I need to execute this script from my Python script. Is it possible? The script generate some outputs with some files being written. How do I access these files? I have tried with subprocess call function but without success. fx@fx-ubuntu:~/Documents/projects/foo$ bin/bar -c somefile.xml -d text.txt -r aString -f anotherString >output ...
In my python script, I need to call within a for loop an executable, and waiting for that executable to write the result on the "output.xml". How do I manage to use wait() & how do I know when one of my executable is finished generating the result to get the result? How do I close that process and open a new one to call again the execut...
Are there any alternatives to stat (which is found on most Unix systems) which can determine the file type? The manpage says that a call to stat is expensive, and I need to call it quite often in my app. ...
Hello, given the following code (it's supposed to write "hellowolrd" in a "helloworld" file, and then read the text): #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #define FNAME "helloworld" int main(){ int filedes, nbytes; char buf[128]; /* Creates a file */ if((filedes=open(FNAME, O_CREAT | O_EXCL...
I'm doing some experimenting and would like to be able to see what is saved on the stack during a system call (the saved state of the user land process). According to http://lxr.linux.no/#linux+v2.6.30.1/arch/x86/kernel/entry_32.S it shows that the various values of registers are saved at those particular offsets to the stack pointer. He...
Hi all, I want to write a signal handler to catch SIGSEGV. First , I would protect a block of memory for read or writes using char *buffer; char *p; char a; int pagesize = 4096; " mprotect(buffer,pagesize,PROT_NONE) " What this will do is , it will protect the memory starting from buffer till pagesize for any reads or writes. ...
Where are some lists of system calls on UNIX? This wasn't my original question, but thanks anyway :) ...
I'm trying to execute a program (convert from ImageMagick, to be specific) whose parent folder exists on the path. Ergo, when I run convert from the command line, it runs the command. The following, however, fails: String command = "convert" CommandLine commandLine = CommandLine.parse(command); commandLine.addArgument(...) ... int exitV...
Sometime back I used a windows tool to see what a process is doing. This tool allowed me to inspect functions exported from DLL. It also allowed me to change the values passed to a function on the fly. I cannot recollect the name(not sure if that was free or commercial one). Could any one point to me solution that can do this? (Tools ...
I want to be able to map memory to a file descriptor so I can use some existing functions that need a file descriptor. Here's essentially what I'm looking for: void do_operation1(int fd); char data[DATA_MAX] = { /* embedded binary data */ }; int fd = addr_to_fd(data, DATA_MAX); do_operation1(fd); /* ... operate on fd ... */ What sy...
Hi all, I wanted to know how can i use strace function to trace system calls in my C program and also use it for debugging my code. regs adi ...
Does anyone tell me how to block some specific system calls within a program, please? I am building a system which takes a piece of C source code, compiles it with gcc and runs it. For security reasons, I need to prevent the compiled program from calling some system calls. Is there any way to do it, from the source code level (e.g. strip...
Background: This is a follow-up question to this thread about handling EINTR for system calls in C++ (Linux/GCC). Regardless of whether or not I intend to profile my application, it seems like I should be handling system calls setting errno to EINTR as a special case. There are many, many, many opinions about the use of goto. My quest...
Hi, I'm using unix system() calls to gunzip and gzip files. With very large files sometimes (i.e. on the cluster compute node) these get aborted, while other times (i.e. on the login nodes) they go through. Is there some soft limit on the time a system call may take? What else could it be? ...
I've written a web crawler that I'd like to be able to stop via the keyboard. I don't want the program to die when I interrupt it; it needs to flush its data to disk first. I also don't want to catch KeyboardInterruptedException, because the persistent data could be in an inconsistent state. My current solution is to define a signal h...
Some (many? all?) 64-bit1 Linux distros allow running 32-bit applications by shipping parallel collections of 32-bit and 64-bit libraries (including libc). So a 32-bit application can link against 32-bit libs and be run by a 64-bit kernel. I'd like to know the mechanics of how 32-bit applications make system calls on a 64-bit kernel. I ...
I'm learning asm on Linux (noobuntu 10.04) I got the following code off of: http://asm.sourceforge.net/intro/hello.html section .text global _start ;must be declared for linker (ld) _start: ;tell linker entry point mov edx,len ;message length mov ecx,msg ;message to write mov ebx,1 ;file descriptor (stdout) mov eax,4 ;system call numb...
I'm trying to get PHP to make system calls on OS X. However, it doesn't seem to be able to find anything that's included in the system path. When I run... putenv("PATH={$_SERVER["PATH"]}:/usr/local/bin"); ... just before the system call, it works. This is not a practical solution, since the code that executes the system call is a plug...
Can anyone explain how malloc() works internally? I have sometimes done strace program and I see a lot of sbrk system calls, doing man sbrk talks about it being used in malloc() but not much more. I'd really like to learn how malloc() works. Thanks, Boda Cydo. ...
Hello: A series of applications I'm writing require that the user be able to read from a filesystem with KLOG authentication. Some functions require the user to have KLOG tokens (i.e., be authenticated) and others don't. I wrote a small Python decorator so that I can refactor the "you must be KLOGed" functionality within my modules: # ...