Linux System Calls Details

Linux System Calls Details

No	Function Name	Description	Source
1	exit	terminate the current process	kernel/exit.c
2	fork	create a child process	arch/i386/kernel/process.c
3	read	read from a file descriptor	fs/read_write.c
4	write	write to a file descriptor	fs/read_write.c
5	open	open a file or device	fs/open.c
6	close	close a file descriptor	fs/open.c
7	waitpid	wait for process termination	kernel/exit.c
8	creat	create a file or device	fs/open.c
9	link	make a new name for a file	fs/namei.c
10	unlink	delete a name and possibly the file it refers to	fs/namei.c
11	execve	execute program	arch/i386/kernel/process.c
12	chdir	change working directory	fs/open.c
13	time	get time in seconds	kernel/time.c
14	mknod	create a special or ordinary file	fs/namei.c
15	chmod	change permissions of a file	fs/open.c
16	lchown	change ownership of a file	fs/open.c
18	stat	get file status	fs/stat.c
19	lseek	reposition read/write file offset	fs/read_write.c
20	getpid	get process identification	kernel/sched.c
21	mount	mount filesystems	fs/super.c
22	umount	unmount filesystems	fs/super.c
23	setuid	set real user ID	kernel/sys.c
24	getuid	get real user ID	kernel/sched.c
25	stime	set system time and date	kernel/time.c
26	ptrace	allows a parent process to control the execution of a child process	arch/i386/kernel/ptrace.c
27	alarm	set an alarm clock for delivery of a signal	kernel/sched.c
28	fstat	get file status	fs/stat.c
29	pause	suspend process until signal	arch/i386/kernel/sys_i386.c
30	utime	set file access and modification times	fs/open.c
33	access	check user's permissions for a file	fs/open.c
34	nice	change process priority	kernel/sched.c

36	sync	update the super block	fs/buffer.c
37	kill	send signal to a process	kernel/signal.c
38	rename	change the name or location of a file	fs/namei.c
39	mkdir	create a directory	fs/namei.c
40	rmdir	remove a directory	fs/namei.c
41	dup	duplicate an open file descriptor	fs/fcntl.c
42	pipe	create an interprocess channel	arch/i386/kernel/sys_i386.c
43	times	get process times	kernel/sys.c
45	brk	change the amount of space allocated for the calling process's data segment	mm/mmap.c`
46	setgid	set real group ID	kernel/sys.c
47	getgid	get real group ID	kernel/sched.c
48	sys_signal	ANSI C signal handling	kernel/signal.c
49	geteuid	get effective user ID	kernel/sched.c
50	getegid	get effective group ID	kernel/sched.c
51	acct	enable or disable process accounting	kernel/acct.c
52	umount2	unmount a file system	fs/super.c
54	ioctl	control device	fs/ioctl.c
55	fcntl	file control	fs/fcntl.c
56	mpx	(unimplemented)
57	setpgid	set process group ID	kernel/sys.c
58	ulimit	(unimplemented)
59	olduname	obsolete uname system call	arch/i386/kernel/sys_i386.c
60	umask	set file creation mask	kernel/sys.c
61	chroot	change root directory	fs/open.c
62	ustat	get file system statistics	fs/super.c
63	dup2	duplicate a file descriptor	fs/fcntl.c
64	getppid	get parent process ID	kernel/sched.c
65	getpgrp	get the process group ID	kernel/sys.c
66	setsid	creates a session and sets the process group ID	kernel/sys.c
67	sigaction	POSIX signal handling functions	arch/i386/kernel/signal.c
68	sgetmask	ANSI C signal handling	kernel/signal.c

