<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> <!--Converted with LaTeX2HTML 96.1-c (Feb 29, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds --> <HTML> <HEAD> <TITLE>10.2.1 Signals under SVR4, BSD, and POSIX.1</TITLE> <META NAME="description" CONTENT="10.2.1 Signals under SVR4, BSD, and POSIX.1"> <META NAME="keywords" CONTENT="lpg"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <LINK REL=STYLESHEET HREF="lpg.css"> </HEAD> <BODY LANG="EN"> <A NAME="tex2html2079" HREF="node140.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="/icons//next_motif.gif"></A> <A NAME="tex2html2077" HREF="node138.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="/icons//up_motif.gif"></A> <A NAME="tex2html2071" HREF="node138.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="/icons//previous_motif.gif"></A> <A NAME="tex2html2081" HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="/icons//contents_motif.gif"></A> <BR> <B> Next:</B> <A NAME="tex2html2080" HREF="node140.html">10.2.2 Linux signal options</A> <B>Up:</B> <A NAME="tex2html2078" HREF="node138.html">10.2 Signal handling</A> <B> Previous:</B> <A NAME="tex2html2072" HREF="node138.html">10.2 Signal handling</A> <BR> <P> <H2><A NAME="SECTION001121000000000000000">10.2.1 Signals under SVR4, BSD, and POSIX.1</A></H2> <P> The SVR4 implementation of signals incorporates the functions <EM>signal</EM>, <EM>sigset</EM>, <EM>sighold</EM>, <EM>sigrelse</EM>, <EM>sigignore</EM>, and <EM>sigpause</EM>. The <EM>signal</EM> function under SVR4 is identical to the classic UNIX V7 signals, providing only unreliable signals. The other functions do provide signals with automatic reinstallation of the signal handler, but no system call restarting is supported. <P> Under BSD, the functions <EM>signal</EM>, <EM>sigvec</EM>, <EM>sigblock</EM>, <EM>sigsetmask</EM>, and <EM>sigpause</EM> are supported. All of the functions provide reliable signals with system call restarting by default, but that behavior can be disabled if the programmer wishes. <P> Under POSIX.1, <EM>sigaction</EM>, <EM>sigprocmask</EM>, <EM>sigpending</EM>, and <EM>sigsuspend</EM> are provided. Note that there is no <EM>signal</EM> function, and according to POSIX.1 it is depreciated. These functions provide reliable signals, but system call restart behavior is not defined by POSIX. If <EM>sigaction</EM> is used under SVR4 and BSD, system call restarting is disabled by default, but it can be turned on if the signal flag <TT>SA_RESTART</TT> is specified. <P> Therefore, the ``best'' way to use signals in a program is to use <EM>sigaction</EM>, which allows you to explicitly specify the behavior of signal handlers. However, <EM>signal</EM> is still used in many applications, and as we can see above <EM>signal</EM> provides different semantics under SVR4 and BSD. <P> <BR> <HR> <P><ADDRESS> <I>Converted on: <BR> Fri Mar 29 14:43:04 EST 1996</I> </ADDRESS> </BODY> </HTML>
