diff options
Diffstat (limited to 'man2/signal.2')
| -rw-r--r-- | man2/signal.2 | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/man2/signal.2 b/man2/signal.2 index 619babf..77f7b19 100644 --- a/man2/signal.2 +++ b/man2/signal.2 @@ -13,7 +13,7 @@ .\" various sections. .\" 2008-07-11, mtk: rewrote and expanded portability discussion. .\" -.TH signal 2 2023-03-30 "Linux man-pages 6.05.01" +.TH signal 2 2023-10-31 "Linux man-pages 6.7" .SH NAME signal \- ANSI C signal handling .SH LIBRARY @@ -22,9 +22,9 @@ Standard C library .SH SYNOPSIS .nf .B #include <signal.h> -.PP +.P .B typedef void (*sighandler_t)(int); -.PP +.P .BI "sighandler_t signal(int " signum ", sighandler_t " handler ); .fi .SH DESCRIPTION @@ -37,7 +37,7 @@ and has also varied historically across different versions of Linux. .BR sigaction (2) instead. See \fIPortability\fP below. -.PP +.P .BR signal () sets the disposition of the signal .I signum @@ -47,7 +47,7 @@ which is either .BR SIG_IGN , .BR SIG_DFL , or the address of a programmer-defined function (a "signal handler"). -.PP +.P If the signal .I signum is delivered to the process, then one of the following happens: @@ -74,7 +74,7 @@ is called with argument .IR signum . If invocation of the handler caused the signal to be blocked, then the signal is unblocked upon return from the handler. -.PP +.P The signals .B SIGKILL and @@ -113,7 +113,7 @@ is defined. Without use of such a type, the declaration of .BR signal () is the somewhat harder to read: -.PP +.P .in +4n .EX .BI "void ( *" signal "(int " signum ", void (*" handler ")(int)) ) (int);" @@ -131,7 +131,7 @@ The semantics when using to establish a signal handler vary across systems (and POSIX.1 explicitly permits this variation); .B do not use it for this purpose. -.PP +.P POSIX.1 solved the portability mess by specifying .BR sigaction (2), which provides explicit control of the semantics when a @@ -141,7 +141,7 @@ signal handler is invoked; use that interface instead of C11, POSIX.1-2008. .SH HISTORY C89, POSIX.1-2001. -.PP +.P In the original UNIX systems, when a handler that was established using .BR signal () was invoked by the delivery of a signal, @@ -151,20 +151,20 @@ and the system did not block delivery of further instances of the signal. This is equivalent to calling .BR sigaction (2) with the following flags: -.PP +.P .in +4n .EX sa.sa_flags = SA_RESETHAND | SA_NODEFER; .EE .in -.PP +.P System\ V also provides these semantics for .BR signal (). This was bad because the signal might be delivered again before the handler had a chance to reestablish itself. Furthermore, rapid deliveries of the same signal could result in recursive invocations of the handler. -.PP +.P BSD improved on this situation, but unfortunately also changed the semantics of the existing .BR signal () @@ -179,13 +179,13 @@ restarted if interrupted by a signal handler (see The BSD semantics are equivalent to calling .BR sigaction (2) with the following flags: -.PP +.P .in +4n .EX sa.sa_flags = SA_RESTART; .EE .in -.PP +.P The situation on Linux is as follows: .IP \[bu] 3 The kernel's @@ -214,7 +214,7 @@ provides System\ V semantics. .\" System V semantics are also provided if one uses the separate .\" .BR sysv_signal (3) .\" function. -.\" .IP * +.\" .IP \[bu] .\" The .\" .BR signal () .\" function in Linux libc4 and libc5 provide System\ V semantics. @@ -229,7 +229,7 @@ provides System\ V semantics. The effects of .BR signal () in a multithreaded process are unspecified. -.PP +.P According to POSIX, the behavior of a process is undefined after it ignores a .BR SIGFPE , @@ -247,14 +247,14 @@ signal. (Also dividing the most negative integer by \-1 may generate .BR SIGFPE .) Ignoring this signal might lead to an endless loop. -.PP +.P See .BR sigaction (2) for details on what happens when the disposition .B SIGCHLD is set to .BR SIG_IGN . -.PP +.P See .BR signal\-safety (7) for a list of the async-signal-safe functions that can be |