69	ssetmask	ANSI C signal handling	kernel/signal.c
70	setreuid	set real and effective user IDs	kernel/sys.c
71	setregid	set real and effective group IDs	kernel/sys.c
72	sigsuspend	install a signal mask and suspend caller until signal	arch/i386/kernel/signal.c
73	sigpending	examine signals that are blocked and pending	kernel/signal.c
74	sethostname	set hostname	kernel/sys.c
75	setrlimit	set maximum system resource con sumption	kernel/sys.c
76	getrlimit	get maximum system resource con sumption	kernel/sys.c
77	getrusage	get maximum system resource con sumption	kernel/sys.c
78	gettimeofday	get the date and time	kernel/time.c
79	settimeofday	set the date and time	kernel/time.c
80	getgroups	get list of supplementary group IDs	kernel/sys.c
81	setgroups	set list of supplementary group IDs	kernel/sys.c
82	old_select	sync. I/O multiplexing	arch/i386/kernel/sys_i386.c
83	symlink	make a symbolic link to a file	fs/namei.c
84	lstat	get file status	fs/stat.c
85	readlink	read the contents of a symbolic link	fs/stat.c
86	uselib	select shared library	fs/exec.c
87	swapon	start swapping to file/device	mm/swapfile.c
88	reboot	reboot or enable/disable Ctrl-Alt-Del	kernel/sys.c
89	old_readdir	read directory entry	fs/readdir.c
90	old_mmap	map pages of memory	arch/i386/kernel/sys_i386.c
91	munmap	unmap pages of memory	mm/mmap.c
92	truncate	set a file to a specified length	fs/open.c
93	ftruncate	set a file to a specified length	fs/open.c
94	fchmod	change access permission mode of file	fs/open.c
95	fchown	change owner and group of a file	fs/open.c
96	getpriority	get program scheduling priority	kernel/sys.c
97	setpriority	set program scheduling priority	kernel/sys.c

98	profil	execution time profile
99	statfs	get file system statistics	fs/open.c
100	fstatfs	get file system statistics	fs/open.c
101	ioperm	set port input/output permissions	arch/i386/kernel/ioport.c
102	socketcall	socket system calls	net/socket.c
103	syslog	read and/or clear kernel message ring buffer	kernel/printk.c
104	setitimer	set value of interval timer	kernel/itimer.c
105	getitimer	get value of interval timer	kernel/itimer.c
106	sys_newstat	get file status	fs/stat.c
107	sys_newlstat	get file status	fs/stat.c
108	sys_newfstat	get file status	fs/stat.c
109	olduname	get name and information about current kernel	arch/i386/kernel/sys_i386.c
110	iopl	change I/O privilege level	arch/i386/kernel/ioport.c
111	vhangup	virtually hangup the current tty	fs/open.c
112	idle	make process 0 idle	arch/i386/kernel/process.c
113	vm86old	enter virtual 8086 mode	arch/i386/kernel/vm86.c
114	wait4	wait for process termination, BSD style	kernel/exit.c
115	swapoff	stop swapping to file/device	mm/swapfile.c
116	sysinfo	returns information on overall system statistics	kernel/info.c
117	ipc	System V IPC system calls	arch/i386/kernel/sys_i386.c
118	fsync	synchronize a file's complete in-core state with that on disk	fs/buffer.c
119	sigreturn	return from signal handler and cleanup stack frame	arch/i386/kernel/signal.c
120	clone	create a child process	arch/i386/kernel/process.c
121	setdomain-name	set domain name	kernel/sys.c
122	uname	get name and information about current kernel	kernel/sys.c
123	modify_ldt	get or set ldt	arch/i386/kernel/ldt.c
124	adjtimex	tune kernel clock	kernel/time.c
125	mprotect	set protection of memory mapping	mm/mprotect.c

126	sigprocmask	POSIX signal handling functions	kernel/signal.c
127	create_module	create a loadable module entry	kernel/module.c
128	init_module	initialize a loadable module entry	kernel/module.c
129	delete_module	delete a loadable module entry	kernel/module.c
130	get_kernel_syms	retrieve exported kernel and module symbols	kernel/module.c
31	quotactl	manipulate disk quotas	fs/dquot.c
132	getpgid	get process group ID	kernel/sys.c
133	fchdir	change working directory	fs/open.c
134	bdflush	start, flush, or tune buffer-dirty-flush daemon	fs/buffer.c
135	sysfs	get file system type information	fs/super.c
136	personality	set the process execution domain	kernel/exec_domain.c
137	afs_syscall	(unimplemented)
138	setfsuid	set user identity used for file system checks	kernel/sys.c
139	setfsgid	set group identity used for file system checks	kernel/sys.c
140	sys_llseek	move extended read/write file pointer	fs/read_write.c
141	getdents	read directory entries	fs/readdir.c
142	select	sync. I/O multiplexing	fs/select.c
143	flock	apply or remove an advisory lock on an open file	fs/locks.c
144	msync	synchronize a file with a memory map	mm/filemap.c
145	readv	read data into multiple buffers	fs/read_write.c
146	writev	write data into multiple buffers	fs/read_write.c
147	sys_getsid	get process group ID of session leader	kernel/sys.c
148	fdatasync	synchronize a file's in-core data with that on disk	fs/buffer.c
149	sysctl	read/write system parameters	kernel/sysctl.c
150	mlock	lock pages in memory	mm/mlock.c
151	munlock	unlock pages in memory	mm/mlock.c

