SYSCALL(1) General Commands Manual SYSCALL(1)NAME
syscall - test a system call
SYNOPSIS
syscall [ -o ] entry [ arg ... ]
DESCRIPTION
Syscall invokes the system call entry with the given arguments. It prints the return value and the error string, if there was an error.
An argument is either an integer constant as in C (its value is passed), a string (its address is passed), or the literal buf (a pointer to
a 1 Kbyte buffer is passed). If -o is given, the contents of the 1 Kbyte buffer are printed as a zero-terminated string after the system
call is done.
EXAMPLES
Write a string to standard output
syscall write 1 hello 5
Print the name of the file connected to standard input
syscall -o fstat 0 buf
SOURCE
/sys/src/cmd/syscall
SEE ALSO
Section 2 of this manual.
DIAGNOSTICS
If entry is not a system call name, the exit status is If the system call succeeds, the exit status is null; otherwise the exit status is
the string that errstr(2) returns.
SYSCALL(1)
Check Out this Related Man Page
SYSCALL(2) BSD System Calls Manual SYSCALL(2)NAME
syscall, __syscall -- indirect system call
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/syscall.h>
#include <unistd.h>
int
syscall(int number, ...);
quad_t
__syscall(quad_t number, ...);
DESCRIPTION
syscall() performs the system call whose assembly language interface has the specified number with the specified arguments. Symbolic con-
stants for system calls can be found in the header file <sys/syscall.h>. The __syscall form should be used when one or more of the parame-
ters is a 64-bit argument to ensure that argument alignment is correct.
This system call is useful for testing new system calls that do not have entries in the C library. It should not be used in normal applica-
tions.
RETURN VALUES
The return values are defined by the system call being invoked. In general, a 0 return value indicates success. A -1 return value indicates
an error, and an error code is stored in errno.
HISTORY
The syscall() function call appeared in 4.0BSD.
BUGS
There is no way to simulate system calls that have multiple return values such as pipe(2).
Since architectures return 32 bit and 64 bit results in different registers, it may be impossible to portably convert the result of
__syscall() to a 32bit value. For instance sparc returns 32 bit values in %o0 and 64 bit values in %o0:%o1 (with %o0 containing the most
significant part) so a 32 bit right shift of the result is needed to get a correct 32 bit result.
Many architectures mask off the unwanted high bits of the syscall number, rather than returning an error.
Due to ABI implementation differences in passing struct or union type arguments to system calls between different processors, all system
calls pass instead pointers to such structs or unions, even when the documentation of the system call mentions otherwise. The conversion
between passing structs and unions is handled normally via userland stubs. The correct arguments for the kernel entry points for each system
call can be found in the header file <sys/syscallargs.h>
BSD August 7, 2009 BSD
I have a question regarding the recv syscall.
Suppose I have a client/server and the following exchange of message took place:
Client --> Server using multiple send syscalls one after another immediately:
send "Packet1"
send "Packet2"
send "Packet3"
Server receives in the... (2 Replies)
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i just started started learning system programming and want to pursue a career in the sys prog area.
below is the program that use a fork() call.
i read in one of the tutorials that parent process and child process uses different address spaces and runs concurrently.
that meas each... (2 Replies)
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I am using ptrace to keep track of clone syscalls in a program. However, I found that the traced syscall cant be paired. for example, there are some syscalls that have entry, but without exit showing up in the traced sequences. So, is there anyway to distinguish the entry and exit of a... (0 Replies)
This is the gdb backtrace.
^C
Program received signal SIGINT, Interrupt.
0xffffe424 in __kernel_vsyscall ()
(gdb) bt
#0 0xffffe424 in __kernel_vsyscall ()
#1 0xb7e56a70 in __nanosleep_nocancel () from /lib/libc.so.6
#2 0xb7e568bb in __sleep (seconds=0) at sleep.c:138
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This was the output:
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I saw somewhere that describe read() as a primitive. But when I lean signals, it says the read() may be interrupted by a signal.
My Question:
1, What is the diffence between primitive and reentrant?
2, Is read() a primitive or reentrant?
3, Are all system calls primitive or reentrant? (2 Replies)
We have just enabled core dump on our RHEL5.7 OS. the java process is terminating very often so we enable core dump to analysis the issue and find below in core dump file.
Core was generated by `/usr/java/jdk1.6.0_06//bin/java -server -Xms1536m -Xmx1536m -Xmn576m -XX:+Aggre'.
Program... (0 Replies)
Hello Experts,
If a Solaris process is calling some syscall, and right now execution is inside syscall doing only CPU work, for example the inside simplest times syscall,
-> app_func
=> times
<< we are here now, we have entered in the times, but not exited yet
<= times
<- app_func... (9 Replies)
Hi,
I wanna add my own system call to Fedora 18 kernel 3.8.2.
From kernel 3.3 I heard there is a new system to add system calls.
So where i can find a guides ?
I wanna print this text: "Hello world!" in terminal, not dmesg. (4 Replies)
Hello to all
I want download a file in osx intel 64 with NASM , I want to use socket syscall
This is part of my code
section .data
command db "GET /test/2.gif HTTP/1.1\r\nHost: 10.1.1.187\r\n\r\n", 0
; url db "http://172.16.207.153/test/2.gif", 0
global main... (1 Reply)
When I use this command:
purify gcc -g hello_world.c
to instrument a C program with Purify, I get this error :
Purify engine:Error: The /usr/lib/syscalls.imp file either does not exist or has incorrect permissions.You may need to install bos.adt.syscalls
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Please use CODE tags when displaying sample input, output, and code segments. (13 Replies)