The system-calls tag has no wiki summary.
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Tracing system call on Ubuntu 12.04
The main task I have to carry out, is to trace the system call of processes in ubuntu 12.04 LTS.
Problem is, I am unable to trace them continuously, i.e. as soon as they are added to the system, they ...
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1answer
37 views
System call tracing [closed]
I am working on system call tracing for host based IDS, i need to trace a process as soon as it entered in the system (a new entry in /proc). Is there any interrupt or signal or kernel datastructure ...
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2answers
33 views
Importance of knowing if a standard library function is executing a system call [closed]
Is it actually important for a programmer to know if the standard library function he/she is using is actually executing a system call? If so, why?
Intuitively I'm guessing the only importance is in ...
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1answer
30 views
Understanding a XINU system call - getstk.c [closed]
I am having trouble conceptually understanding what is going on towards the end of this system call, and why. I understand the getstk.c method returns the highest memory address of available space, ...
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3answers
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How can you change the process name of Wing IDE from python to something more descriptive
In my process list under Ubuntu (using top/System Monitor) one of the largest memory hogs (200+Mb) was python. I searched a bit for one of my programs to be the cause until I realised this was my ...
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3answers
195 views
Command to trace rsh server to check behaviour of particular system call
I am working with rsh. I want to check the whole process from beginning to end. For that I used strace.
Os name is CentOS. I am working on single machine, server and client are on same machine.
My ...
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0answers
104 views
Why system call hooking produces different result everytime in Linux/Android 2.6.29?
I have implemented system call hooking for Android 2.6.29 kernel through a LKM module. I am tracing down one Android app for system calls. But interestingly, it returns different results every time I ...
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1answer
118 views
How to decode cmd = 3222823425 in ioctl in Linux 2.6.29
I am just confused like how can I break cmd=3222823425 value into different parts to figure out what this command means actually in the Linux kernel. I know, some functions are making ioctl command ...
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1answer
393 views
Calculating total CPU system usage in C
I found this answer on StackOverflow for calculating total CPU usage: http://stackoverflow.com/questions/1420426/calculating-cpu-usage-of-a-process-in-linux/4497769#4497769
But how do I calculate ...
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1answer
111 views
Program stall under user but runs under root
I am running R job under a normal user john and root. Interestingly, the program stalls under john user but runs quickly under root. Using strace, I found that when john runs the R, the process stalls ...
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2answers
546 views
Difference between system calls and library functions
I have been through the answer of this question but do not quite understand the difference between system calls and library functions. Conceptually, what is the difference between the two?
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1answer
62 views
What means the “integer argument” in system call descriptions? [duplicate]
Possible Duplicate:
What do the numbers in a man page mean?
All system calls described in manpages have an associated number such as exec(3). What is the meaning of this number?
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2answers
427 views
exec() and system() system calls
I do understand that while exec() does not return after it executes in Unix ,system() may or may not return depending on the situation.But can anyone explain why exec() system call does not return and ...
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2answers
161 views
How a piped shell programs balance their output/input rates? [duplicate]
Possible Duplicate:
Bash while loop and reading from pipe
I come from web programming background, and find myself interested in one peculiarity of using a local shell. I understand that ...
3
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2answers
982 views
Adding a new System call to Linux 3.2.x with a loadable kernel module [closed]
I want to add a particular new system call in the linux kernel 3.2.x but as a loadable kernel module (as I don't want to recompile the kernel again and again)
I read through many posts on internet ...
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1answer
96 views
Efficient mechanism to determine if open file has been externally modified?
For example, the IDE I'm using at the moment (Aptana Studio) notifies me as soon as a file's contents it has open have been changed by some external program.
I can imagine having a periodic loop run ...
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adding system calls to kernel without recompiling during implementation
Could anyone tell me if it is possible to add several system calls to the linux kernel (version 2.6.35) and not have to recompile the kernel each time I change one of their implementations (i.e. ...
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2answers
1k views
How to find the header file where a c function is defined?
Is there an easy way to find out which header file a C function declaration is in? cding into /usr/include and running (grep -E 'system.*\(' *.h -R) works with some trial and error, but isn't there an ...
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1answer
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Can you perform system calls from OSX Terminal?
So I get system calls in the context of a C program, but my textbook doesn't really address making system calls in Terminal (on Mac OSX). Can you do these on the command line like with "commands", or ...
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1answer
859 views
getrusage system call: what is “maximum resident set size”
man getrusage 2 says
ru_maxrss (since Linux 2.6.32)
This is the maximum resident set size used (in kilobytes). For RUSAGE_CHILDREN, this is the resident set size of the largest
...