152	mlockall	disable paging for calling process	mm/mlock.c
153	munlockall	reenable paging for calling process	mm/mlock.c
154	sched_set-param	set scheduling parameters	kernel/sched.c
155	sched_get-param	get scheduling parameters	kernel/sched.c
156	sched_set-scheduler	set scheduling algorithm parameters	kernel/sched.c
157	sched_get-scheduler	get scheduling algorithm parameters	kernel/sched.c
158	sched_yield	yield the processor	kernel/sched.c
159	sched_get_p-riority_max	get max static priority range	kernel/sched.c
160	sched_get_p-riority_min	get min static priority range	kernel/sched.c
161	sched_rr_get_inter-val	get the SCHED_RR interval for the named process	kernel/sched.c
162	nanosleep	pause execution for a specified time (nano seconds)	kernel/sched.c
163	mremap	re-map a virtual memory address	mm/mremap.c
164	setresuid	set real, effective and saved user or group ID	kernel/sys.c
165	getresuid	get real, effective and saved user or group ID	kernel/sys.c
166	vm86	enter virtual 8086 mode	arch/i386/kernel/vm86.c
167	query_module	query the kernel for various bits pertain ing to modules	kernel/module.c
168	poll	wait for some event on a file descriptor	fs/select.c
169	nfsservctl	syscall interface to kernel nfs daemon	fs/filesystems.c
170	setresgid	set real, effective and saved user or group ID	kernel/sys.c
171	getresgid	get real, effective and saved user or group ID	kernel/sys.c
172	prctl	operations on a process	kernel/sys.c
173	rt_sigreturn		arch/i386/kernel/signal.c
174	rt_sigaction		kernel/signal.c

175	rt_sigprocmask		kernel/signal.c
176	rt_sigpending		kernel/signal.c
177	rt_sigtimedwait		kernel/signal.c
178	rt_sigqueueinfo		kernel/signal.c
179	rt_sigsuspend		arch/i386/kernel/signal.c
180	pread	read from a file descriptor at a given offset	fs/read_write.c
181	sys_pwrite	write to a file descriptor at a given offset	fs/read_write.c
182	chown	change ownership of a file	fs/open.c
183	getcwd	Get current working directory	fs/dcache.c
184	capget	get process capabilities	kernel/capability.c
185	capset	set process capabilities	kernel/capability.c
186	sigaltstack	set/get signal stack context	arch/i386/kernel/signal.c
187	sendfile	transfer data between file descriptors	mm/filemap.c
188	getpmsg	(unimplemented)
189	putpmsg	(unimplemented)
190	vfork	create a child process and block parent	arch/i386/kernel/process.c

Control Keys

Control keys-those that you type by holding down the CONTROL (or CTRL) key and hitting another key-are another
type of special character. These normally don't print anything on your screen, but the operating system interprets a few
of them as special commands. You already know one of them: RETURN is actually the same as [CTRL-M] (try it and
see). You have probably also used the BACKSPACE or DEL key to erase typos on your command line.
Perhaps the most difficult thing about control keys is that they can differ from system to system. The usual arrangement
is shown in Table which lists the control keys that all major modern versions of UNIX support. Note that [CTRL-\] and [CTRL-|] (control-backslash and control-pipe) are the same character notated two different ways; the same is true of DEL and [CTRL-?].
You can use the stty command to find out what your settings are and change them if you wish;
If the version of UNIX on your system is one of those that derive from BSD (such as SunOS and Ultrix), type stty --all or stty -a to see your control-key settings; you will see something like this:
erase kill werase rprnt flush lnext susp intr quit stop eof
^? ^U ^W ^R ^O ^V ^Z/^Y ^C ^| ^S/^Q ^D

