C.1.2 Environment (J.3.2) (Sun Studio 12: C User's Guide)

Sun Studio 12: C User's Guide

C.1.2 Environment (J.3.2)

The mapping between physical source file multi-byte characters and the source character set in translation phase 1 (5.1.1.2).

There are eight bits in a character for the ASCII portion; locale-specific multiples of eight bits for locale-specific extended portion.
The name and type of the function called at program startup in a freestanding environment (5.1.2.1).

The implementation is hosted environment.
The effect of program termination in a freestanding environment (5.1.2.1).

The implementation is in a hosted environment.
An alternative manner in which the main function may be defined (5.1.2.2.1).

There is no alternative way to define main other than that defined in the standard.
The values given to the strings pointed to by the argv argument to main (5.1.2.2.1).

argv is an array of pointers to the command-line arguments, where argv[0] represents the program name if it is available.
What constitutes an interactive device (5.1.2.3).

An interactive device is one for which the system library call isatty() returns a nonzero value
The set of signals, their semantics, and their default handling (7.14).

The following table shows the semantics for each signal as recognized by the signal function:

Table C–1 Semantics of signal Function Signals


Signal Number	Default Event	Semantics of Signal
`SIGHUP 1`	Exit	hangup
`SIGINT 2`	Exit	interrupt (rubout)
`SIGQUIT 3`	Core	quit (ASCII FS)
`SIGILL 4`	Core	illegal instruction (not reset when caught)
`SIGTRAP 5`	Core	trace trap (not reset when caught)
`SIGIOT 6`	Core	IOT instruction
`SIGABRT 6`	Core	Used by abort
`SIGEMT 7`	Core	EMT instruction
`SIGFPE 8`	Core	floating point exception
`SIGKILL 9`	Exit	kill (cannot be caught or ignored)
`SIGBUS 10`	Core	bus error
`SIGSEGV 11`	Core	segmentation violation
`SIGSYS 12`	Core	bad argument to system call
`SIGPIPE 13`	Exit	write on a pipe with no one to read it
`SIGALRM 14`	Exit	alarm clock
`SIGTERM 15`	Exit	software termination signal from kill
`SIGUSR1 16`	Exit	user defined signal 1
`SIGUSR2 17`	Exit	user defined signal 2
`SIGCLD 18`	Ignore	child status change
`SIGCHLD 18`	Ignore	child status change alias (POSIX)
`SIGPWR 19`	Ignore	power-fail restart
`SIGWINCH 20`	Ignore	window size change
`SIGURG 21`	Ignore	urgent socket condition
`SIGPOLL 22`	Exit	pollable event occurred
`SIGIO 22`	Sigpoll	socket I/O possible
`SIGSTOP 23`	Stop	stop (cannot be caught or ignored)
`SIGTSTP 24`	Stop	user stop requested from tty
`SIGCONT 25`	Ignore	stopped process has been continued
`SIGTTIN 26`	Stop	background tty read attempted
`SIGTTOU 27`	Stop	background tty write attempted
`SIGVTALRM 28`	Exit	virtual timer expired
`SIGPROF 29`	Exit	profiling timer expired
`SIGXCPU 30`	Core	exceeded cpu limit
`SIGXFSZ 31`	Core	exceeded file size limit
`SIGWAITING 32`	Ignore	reserved signal no longer used by threading code
`SIGLWP 33`	Ignore	reserved signal no longer used by threading code
`SIGFREEZE 34`	Ignore	Checkpoint suspend
`SIGTHAW 35`	Ignore	Checkpoint resume
`SIGCANCEL 36`	Ignore	Cancellation signal used by threads library
`SIGLOST 37`	Ignore	resource lost (record-lock lost)
`SIGXRES 38`	Ignore	Resource control exceeded (see setrctl(2))
`SIGJVM1 39`	Ignore	Reserved for Java Virtual Machine 1
`SIGJVM2 40`	Ignore	Reserved for Java Virtual Machine 2

Signal values other than SIGFPE, SIGILL, and SIGSEGV that correspond to a computational exception (7.14.1.1).

SIGILL, SIGFPE, SIGSEGV, SIGTRAP, SIGBUS, and SIGEMT, see Table C–1.
Signals for which the equivalent of signal(sig, SIG_IGN); is executed at program startup (7.14.1.1).A

SIGILL, SIGFPE, SIGSEGV, SIGTRAP, SIGBUS, and SIGEMT, see Table C–1.
The set of environment names and the method for altering the environment list used by the getenv function (7.20.4.5).

The environment names are listed in the man page environ(5).
The manner of execution of the string by the system function (7.20.4.6).

From the system(3C) man page:

The system() function causes string to be given to the shell as input, as if string had been typed as a command at a terminal. The invoker waits until the shell has completed, then returns the exit status of the shell in the format specified by waitpid(2).

If string is a null pointer, system() checks if the shell exists and is executable. If the shell is available, system() returns a non-zero value; otherwise, it returns 0.