re: execve problem: How to construct argument lists 15 Years Ago by nezachem Few things are obvious right away: 1. cmdstr is not initialized. 2. my_env and my_args are not terminated by NULL. 3. A first element of my_args is a program name. The way you set the arguments up is not fatal, but highly unconventional. 4. You [I]must[/I] test the value returned by realloc. 5. You are working too hard. I'd just go with [CODE]char …