Control Key stty Name Function Description
CTRL-C intr Stop current command
CTRL-D eof End of input
[CTRL-\] or [CTRL-|] quit Stop current command, if [CTRL-C] doesn't work
CTRL-S stop Halt output to screen
CTRL-Q Restart output to screen
DEL or [CTRL-?] erase Erase last character
CTRL-U kill Erase entire command line
CTRL-Z susp Suspend current command

The ^X notation stands for CTRL-X. If your UNIX version derives from System III or System V (this includes AIX,
HP/UX, SCO, and Xenix), type stty -a; the resulting output will include this information:
intr = ^c; quit = ^|; erase = DEL; kill = ^u; eof = ^d; eol = ^`; swtch = ^`
susp = ^z; dsusp ;

The control key you will probably use most often is [CTRL-C], sometimes called the interrupt key. This stops-or tries to stop-the command that is currently running. You will want to use this when you enter a command and find that it's taking too long, you gave it the wrong arguments by mistake, you change your mind about wanting to run it, or whatever.

Sometimes [CTRL-C] doesn't work; in that case, if you really want to stop a job, try [CTRL-\]. But don't just type CTRL-\; always try [CTRL-C] first! Chapter 8 explains why in detail. For now, suffice it to say that [CTRL-C] gives the running job more of a chance to clean up before exiting, so that files and other resources are not left in funny states.

We've already seen an example of [CTRL-D]. When you are running a command that accepts standard input from your keyboard, [CTRL-D] tells the process that your input is finished-as if the process were reading a file and it reached the end of the file. mail is a utility in which this happens often. When you are typing in a message, you end by typing [CTRL-D]. This tells mail that your message is complete and ready to be sent. Most utilities that accept standard input
understand [CTRL-D] as the end-of-input character, though many such programs accept commands like q, quit, exit, etc. The shell itself understands [CTRL-D] as the end-of-input character: as we saw earlier in this chapter, you can normally end a login session by typing [CTRL-D] at the shell prompt. You are just telling the shell that its command input is finished.

CTRL-S and [CTRL-Q] are called flow-control characters. They represent an antiquated way of stopping and restarting the flow of output from one device to another (e.g., from the computer to your terminal) that was useful when the speed of such output was low. They are rather obsolete in these days of high-speed local networks and dialup lines. In fact, under the latter conditions, CTRL-S and [CTRL-Q] are basically a nuisance. The only thing you really need to know
about them is that if your screen output becomes "stuck," then you may have hit [CTRL-S] by accident. Type [CTRL-Q] to restart the output; any keys you may have hit in between will then take effect.

The final group of control characters gives you rudimentary ways to edit your command line. DEL acts as a backspace key (in fact, some systems use the actual BACKSPACE or [CTRL-H] key as "erase" instead of DEL); [CTRL-U] erases the entire line and lets you start over. Again, these are outmoded. [13] Instead of using these, go to the next chapter and read about Korn shell's editing modes, which are among its most exciting features.
[13] Why are so many outmoded control keys still in use? They have nothing to do with the shell per se; instead, they are recognized by the tty driver, an old and hoary part of the operating system's lower depths that controls input and output to/from your terminal.

env command

Environment Variable	Description
BASH	Path of the BASH executable file
BASH_ENV	Path of the BASH environment file, which specifies BASH options
BASH_VERSION	Version of BASH
COLUMNS	Width, in characters, of console window
EUID	Effective user ID
HISTFILE	Path of the BASH command history file
HISTFILESIZE	Maximum number of lines recorded in history file
HISTSIZE	Maximum number of commands recorded in history file
HOME	Path of user’s home directory
HOSTNAME	Name of the host
IFS	Field separator (white space) characters
LINES	Length, in lines, of console window
LOGNAME	User’s log in name
LS_COLORS	Options for ls command
OSTYPE	Operating system name (”Linux”)
PATH	Program path
PPID	Process ID of the shell’s parent process
PS1	Command prompt string
PS2	Continuation prompt string
PS4	Execution trace string
PWD	Current working directory
SHELL	Path of the shell executable
SHLVL	Number of nested shell invocations
TERM	Terminal type
UID	User ID
USER	User name

Ref:http://www.linux-mag.com/id/803
http://linux.about.com/od/ttl_howto/a/hwtttl16t06.htm