Linux System Call Quick Reference printable pdf download

LINUX System Call Quick Reference

create a file or device ("man 2 open" for

fs/open.c

creat

information)

Jialong He

make a new name for a file

fs/namei.c

link

delete a name and possibly the file it refers to

fs/namei.c

unlink

execute program

arch/i386/kernel/process.c

execve

Introduction

change working directory

fs/open.c

chdir

System call is the services provided by Linux kernel. In C programming, it often uses functions defined in libc

get time in seconds

kernel/time.c

time

which provides a wrapper for many system calls. Manual page section 2 provides more information about

create a special or ordinary file

fs/namei.c

mknod

system calls. To get an overview, use “man 2 intro” in a command shell.

change permissions of a file

fs/open.c

chmod

It is also possible to invoke syscall() function directly. Each system call has a function number defined in

change ownership of a file

fs/open.c

lchown

<syscall.h> or <unistd.h>. Internally, system call is invokded by software interrupt 0x80 to transfer control to

the kernel. System call table is defined in Linux kernel source file “arch/i386/kernel/entry.S ”.

get file status

fs/stat.c

stat

System Call Example

reposition read/write file offset

fs/read_write.c

lseek

get process identification

kernel/sched.c

getpid

#include <syscall.h>

#include <unistd.h>

mount filesystems

fs/super.c

mount

#include <stdio.h>

unmount filesystems

fs/super.c

umount

#include <sys/types.h>

set real user ID

kernel/sys.c

setuid

int main(void) {

get real user ID

kernel/sched.c

getuid

long ID1, ID2;

set system time and date

kernel/time.c

stime

/*-----------------------------*/

allows a parent process to control the execution of

arch/i386/kernel/ptrace.c

/* direct system call

ptrace

a child process

/* SYS_getpid (func no. is 20) */

/*-----------------------------*/

set an alarm clock for delivery of a signal

kernel/sched.c

alarm

ID1 = syscall(SYS_getpid);

get file status

fs/stat.c

fstat

printf ("syscall(SYS_getpid)=%ld\n", ID1);

suspend process until signal

arch/i386/kernel/sys_i386.c

pause

/*-----------------------------*/

set file access and modification times

fs/open.c

utime

/* "libc" wrapped system call

/* SYS_getpid (Func No. is 20) */

check user's permissions for a file

fs/open.c

access

/*-----------------------------*/

change process priority

kernel/sched.c

nice

ID2 = getpid();

printf ("getpid()=%ld\n", ID2);

update the super block

fs/buffer.c

sync

send signal to a process

kernel/signal.c

kill

return(0);

}

change the name or location of a file

fs/namei.c

rename

create a directory

fs/namei.c

mkdir

System Call Quick Reference

remove a directory

fs/namei.c

rmdir

No Func Name Description

Source

duplicate an open file descriptor

fs/fcntl.c

dup

create an interprocess channel

arch/i386/kernel/sys_i386.c

pipe

terminate the current process

kernel/exit.c

exit

get process times

kernel/sys.c

times

create a child process

arch/i386/kernel/process.c

fork

change the amount of space allocated for the

mm/mmap.c

brk

read from a file descriptor

fs/read_write.c

read

calling process's data segment

write to a file descriptor

fs/read_write.c

write

set real group ID

kernel/sys.c

setgid

open a file or device

fs/open.c

open

get real group ID

kernel/sched.c

getgid

close a file descriptor

fs/open.c

ANSI C signal handling

kernel/signal.c

sys_signal

wait for process termination

kernel/exit.c

waitpid

get effective user ID

kernel/sched.c

geteuid

get effective group ID

kernel/sched.c

getegid

Linux System Call Quick Reference

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