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5answers
13k views
How to find application's path from command line?
For example, I have git installed on my system.
But I don't remember where I installed it, so which command is fit to find this out?
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1answer
267 views
System call invokation methods in new kernel
I read that in the newer kernels system calls are invoked using the INT X80 instruction and also using the sysenter instruction. And also the sysenter instruction gives faster invocation as compared ...
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2answers
359 views
Wrapper program that sets signal handler
I would like to have a wrapper program that runs a given command and sets a signal handler so that it gets run when the command receives a specified signal.
The question is this:
Is there an ...
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1answer
94 views
how to disallow user to change process group
Is it possible to restrict a process from changing it's process group? For example, user nobody seems to be able to call setpgid(0, 0) which sets process group of current process to pid of that ...
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2answers
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System programming: How to gather info?
According to this question, a good way to learn system programming would be to implement the existing tools. I decided to try to rewrite ls and ps.
My question is how would one proceed to get ...
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1answer
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DTrace to trap any chmod applied to certain files
Underneath the Mac OS X directory /audit I have certain files which users can access and chmod to their liking.
I need to audit any chmod done on any files by recording the time, user and file being ...
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4answers
1k views
How to understand pipes
When I just used pipe in bash, I didn't think more about this. But when I read some C code example using system call pipe() together with fork(), I wonder how to understand pipes, including both ...
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3answers
2k views
What is the relationship between system calls, message passing, and interrupts?
I am reading the Wikipedia article for process management. My focus is on Linux. I cannot figure out the relation and differences between system call, message passing and interrupt, in their concepts ...
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1answer
889 views
How long is a TCP local socket address that has been bound unavailable after closing?
On Linux (my live servers are on RHEL 5.5 - the LXR links below are to the kernel version in that), man 7 ip says:
A TCP local socket address that has been bound is unavailable for some time after ...
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1answer
781 views
Linux source, where are sys_umount and sys_mount system calls? [duplicate]
Possible Duplicate:
Understanding the linux kernel source
I am sure that I must be missing something, here. I cannot for the life of me find the source code for these system calls. I can ...
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2answers
660 views
Interruption of system calls when a signal is caught
From reading the man pages on the read() and write() calls it appears that these calls get interrupted by signals regardless of whether they have to block or not.
In particular, assume
a process ...
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2answers
1k views
Difference between slow system calls and fast system calls
What's the difference between slow system calls and fast system calls? I have learned that slow system call can block if the process catches some signals, because the caught signals may wake up the ...
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3answers
287 views
Are all system call error numbers unique?
I'm writing a program for Systems Programming in Unix, and one of the requirements is to process all possible error returns from system calls.
So, rather than having a function tailored to each ...
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4answers
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Mnemonics for Unix functions?
Does anyone have any useful mnemonics for remembering the order of function parameters or the return values of Unix system calls? I am suffering from "memory leaks".
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4answers
1k views
Understand error codes in Linux
I am working on Linux (Kernel Version 2.6.32.28) laptop.
After I inserted/did file io/removed a SD combo card, I got following errors:
mmcblk0: error -123 sending status command
mmcblk0: error ...
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2answers
895 views
What's the purpose of the first argument to select system call?
From man select
int select(int nfds, fd_set *readfds, fd_set *writefds,
fd_set *exceptfds, struct timeval *timeout);
nfds is the highest-numbered file descriptor in any of the three ...
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1answer
971 views
Hung system call
So I'm working with a custom kernel module that I'm writing a python front end for. The kernel module works, and it adds a framebuffer device file to /dev/fb1. I can read and write to it fine. I've ...
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4answers
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What is the difference between a Library call and a System call in Linux?
I would like to know what is the difference between a Library call and a System call in Linux. Any pointers for a good understanding of the concepts behind both will be greatly appreciated.
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3answers
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Why should a child of a vfork or fork call _exit() instead of exit()?
From the man page of vfork():
vfork() differs from fork() in that
the parent is suspended until the
child makes a call to execve(2) or
_exit(2). The child shares all memory with its ...
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1answer
2k views
What's the difference between fork() and vfork()?
I would like to understand in detail the difference between fork() and vfork(). I was not able to digest the man page completely.
I would also like to clarify one of my colleagues comment "In ...
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3answers
2k views
flock(2) versus fcntl(2) over a NFS
The Perl 5.x documentation states that its implementation of flock(..) will use one of the following native calls, starting at 1 and working toward 3 if unavailable:
flock(2)
fcntl(2)
lockf(3)
...
