/* sigactdemo.c
* purpose: shows use of sigaction()
* feature: blocks ^\ while handling ^C
* does not reset ^C handler, so two kill
*/
-sharpinclude <stdio.h>
-sharpinclude <signal.h>
-sharpdefine INPUTLEN 100
main()
{
struct sigaction newhandler; /* new settings */
sigset_t blocked; /* set of blocked sigs */
void inthandler(); /* the handler */
char x[INPUTLEN];
/* load these two members first */
newhandler.sa_handler = inthandler; /* handler function */
newhandler.sa_flags = SA_RESETHAND | SA_RESTART; /* options */
/* then build the list of blocked signals */
sigemptyset(&blocked); /* clear all bits */
sigaddset(&blocked, SIGQUIT); /* add SIGQUIT to list */
newhandler.sa_mask = blocked; /* store blockmask */
if ( sigaction(SIGINT, &newhandler, NULL) == -1 )
perror("sigaction");
else
while( 1 ){
fgets(x, INPUTLEN, stdin);
printf("input: %s", x);
}
}
void inthandler(int s)
{
printf("Called with signal %d\n", s);
sleep(s);
printf("done handling signal %d\n", s);
}Unix/Linux system programming practice tutorial book P205 page example, the above use of the function sigaction, is mainly to demonstrate blocking SIGQUIT (ctrl + when processing SIGINT (ctrl + C), search the lower structure sigcation the function of sa_mask is to block the signal when processing, so use sigaddset and other functions to add SIGQUIT signal, but report an error during execution
[root@centos-linux-7 CH07]-sharp ./sigactdemo
^\()
[root@centos-linux-7 CH07]-sharp gcc -v
specs
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/lto-wrapper
:x86_64-redhat-linux
:../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu --enable-languages=c,cPP,objc,obj-cPP,java,fortran,ada,go,lto --enable-plugin --enable-initfini-array --disable-libgcj --with-isl=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/isl-install --with-cloog=/builddir/build/BUILD/gcc-4.8.5-20150702/obj-x86_64-redhat-linux/cloog-install --enable-gnu-indirect-function --with-tune=generic --with-arch_32=x86-64 --build=x86_64-redhat-linux
:posix
gcc 4.8.5 20150623 (Red Hat 4.8.5-28) (GCC)
[root@centos-linux-7 CH07]-sharp